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157-554: An AR-15–style rifle is a lightweight semi-automatic rifle based on or similar to the Colt AR-15 design. The Colt model removed the selective fire feature of its predecessor, the original ArmaLite AR-15 , which is a scaled-down derivative of the AR-10 design (by Eugene Stoner ). It is closely related to the military M16 rifle . ArmaLite sold the patent and trademarks for both to Colt's Manufacturing Company in 1959 after

314-448: A Canadian -born firearms designer, was tasked with designing a basic gas-actuated self-loading infantry rifle and carbine that would eject the spent cartridge and reload a new round using a gas-operated system. Designing a rifle that was practical in terms of effectiveness, reliability, and production was difficult, and it took fifteen years to perfect the M1 prototype model to meet all

471-540: A Monte Carlo stock instead of a pistol grip, which may allow it to be legally possessed in jurisdictions with assault weapon restrictions in place. It also uses a proprietary bolt carrier due to the angled buffer tube, and a proprietary fire control group that moves the trigger rearward. A few manufactures offer bolt action or pump action AR-15–style rifles incapable of semi-automatic fire. These are most commonly marketed in jurisdictions where ownership of semi-automatic centerfire rifles are heavily restricted, such as in

628-506: A Winchester rifle . Another of the first designs of a recoil-operated semi-automatic rifle is attributed to Ferdinand Mannlicher , who unveiled his design in 1885 based on work begun in 1883. Other non-gas operated semi-automatic models were the Model 85 and Mannlicher Models 91, 93 and 95 rifles. The designs never proceeded past the conceptual/prototype stage due to issues inherent to the black powder used in their cartridges (based around

785-577: A lower house based on population; and the Senate , an upper house based on equal representation for each state. Federalism provides substantial autonomy to the 50 states, while the country's political culture promotes liberty , equality , individualism , personal autonomy , and limited government . One of the world's most developed countries , the United States has had the largest nominal GDP since about 1890 and accounted for over 15% of

942-580: A " Special Relationship " with the United Kingdom and strong ties with Canada , Australia , New Zealand , the Philippines , Japan , South Korea , Israel , and several European Union countries ( France , Italy , Germany , Spain , and Poland ). The U.S. works closely with its NATO allies on military and national security issues, and with countries in the Americas through

1099-434: A category which includes AR-15–style rifles. According to a 2013 analysis by Mayors Against Illegal Guns , 14 out of 93 mass shootings involved high-capacity magazines or assault weapons . Nevertheless, AR-15–style rifles have played a prominent role in many high-profile mass shootings in the U.S. and have come to be widely characterized as the weapon of choice for perpetrators of these crimes. AR-15s or similar rifles were

1256-668: A conventional direct impingement , operating system), and was patented under U.S. patent 2,951,424 . A lighter weight selective fire variant of the AR-10 was designed in 1958 for military use and designated the ArmaLite model 15, or AR-15. Due to financial problems and limitations in terms of manpower and production capacity, ArmaLite sold the AR-15 and AR-10 designs and trademarks to Colt in 1959. In 1964, Colt began selling its own version with an improved semi-automatic design known as

1413-542: A coordinated, continent-wide military effort. Finally, deteriorating relations between the British military establishment and the colonists, relations that were already less than positive, set the stage for further distrust and dislike of British troops. Following their victory in the French and Indian War, Britain began to assert greater control over local colonial affairs, resulting in colonial political resistance ; one of

1570-534: A decentralized government that operated until 1789. After the British surrender at the siege of Yorktown in 1781 American sovereignty was internationally recognized by the Treaty of Paris (1783), through which the U.S. gained territory stretching west to the Mississippi River, north to present-day Canada, and south to Spanish Florida . The Northwest Ordinance (1787) established the precedent by which

1727-407: A few prominent industrialists , largely by their formation of trusts and monopolies to prevent competition. Tycoons led the nation's expansion in the railroad , petroleum , and steel industries. The United States emerged as a pioneer of the automotive industry . These changes were accompanied by significant increases in economic inequality , slum conditions , and social unrest , creating

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1884-488: A firearm with a barrel length of less than 16 inches (41 cm) and an overall length (OAL) of less than 26 inches (66 cm), that was not made from a rifle (including through modification), is not considered to be a short-barreled rifle . As the inclusion of a shoulder stock constitutes "intent to fire from the shoulder" and thus reclassifies the firearm as a rifle, many gun manufacturers offer AR-15–style "pistol" versions that are manufactured to be sold stockless or with

2041-638: A founding member of the World Bank , Organization of American States , NATO , and the United Nations , as well as a permanent member of the UN Security Council . The first documented use of the phrase "United States of America" is a letter from January 2, 1776. Stephen Moylan , a Continental Army aide to General George Washington , wrote to Joseph Reed , Washington's aide-de-camp , seeking to go "with full and ample powers from

2198-579: A gas-operated conversion system from an American inventor named Henry Pitcher. Other designs also developed, such as the Cei-Rigotti in 1900. In 1906, Remington Arms introduced the " Remington Auto-loading Repeating Rifle ". Remington advertised this rifle, renamed the "Model 8" in 1911, as a sporting rifle. It was sold in Europe by FN Herstal as the "FN Browning 1900". The rifle is a locked breech, long recoil action designed by John Browning , and

2355-666: A large volume of fire was deemed more important – during World War II , American ground forces fired approximately 25,000 rounds for each enemy killed. In the Korean War , this number raised to 50,000, and in the Vietnam War it became 200,000 rounds per enemy. The first fully automatic rifle to see widespread usage was the German StG 44 , which was reportedly well-liked by troops, as the 30-round selective fire rifle gave them much more flexibility than their service rifle ,

2512-459: A law to ban semi-automatic center-fire rifles, magazines holding more than 10 rounds, and parts that can be used to assemble prohibited firearms . After the 2020 Nova Scotia attacks , the deadliest rampage by a single person in Canadian history, Canada banned a class of firearms, including the AR-15. Semi-automatic rifle In 1883, Hiram Maxim patented a recoil-operated conversion of

2669-445: A metal rod pushes against the bolt carrier, driven by a piston located just behind the barrel gas port. This piston design keeps the rifle cleaner by not exhausting in to the receiver. Other AR-15–style rifles feature redesigned gas systems so the rifle is "over-the-beach capable", allowing it fire safely as quickly as possible after being submerged in water. The original design features a free-floating firing pin . To theoretically reduce

2826-598: A period of heightened, overt racism following Reconstruction, a time often called the nadir of American race relations . A series of Supreme Court decisions, including Plessy v. Ferguson , emptied the Fourteenth and Fifteenth Amendments of their force, allowing Jim Crow laws in the South to remain unchecked, sundown towns in the Midwest, and segregation in communities across the country , which would be reinforced by

2983-529: A pistol grip like the military versions, but as the pistol grip is generally removable, grips and stocks that comply with various restrictions are available. While AR-15–style rifles are banned in New York City , the FightLite SCR has been explicitly allowed, even though it accepts standard AR-15 upper receivers. The SCR lower receiver differs from the standard AR-15 lower receiver in that it uses

3140-488: A prominent leader in the early 1960s. The Great Society plan of President Lyndon Johnson 's administration resulted in groundbreaking and broad-reaching laws, policies and a constitutional amendment to counteract some of the worst effects of lingering institutional racism . The counterculture movement in the U.S. brought significant social changes, including the liberalization of attitudes toward recreational drug use and sexuality . It also encouraged open defiance of

3297-487: A self-loading mechanism makes self-loading rifles more expensive to manufacture and heavier than manually loaded rifles. The semi-automatic M1 Garand weighs about 410 grams (0.9 lb) more (around seven percent) than the manually loaded M1903 Springfield it replaced. American development of a self-loading infantry rifle began with the .276 Pedersen cartridge in recognition of the difficulties of producing reliable self-loading mechanisms for more powerful cartridges. Although

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3454-526: A sense of manifest destiny . The Missouri Compromise attempted to balance the desire of northern states to prevent the expansion of slavery into new territories with that of southern states to extend it, admitting Missouri as a slave state and Maine as a free state. It further prohibited slavery in all other lands of the Louisiana Purchase north of the 36°30′ parallel . As Americans expanded further into land inhabited by Native Americans,

3611-614: A sense of American identity as well. Men who otherwise never left their own colony now traveled across the continent to fight alongside men from decidedly different backgrounds but who were no less "American". British officers trained American officers for battle, most notably George Washington ; these officers would lend their skills and expertise to the colonists' cause during the American Revolutionary War to come. In addition, colonial legislatures and officials found it necessary to cooperate intensively in pursuit of

3768-568: A single target multiple times rapidly or multiple targets rapidly, greatly increases the effectiveness of a firearm in most applications. Reloading is a downtime from shooting and is a time of vulnerability in hostile applications. Semi-automatic rifles require less frequent reloading than single shot rifles. Semi-automatic rifles can typically more than double the hits at close range and increase hits by about 50% at longer distances compared to manually loaded rifles. The added weight of springs and fittings in self-loading mechanisms, along with some of

3925-410: A stabilizing pistol brace. Once a firearm has been configured as a rifle, whether through modification or originally manufactured that way, it can't be converted back into a pistol. The lower receiver alone is legally defined as a firearm under United States federal law. However, the legality of this definition has been disputed in conflicting court rulings as to whether the AR-15 lower receiver matches

4082-632: A status solidified after its involvement in World War I . After Japan 's attack on Pearl Harbor in December 1941, the U.S. entered World War II . Its aftermath left the U.S. and the Soviet Union as the world's two superpowers and led to the Cold War , during which both countries struggled for ideological dominance and international influence . Following the Soviet Union's collapse and

4239-405: A target and providing a large variety of customization ranging from scopes and muzzle devices, to different calibers. Semi-automatic fire greatly assists in maintaining one's sight picture, which is especially important when follow-up shots are required. Due to their demand, the manufacturers of semi-automatic firearms have greatly increased the effective firing distance of their products compared to

4396-401: A year). Juvenile correctional facilities are operated by local or state governments and serve as longer-term placements for any minor adjudicated as delinquent and ordered by a judge to be confined. As of January 2023, the United States has the sixth-highest per capita incarceration rate in the world—531 people per 100,000 inhabitants—and the largest prison and jail population in

4553-413: Is attached to the upper receiver by two removable pins. Disassembly for cleaning or repair of malfunctions requires disengaging these pins from the upper receiver. Releasing the rear take-down pin allows the receiver to be opened by rotation around the forward pivot pin as a hinge . The upper receiver contains the bolt carrier assembly and is attached to the barrel assembly. Sights may be attached to

4710-591: Is believed to be the first widespread culture in the Americas. Over time, indigenous North American cultures grew increasingly sophisticated, and some, such as the Mississippian culture , developed agriculture , architecture , and complex societies . In the post-archaic period , the Mississippian cultures were located in the midwestern , eastern , and southern regions, and the Algonquian in

4867-498: Is known as the presidential system , in contrast to the parliamentary system , where the executive is part of the legislative body. Many countries around the world imitated this aspect of the 1789 Constitution of the United States , especially in the Americas. The Constitution is silent on political parties. However, they developed independently in the 18th century with the Federalist and Anti-Federalist parties. Since then,

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5024-438: Is now the United States experienced conflicts with Native Americans, they also engaged in trade, exchanging European tools for food and animal pelts. Relations ranged from close cooperation to warfare and massacres. The colonial authorities often pursued policies that forced Native Americans to adopt European lifestyles, including conversion to Christianity. Along the eastern seaboard, settlers trafficked African slaves through

5181-552: Is the federal agency charged with addressing most environmental-related issues . The idea of wilderness has shaped the management of public lands since 1964, with the Wilderness Act . The Endangered Species Act of 1973 provides a way to protect threatened and endangered species and their habitats. The United States Fish and Wildlife Service implements and enforces the Act. In 2024, the U.S. ranked 34th among 180 countries in

5338-417: Is used by both military and sporting AR-15–style rifles. As civilian ownership of AR-15–style rifles became sufficient to create a market for improvements, numerous manufacturers began producing aftermarket parts—including parts with features not found on basic AR-15 rifles, and individuals with basic mechanical aptitude can often substitute these pieces for original equipment without needing a gunsmith. Due to

5495-466: The .50 BMG Barrett M82 . Semi-automatic weapons use gas , blow-forward , blowback or recoil energy to eject spent cartridges after the round has moved down the barrel , to chamber a new cartridge from the weapon's magazine , and to reset the action . This enables another round to be fired once the trigger is depressed again. Semi-automatic rifles can be fed by an en-bloc clip , external magazine , or stripper clip . The self-loading design

5652-603: The Allies of World War I , helping to turn the tide against the Central Powers . In 1920, a constitutional amendment granted nationwide women's suffrage . During the 1920s and '30s, radio for mass communication and the invention of early television transformed communications nationwide. The Wall Street Crash of 1929 triggered the Great Depression , which President Franklin D. Roosevelt responded to with

5809-547: The ArmaLite AR-15 was originally designed to replace the M14 rifle in the Vietnam War . The AR-15 is closely related to the military M16 and M4 carbine rifles, which all share the same core design. Invented by infantry rifle designer Eugene Stoner in 1956 for use in the 7.62 NATO caliber ArmaLite AR-10 battle rifle , the design features a gas-operated , rotating bolt combined with an integral piston (instead of

5966-553: The Atlantic slave trade . The original Thirteen Colonies that would later found the United States were administered as possessions of Great Britain , and had local governments with elections open to most white male property owners . The colonial population grew rapidly, eclipsing Native American populations; by the 1770s, the natural increase of the population was such that only a small minority of Americans had been born overseas. The colonies' distance from Britain allowed for

6123-552: The Colt AR-15 . After Colt's patents expired in 1977, an active marketplace emerged for other manufacturers to produce and sell their own semi-automatic AR-15–style rifles. Some versions of the AR-15 were classified as " assault weapons " and banned under the Federal Assault Weapons Ban in 1994 within the United States . This act expired in 2004. In 2009, the term "modern sporting rifle" was coined by

6280-563: The Crandon shooting , according to Mother Jones ' s mass shooting database. Gun expert Dean Hazen and mass murder researcher Pete Blair think that mass shooters' gun choices have less to do with the AR-15's specific characteristics but rather with familiarity and a copycat effect . According to the National Shooting Sports Foundation, there were an estimated 24.4 million AR-15s in private circulation in

6437-549: The Environmental Performance Index . The country joined the Paris Agreement on climate change in 2016 and has many other environmental commitments. The United States is a federal republic of 50 states and a separate federal capital district, Washington, D.C. It also asserts sovereignty over five unincorporated territories and several uninhabited island possessions . The U.S. is

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6594-500: The Federal Bureau of Investigation (FBI) and the U.S. Marshals Service have national jurisdiction and specialized duties, such as protecting civil rights , national security and enforcing U.S. federal courts ' rulings and federal laws. State courts conduct most civil and criminal trials, and federal courts handle designated crimes and appeals of state court decisions . There is no unified "criminal justice system" in

6751-720: The Great Lakes , Mississippi River and Gulf of Mexico . British colonization of the East Coast began with the Virginia Colony (1607) and Plymouth Colony (1620). The Mayflower Compact and the Fundamental Orders of Connecticut established precedents for representative self-governance and constitutionalism that would develop throughout the American colonies. While European settlers in what

6908-719: The Great Lakes region and along the Eastern Seaboard , while the Hohokam culture and Ancestral Puebloans inhabited the southwest . Native population estimates of what is now the United States before the arrival of European immigrants range from around 500,000 to nearly 10 million. Christopher Columbus began exploring the Caribbean for Spain in 1492, leading to Spanish-speaking settlements and missions from Puerto Rico and Florida to New Mexico and California . France established its own settlements along

7065-691: The MAS-36 , another bolt action, despite the various semi-automatic rifles designed between 1918 and 1935. Other nations experimented with self-loading rifles during the interwar period, including the United Kingdom , which had intended to replace the bolt-action Lee–Enfield with a self-loading rifle, but this plan had to be discarded when the Second World War became imminent, shifting its emphasis to speeding up re-armament with existing weapons. In Springfield, Massachusetts , John Garand ,

7222-596: The Midwest . At the same time, about one million French Canadians migrated from Quebec to New England . During the Great Migration , millions of African Americans left the rural South for urban areas in the North. Alaska was purchased from Russia in 1867. The Compromise of 1877 effectively ended Reconstruction and white supremacists took local control of Southern politics . African Americans endured

7379-720: The Mondragón rifle , designated the M1908. The rifle was used by Mexican forces in the Mexican Revolution , making Mexico the first nation to use a semi-automatic rifle in battle, in 1911. Shortly after the Mondragón rifle was produced, France had its own semi-automatic rifle, the Fusil Automatique Modele 1917 . It is a locked breech, gas-operated action which is similar in its mechanical principles to

7536-688: The National Park Service and other agencies. About 28% of the country's land is publicly owned and federally managed, primarily in the Western States . Most of this land is protected , though some is leased for commercial use, and less than one percent is used for military purposes. Environmental issues in the United States include debates on non-renewable resources and nuclear energy , air and water pollution , biodiversity , logging and deforestation , and climate change . The U.S. Environmental Protection Agency (EPA)

7693-582: The National Shooting Sports Foundation for its survey that year as a marketing term used by the firearms industry to describe modular semi-automatic rifles including AR-15s. Today, nearly every major firearm manufacturer produces its own generic AR-15–style rifle. As Colt continues to own and use the AR-15 trademark for its line of AR-15 variants , other manufacturers must use their own model numbers and names to market their AR-15–style rifles for commercial sale. Under US law,

7850-596: The New Deal , a series of sweeping programs and public works projects combined with financial reforms and regulations . All were intended to protect against future economic depressions. Initially neutral during World War II , the U.S. began supplying war materiel to the Allies of World War II in March 1941 and entered the war in December after the Empire of Japan 's attack on Pearl Harbor . The U.S. developed

8007-778: The Organization of American States and the United States–Mexico–Canada Free Trade Agreement . In South America, Colombia is traditionally considered to be the closest ally of the United States. The U.S. exercises full international defense authority and responsibility for Micronesia , the Marshall Islands , and Palau through the Compact of Free Association . It has increasingly conducted strategic cooperation with India , but its ties with China have steadily deteriorated. Since 2014,

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8164-648: The Pentium microprocessor in accordance with Moore's law , rechargeable lithium-ion batteries , the first gene therapy trial, and cloning either emerged in the U.S. or were improved upon there. The Human Genome Project was formally launched in 1990, while Nasdaq became the first stock market in the United States to trade online in 1998. In the Gulf War of 1991, an American-led international coalition of states expelled an Iraqi invasion force that had occupied neighboring Kuwait . The September 11 attacks on

8321-744: The Port Arthur massacre , the worst single-person shooting incident in Australian history, the country enacted the National Firearms Agreement in 1996, restricting the private ownership of semi-automatic rifles, semi-automatic shotguns, and pump action shotguns. ( Category D ). As a result of the Christchurch mosque shootings with an AR-15 during Friday Prayer on March 15, 2019, the New Zealand government enacted

8478-591: The Spanish–American War . (The Philippines was granted full independence from the U.S. on July 4, 1946, following World War II. Puerto Rico and Guam have remained U.S. territories.) American Samoa was acquired by the United States in 1900 after the Second Samoan Civil War . The U.S. Virgin Islands were purchased from Denmark in 1917. The United States entered World War I alongside

8635-478: The U.S. Army specifications. The resulting Semi-Automatic, Caliber .30, M1 Rifle was patented by Garand in 1932, approved by the U.S. Army on January 9, 1936, and went into mass production in 1940. Thus, in 1936, the American M1 Garand rifle became the first gas-operated semi-automatic rifle to be adopted by a country as their standard-issue service rifle . General George S. Patton described

8792-623: The United States ( U.S. ) or America , is a country primarily located in North America . It is a federal union of 50 states and a federal capital district, Washington, D.C. The 48 contiguous states border Canada to the north and Mexico to the south, with the states of Alaska to the northwest and the archipelagic Hawaii in the Pacific Ocean . The United States also asserts sovereignty over five major island territories and various uninhabited islands . The country has

8949-596: The Winchester Repeating Arms Company introduced the first low power blowback (shell operated) semi-automatic rimfire and centerfire rifles. The Winchester Model 1903 and Winchester Model 1905 operated on the principle of blowback to function semi-automatically. Designed by T.C. Johnson , the Model 1903 achieved commercial success and continued to be manufactured until 1932, when the Winchester Model 63 replaced it. By

9106-700: The cotton gin made the institution increasingly profitable for Southern elites . This sectional conflict regarding slavery culminated in the American Civil War (1861–1865). Eleven slave states seceded and formed the Confederate States of America , while the other states remained in the Union . War broke out in April 1861 after the Confederates bombarded Fort Sumter . After

9263-416: The end of the Cold War in 1991, the U.S. emerged as the world's sole superpower , wielding significant geopolitical influence globally . The U.S. national government is a presidential constitutional federal republic and liberal democracy with three separate branches : legislative , executive , and judicial . It has a bicameral national legislature composed of the House of Representatives ,

9420-413: The fall of communism and the collapse of the Soviet Union , which marked the end of the Cold War and left the United States as the world's sole superpower . The 1990s saw the longest recorded economic expansion in American history , a dramatic decline in U.S. crime rates , and advances in technology . Throughout this decade, technological innovations such as the World Wide Web , the evolution of

9577-400: The global economy in 2023. It possesses by far the largest amount of wealth of any country and has the highest disposable household income per capita among OECD countries. The U.S. ranks among the world's highest in economic competitiveness , productivity , innovation , human rights , and higher education . Its hard power and cultural influence have a global reach. The U.S. is

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9734-408: The "most beloved and most vilified rifles" in the United States, according to The New York Times ; the rifles have gained infamy due in part to their use in high-profile mass shootings . Promoted as "America's rifle" by the National Rifle Association of America , their popularity is partially attributable to active restrictions , or proposals to ban or restrict them. They are emblematic as being on

9891-406: The 1775 Battles of Lexington and Concord , igniting the American Revolutionary War . At the Second Continental Congress , the colonies appointed George Washington commander-in-chief of the Continental Army , and created a committee that named Thomas Jefferson to draft the Declaration of Independence . Two days after passing the Lee Resolution to create an independent nation the Declaration

10048-461: The 1990s, sales of AR-15–style rifles increased dramatically, partly as a result of the introduction of the flat top upper receiver (M4 variant) which allowed scopes and sighting devices to be easily mounted as well as new features such as free floating hand guards that increased accuracy. While only a handful of companies were manufacturing these rifles in 1994, by the 21st century the number of AR-15–style rifles had more than doubled. From 2000 to 2015,

10205-466: The 2010s, political polarization in the country increased between liberal and conservative factions. This polarization was capitalized upon in the January 2021 Capitol attack , when a mob of insurrectionists entered the U.S. Capitol and sought to prevent the peaceful transfer of power in an attempted self-coup d'état . The United States is the world's third-largest country by total area behind Russia and Canada. The 48 contiguous states and

10362-427: The 5.56×45mm NATO cartridge impose an overall length limit and diameter limits when adapting modules for other cartridges included in this list of AR platform cartridges . The same magazine in the lower receiver group may hold differing numbers of different cartridges. Most firearm-related homicides in the United States involve handguns . A 2019 Pew Research study found that 3% of US gun deaths were caused by rifles,

10519-478: The AR-15 safety is an improvement over traditional bolt action hunting rifles. Many states require hunters to use reduced-capacity magazines. If a hunter misses with a first shot, the self-loading feature enables rapid follow-up shots against dangerous animals like feral pigs or rapidly moving animals like jackrabbits . Hunters shooting larger game animals often use upper receivers and barrels adapted for larger cartridges or heavier bullets. Several states prohibit

10676-426: The American West have an alpine climate . The climate is arid in the Southwest, Mediterranean in coastal California , and oceanic in coastal Oregon , Washington , and southern Alaska . Most of Alaska is subarctic or polar . Hawaii , the southern tip of Florida and U.S. territories in the Caribbean and Pacific are tropical . States bordering the Gulf of Mexico are prone to hurricanes, and most of

10833-443: The Austrian 11×58mmR M/77 ), such as insufficient velocity and excessive fouling . Automatic firearms would only become feasible after smokeless powder became widespread. Mannlicher designs served as a basis for several future weapons, such as Browning machine guns ( M1917 , M1919, and M2 ). Mannlicher produced smokeless powder versions of his guns, beginning in the early 1890s, until his death in 1904, . In 1903 and 1905,

10990-436: The Colt AR-15 were slow, primarily due to its fixed sights and carry handle that made scopes difficult to mount and awkward to use. Military development of compact military AR-15 carbines encouraged production of a 16-inch (41 cm) barreled civilian SP1 carbine with a collapsible buttstock beginning in 1977. These carbines have become popular for police use in confined urban spaces, and the collapsible buttstock compensates for

11147-420: The Declaration of Independence on July 4, 1776. The term "United States" and the initialism "U.S.", used as nouns or as adjectives in English, are common short names for the country. The initialism "USA", a noun, is also common. "United States" and "U.S." are the established terms throughout the U.S. federal government , with prescribed rules. In English, the term "America" rarely refers to topics unrelated to

11304-573: The District of Columbia occupy a combined area of 3,119,885 square miles (8,080,470 km ). The coastal plain of the Atlantic seaboard gives way to inland forests and rolling hills in the Piedmont plateau region. The Appalachian Mountains and the Adirondack massif separate the East Coast from the Great Lakes and the grasslands of the Midwest . The Mississippi River System ,

11461-573: The Elder concluded that major military resources needed to be devoted to North America to win the war against France. For the first time, the continent became one of the main theaters of what could be termed a " world war ". The British colonies' position as an integral part of the British Empire became more apparent during the war, with British military and civilian officials becoming a more significant presence in American life. The war increased

11618-683: The January 1863 Emancipation Proclamation , many freed slaves joined the Union army . The war began to turn in the Union's favor following the 1863 Siege of Vicksburg and Battle of Gettysburg , and the Confederacy surrendered in 1865 after the Union's victory in the Battle of Appomattox Court House . The Reconstruction era followed the war. After the assassination of President Abraham Lincoln , Reconstruction Amendments were passed to protect

11775-648: The M1 Garand as " the greatest battle implement ever devised. " It replaced the bolt-action M1903 Springfield and became the standard infantry rifle known as the Garand Rifle . During World War II , over 4,000,000 M1 rifles were manufactured. The Soviet AVS-36 , SVT-38, and SVT-40 , as well as the German Gewehr 43 , were semi-automatic gas-operated rifles issued during World War II in relatively small numbers. In practice, they did not replace

11932-483: The M1 Garand was ultimately adapted to fire the .30-06 Springfield cartridge at the insistence of General Douglas MacArthur , most subsequent self-loading rifles for infantry use have been chambered for less powerful cartridges to reduce weight, making the service rifles easier to carry. Target shooting has a long history, predating the firearm. As weapons that demanded user accuracy developed, so did their usage in competitions. Today, semi-automatic rifles are one of

12089-540: The Model 1905 and Model 1907 saw limited military and police use. In 1883, two Danish inventors, Madsen and Rasmussen, began developing recoil-operated, self-loading firearm designs. By 1887, they had created a functional prototype, which was later designated the M1888 Forsøgsrekylgevær . This rifle underwent testing by the Danish military, but it was ultimately rejected for military adoption. Following

12246-611: The Rocky Mountains, the Yellowstone Caldera , is the continent's largest volcanic feature. In 2021, the United States had 8% of global permanent meadows and pastures and 10% of cropland. With its large size and geographic variety, the United States includes most climate types. East of the 100th meridian , the climate ranges from humid continental in the north to humid subtropical in the south. The western Great Plains are semi-arid . Many mountainous areas of

12403-647: The U.S. has become a key ally of Ukraine ; it has also provided the country with significant military equipment and other support in response to Russia's 2022 invasion . The president is the commander-in-chief of the United States Armed Forces and appoints its leaders, the secretary of defense and the Joint Chiefs of Staff . The Department of Defense , which is headquartered at the Pentagon near Washington, D.C., administers five of

12560-661: The U.S. territories." Despite disparate systems of confinement, four main institutions dominate: federal prisons , state prisons , local jails, and juvenile correctional facilities . Federal prisons are run by the Federal Bureau of Prisons and hold people who have been convicted of federal crimes, including pretrial detainees. State prisons, run by the official department of correction of each state, hold sentenced people serving prison time (usually longer than one year) for felony offenses. Local jails are county or municipal facilities that incarcerate defendants prior to trial; they also hold those serving short sentences (typically under

12717-408: The United Kingdom and Australia. The semi-automatic civilian AR-15 was introduced by Colt in 1963. The primary distinction between the civilian semi-automatic rifles and the military assault rifles is select fire . Military models are produced with multiple firing modes: semi-automatic fire, fully automatic fire mode and/or burst fire mode, in which the rifle fires several rounds in succession when

12874-464: The United States and the peaceful transfer of power , respectively. The Louisiana Purchase of 1803 from France nearly doubled the territory of the United States. Lingering issues with Britain remained , leading to the War of 1812 , which was fought to a draw. Spain ceded Florida and its Gulf Coast territory in 1819. In the late 18th century, American settlers began to expand westward , many with

13031-831: The United States entered the Cold War, where geopolitical tensions between the U.S. and the Soviet Union led the two countries to dominate world affairs . The U.S. utilized the policy of containment to limit the USSR's sphere of influence, and prevailed in the Space Race , which culminated with the first crewed Moon landing in 1969. Domestically, the U.S. experienced economic growth , urbanization , and population growth following World War II . The civil rights movement emerged, with Martin Luther King Jr. becoming

13188-666: The United States has operated as a de facto two-party system , though the parties in that system have been different at different times. The two main national parties are presently the Democratic and the Republican . The former is perceived as relatively liberal in its political platform while the latter is perceived as relatively conservative . In the American federal system , sovereign powers are shared between two levels of elected government: national and state. People in

13345-593: The United States in 2001 by the pan-Islamist militant organization al-Qaeda led to the war on terror , and subsequent military interventions in Afghanistan and Iraq . The cultural impact of the attacks was profound and long-lasting. The U.S. housing bubble culminated in 2007 with the Great Recession , the largest economic contraction since the Great Depression. Coming to a head in

13502-518: The United States in 2020. According to a 2021 Georgetown University poll of gun owners in the US, 24.6 million persons have an AR-15 or a comparable firearm in their possession. On July 13, 2024, at a Trump rally in Butler , Pennsylvania , 20-year-old Thomas Matthew Crooks used an AR-15–style rifle in a assassination attempt on former president Donald Trump . Following the use of a Colt AR-15 rifle in

13659-656: The United States of America to Spain" to seek assistance in the Revolutionary War effort. The first known public usage is an anonymous essay published in the Williamsburg newspaper, The Virginia Gazette , on April 6, 1776. By June 1776, the "United States of America" appeared in the Articles of Confederation and the Declaration of Independence . The Second Continental Congress adopted

13816-593: The United States, despite the usage of "the Americas " as the totality of North and South America. "The States" is an established colloquial shortening of the name, used particularly from abroad; "stateside" is the corresponding adjective or adverb. The first inhabitants of North America migrated from Siberia across the Bering land bridge about 12,000 years ago; the Clovis culture , which appeared around 11,000 BC,

13973-624: The United States, except Iran , North Korea , and Bhutan . Though Taiwan does not have formal diplomatic relations with the U.S., it maintains close unofficial relations. The United States regularly supplies Taiwan with military equipment to deter potential Chinese aggression. Its geopolitical attention also turned to the Indo-Pacific when the United States joined the Quadrilateral Security Dialogue with Australia, India, and Japan. The United States has

14130-509: The United States. The American prison system is largely heterogenous, with thousands of relatively independent systems operating across federal, state, local, and tribal levels. In 2023, "these systems [held] almost 2 million people in 1,566 state prisons, 98 federal prisons, 3,116 local jails, 1,323 juvenile correctional facilities, 181 immigration detention facilities, and 80 Indian country jails, as well as in military prisons , civil commitment centers, state psychiatric hospitals, and prisons in

14287-458: The additional auto-sear that holds it back until the bolt carrier group is fully in battery, when the automatic fire is selected. Using a portion of the select fire parts in a semi-automatic rifle will not enable a select fire option (this requires a registered part with the ATF ). Lower receivers that are select-fire are identified by a pinhole above the safety/mode selection switch. As designed by Colt,

14444-574: The additional thickness of body armor . The shorter barrel reduced bullet velocity by about five percent, and bullet energy by about 10%. The shorter barrel required moving the gas port closer to the chamber, exposing the self-loading system to higher pressures and temperatures which increased stress on moving parts like the bolt lugs and extractor. Although Colt offered a heavier 20-inch (51 cm) barrel for improved accuracy beginning in 1986, increased barrel weight may impair ergonomic balance; so shorter barrels have dominated recent rifle production. In

14601-676: The bolt action Karabiner 98k . Ultimately, automatic rifles would become standard in military usage, as their firepower was superior to that of a semi-automatic rifle. However, both semi-automatic and bolt action rifles are still widely used today in military service in specific roles, such as designated marksman rifles where the greater accuracy compared to automatic rifles is valued. Furthermore, to accommodate for this greater firepower, battle rifles were mostly replaced by assault rifles , whose lighter bullets allowed more ammunition to be carried at once. Where semi-automatic rifles continue to be used, they are usually in higher calibers, such as

14758-512: The bolt-action rifle as a standard infantry weapon of their respective nations— Germany produced 402,000 Gewehr 43 rifles, and over 14,000,000 of the Kar98k . Another gas-operated semi-automatic rifle developed toward the end of World War II was the SKS . Designed by Sergei Gavrilovich Simonov in 1945, it came equipped with a bayonet and could be loaded with ten rounds, using a stripper clip . It

14915-444: The buffer system is wholly contained in the upper receiver, and therefore does not use the buffer tube, which allows for firing while the stock is in the folded position, or removal of the stock altogether. The standard design includes a gas block and tube to vent burnt powder gas back into the bolt carrier assembly where it expands in a variable volume chamber forcing the bolt open to eject the spent cartridge case. The buffer spring in

15072-477: The buttstock then pushes the bolt closed after picking up a new cartridge from the magazine. This Stoner bolt and carrier piston system has the disadvantage of venting un-burned smokeless powder residue into the receiver where it may ultimately accumulate in quantities causing malfunctions. Some AR-15–style rifles use an alternative short-stroke gas piston design borrowed from the ArmaLite AR-18 , where

15229-543: The cartridge energy being used to reload, can give the advantage of reduced recoil . Reduced recoil helps keep the rifle on target for successive shots, improving overall accuracy. A self-loading mechanism, tuned for specific cartridge dimensions and power, may fail to reload dirty or bent cartridges that would otherwise fire. It can also struggle to extract low-power training cartridges or may be damaged by high-power rounds. Some rifles require lubricated cartridges, making them prone to collecting dirt. Reliability issues in

15386-713: The chest, neck, or face of a left handed shooter . When the M16A2 was adopted by the Army in 1986, it incorporated a built-in brass deflector to keep ejected cartridges from hitting the user. Most civilian variants also copy that feature. The modular design of AR-15–style rifles has encouraged several manufacturers to offer specialized parts including leftward ejecting upper receivers and left-handed bolts/bolt carriers for converting right-handed AR-15–style rifles for left-handed use. Ambidextrous lower receivers, magazine releases, and safety selectors have also been produced, allowing release of

15543-457: The contiguous United States are in the State of California, about 84 miles (135 km) apart. At an elevation of 20,310 feet (6,190.5 m), Alaska's Denali is the highest peak in the country and continent. Active volcanoes are common throughout Alaska's Alexander and Aleutian Islands , and Hawaii consists of volcanic islands. The supervolcano underlying Yellowstone National Park in

15700-556: The country's GDP. The U.S. has 42% of the world's nuclear weapons —the second-largest share after Russia. The United States has the third-largest combined armed forces in the world, behind the Chinese People's Liberation Army and Indian Armed Forces . The military operates about 800 bases and facilities abroad, and maintains deployments greater than 100 active duty personnel in 25 foreign countries. State defense forces (SDFs) are military units that operate under

15857-469: The country's territory would expand with the admission of new states , rather than the expansion of existing states. The U.S. Constitution was drafted at the 1787 Constitutional Convention to overcome the limitations of the Articles. It went into effect in 1789, creating a federal republic governed by three separate branches that together ensured a system of checks and balances . George Washington

16014-399: The default direct impingement/internal-piston based operating system, as insufficient gas pressure or volume is produced by the round to cycle the action, or the simpler blowback system is sufficient and may allow removal of the rear buffer tube and spring. Some AR-15–style rifles limit use of detachable magazines to comply with state regulations. Nearly all versions of the civilian AR-15 have

16171-713: The development of self-governance, and the First Great Awakening , a series of Christian revivals , fueled colonial interest in religious liberty . For a century, the American colonists had been providing their own troops and materiel in conflicts with indigenous peoples allied with Britain's colonial rivals , especially France, and the Americans had begun to develop a sense of self-defense and self-reliance separate from Britain. The French and Indian War (1754–1763) took on new significance for all North American colonists after Parliament under William Pitt

16328-414: The dispossession of native inhabitants . As more states were admitted , a North–South division over slavery led to the secession of the Confederate States of America , which fought states remaining in the Union in the 1861–1865 American Civil War . With the victory and preservation of the United States, slavery was abolished nationally . By 1900, the country had established itself as a great power ,

16485-440: The early 20th century, several manufacturers had introduced semi-automatic .22 rifles, including Winchester , Remington , Fabrique Nationale , and Savage Arms , all using the direct blowback system of operation. Winchester introduced a .351 Winchester Self-Loading semi-automatic rifle, the Model 1907, as an upgrade to the Model 1905, utilizing a blowback system of operation, offering more power than its .22 counterpart. Both

16642-580: The environment for labor unions to begin to flourish . This period eventually ended with the advent of the Progressive Era , which was characterized by significant reforms. Pro-American elements in Hawaii overthrew the Hawaiian monarchy ; the islands were annexed in 1898. That same year, Puerto Rico , the Philippines , and Guam were ceded to the U.S. by Spain after the latter's defeat in

16799-541: The federal government often applied policies of Indian removal or assimilation . The Trail of Tears (1830–1850) was a U.S. government policy that forcibly removed and displaced most Native Americans living east of the Mississippi River to lands far to the west. These and earlier organized displacements prompted a long series of American Indian Wars west of the Mississippi. The Republic of Texas

16956-543: The first nuclear weapons and used them against the Japanese cities of Hiroshima and Nagasaki in August 1945, ending the war. The United States was one of the " Four Policemen " who met to plan the post-war world , alongside the United Kingdom , Soviet Union , and China . The U.S. emerged relatively unscathed from the war, with even greater economic power and international political influence . After World War II,

17113-500: The first semi-automatics sold on the civilian market. Semi-automatic rifles are sometimes used for self-defense . Most semi-automatic rifles are rather lightweight and simple to operate, without compromising accuracy. Range-adjustable sights are also common, allowing their use in different environments. Johnson, Melvin M. (1944). Rifles and Machine Guns . New York: William Morrow and Company. United States The United States of America ( USA ), commonly known as

17270-745: The first settlement of the Thirteen Colonies in Virginia in 1607. Clashes with the British Crown over taxation and political representation sparked the American Revolution , with the Second Continental Congress formally declaring independence on July 4, 1776. Following its victory in the 1775–1783 Revolutionary War , the country continued to expand westward across North America , resulting in

17427-529: The frontline of the debate over U.S. gun control . The "AR" in AR-15 stands for "ArmaLite Rifle", and "AR-15" is most-commonly used to refer only to the civilian semi-automatic variants of the rifle which lack the fully automatic function. A common misconception is that "AR" is an abbreviation for " assault rifle " or " automatic rifle ", perhaps because of the weapon's inclusion in the Federal Assault Weapons Ban in 1994, or because

17584-463: The integration of Army National Guard units and personnel into the U.S. Army and (since 1947) the U.S. Air Force. There are about 18,000 U.S. police agencies from local to national level in the United States. Law in the United States is mainly enforced by local police departments and sheriff departments in their municipal or county jurisdictions. The state police departments have authority in their respective state , and federal agencies such as

17741-545: The legal definition set forth in 27 CFR § 479.11, with some lower courts disagreeing while a 2021 case from the Eighth Circuit found otherwise. While most earlier breech-loading rifles had a single receiver housing both the trigger and reloading mechanism, an innovative feature of the AR-15 was modular construction to simplify substitution of parts and avoid need for arsenal facilities for most repairs of malfunctioning military rifles. A distinctive two-part receiver

17898-623: The magazine from the left side, closing of the bolt from the right side, and operation of the safety from the right side, respectively. The AR-15 is nominally chambered in .223 Remington or 5.56×45mm NATO , with the .223 Wylde chamber allowing for the safe chambering of both, but many variants have been produced in different calibers such as .22 LR (sometimes referred to as an AR-22 ), 7.62×39mm , 9×19mm Parabellum , 6.5mm Grendel , and shotgun calibers. Some of these firearms chambered in smaller calibers such as 9mm or .22 utilize simple blowback or delayed blowback operating principles instead of

18055-424: The magazine well. Lower receivers may be bought "stripped"—a single solid part and legally a firearm in the United States, albeit nonfunctional, with no fire control group or lower parts kit installed. End users may install their own choice of fire control group and lower parts kit. The lower receiver holds the trigger assembly including the hammer , and is the attachment point for the buttstock . The lower receiver

18212-515: The mechanism can negate the advantage of faster firing , potentially lowering the rate of fire compared to manually loaded rifles if not designed for easy manual reloading. The United Kingdom regarded the reliable rate of fire from manually loaded rifles to be nearly as high as self-loading rifles as recently as World War II . Semi-automatic rifles are uniquely susceptible to slamfire malfunctions caused by abrupt cartridge acceleration during self-loading. Slamfire discharges are unlikely to hit

18369-482: The military draft (leading to the end of conscription in 1973) and wide opposition to U.S. intervention in Vietnam (with the U.S. totally withdrawing in 1975). A societal shift in the roles of women was significantly responsible for the large increase in female paid labor participation during the 1970s, and by 1985 the majority of American women aged 16 and older were employed. The late 1980s and early 1990s saw

18526-530: The military rejected the design in favor of the M14 . After most of the patents for the Colt AR-15 expired in 1977, many firearm manufacturers began to produce copies of the rifle under various names. While the patents are expired, Colt has retained the trademark to the AR-15 name and is the sole manufacturer able to label their firearms as such. From 1994 to 2004, the Federal Assault Weapons Ban restricted

18683-853: The more prominent firearms in sport shooting . There are various types of sport shooting, ranging from rapid fire shooting; target shooting, which is predominantly accuracy based; and distance shooting. Shooting clubs in America became increasingly commonplace in the 1830s, and have since grown in popularity. Semi-automatic rifles are commonly used in sport shooting events because of their accuracy, versatility, and their low weight, which has invited more people, specifically women and children, to compete as well. Semi-automatic rifles have grown in status among hunters. Many hunters are adopting semi-automatic rifles, particularly AR-15 style rifles to take advantage of their compact design and modularity, effectively making it easier to traverse rugged terrain while tracking

18840-612: The most attractive to the population are the most vulnerable. The U.S. is one of 17 megadiverse countries containing large numbers of endemic species : about 17,000 species of vascular plants occur in the contiguous United States and Alaska, and over 1,800 species of flowering plants are found in Hawaii, few of which occur on the mainland. The United States is home to 428 mammal species, 784 birds, 311 reptiles, 295 amphibians , and around 91,000 insect species. There are 63 national parks , and hundreds of other federally managed parks, forests, and wilderness areas , managed by

18997-662: The most violent, the California genocide of thousands of Native inhabitants, lasted into the early 1870s, just as additional western territories and states were created. During the colonial period, slavery had been legal in the American colonies , though the practice began to be significantly questioned during the American Revolution. States in the North enacted abolition laws , though support for slavery strengthened in Southern states , as inventions such as

19154-560: The number of manufacturers of AR-15–style rifles increased from 29 to an estimated 500. AR-15–style rifles are now available in a wide range of configurations and calibers from a large number of manufacturers. These configurations range from standard full-sizes rifles with 20-inch (51 cm) barrels, to short carbine-length models with 16-inch (41 cm) barrels, adjustable length stocks and optical sights, to long range target models with 24-inch (61 cm) barrels, bipods and high-powered scopes. In September 2019, Colt Firearms announced it

19311-506: The pins supporting the semi-auto trigger and hammer in the lower receiver are larger than those used in the military rifle to prevent interchangeability between semi-automatic and select-fire components. The pivot pin may also be slightly larger in diameter. The first version produced for commercial sale by Colt was the SP1 model AR-15 Sporter in .223 Remington, with a 20-inch (51 cm) barrel and issued with five-round magazines. Initial sales of

19468-408: The policy of redlining later adopted by the federal Home Owners' Loan Corporation . An explosion of technological advancement accompanied by the exploitation of cheap immigrant labor led to rapid economic expansion during the late 19th and early 20th centuries , allowing the United States to outpace the economies of England, France, and Germany combined. This fostered the amassing of power by

19625-574: The primary colonial grievances was a denial of their rights as Englishmen , particularly the right to representation in the British government that taxed them . To demonstrate their dissatisfaction and resolve, the First Continental Congress met in 1774 and passed the Continental Association , a colonial boycott of British goods that proved effective. The British attempt to then disarm the colonists resulted in

19782-407: The primary weapons used in half of the 10 deadliest mass shootings in modern American history: the 2012 Sandy Hook Elementary School shooting , the 2017 Las Vegas shooting , the 2017 Sutherland Springs church shooting , the 2018 Parkland high school shooting , and the 2022 Robb Elementary School shooting . The first time wherein an AR-15–style rifle was used in a mass shooting was in 2007, during

19939-789: The rifles are owned in the United States. The National Shooting Sports Foundation estimated in 2016 that approximately 5 million to 10 million AR-15–style rifles existed in the U.S. within the broader total of the 300 million firearms owned by Americans. Many hunters prefer using AR-15–style rifles because of their versatility, accuracy, wide variety of available features, and wide variety of calibers (see below). Collapsible stocks are convenient for hunters who pack their rifles into remote hunting locations or for length of pull adjustments to fit any sized hunter. Construction with lightweight polymers and corrosion -resistant alloys makes these rifles preferred for hunting in moist environments with less concern about rusting or warping wood stocks. Positioning of

20096-399: The right shoulder while sighting with the right eye and using a finger of the right hand to pull the trigger. Right-side ejection is a disadvantage for the third of the population whose left eye is dominant , and for the tenth of the population who are left handed , because holding these rifles against their left shoulder for maximum accuracy may cause the rifle to eject hot spent cases toward

20253-515: The rights of African Americans . National infrastructure, including transcontinental telegraph and railroads , spurred growth in the American frontier . From 1865 through 1917 an unprecedented stream of immigrants arrived in the United States, including 24.4 million from Europe. Most came through the port of New York City , and New York City and other large cities on the East Coast became home to large Jewish , Irish , and Italian populations, while many Germans and Central Europeans moved to

20410-458: The risk of slam-firing , the HK416 and its civilian variant MR556 feature a proprietary firing pin safety in the bolt. Such firing pin safeties may obstruct the upper from working with standard AR-15-type full height hammers located in the fire control group of the lower. Most rifles eject spent cartridges from the right side of the receiver away from right-handed shooters who place the butt against

20567-614: The rocky Great Basin and Chihuahua , Sonoran , and Mojave deserts. In the northwest corner of Arizona , carved by the Colorado River over millions of years, is the Grand Canyon , a steep-sided canyon and popular tourist destination known for its overwhelming visual size and intricate, colorful landscape. The Sierra Nevada and Cascade mountain ranges run close to the Pacific coast . The lowest and highest points in

20724-532: The sale of the Colt AR-15 and some derivatives in the United States, although it did not affect rifles with fewer listed features. After the phrase " modern sporting rifles ", to be used synonymously with the AR-15 style, was coined in 2009 by the US National Shooting Sports Foundation (NSSF), a firearms trade association, it was quickly adopted by much of the industry. Beginning in the 2010s, AR-15–style rifles became one of

20881-477: The same lower receiver. These upper receiver groups may have differing barrel lengths and sights and may fire different cartridges. A hunter with a single lower receiver might have one upper receiver with a .223 Remington barrel and telescopic sight for varmint hunting in the open country and another upper receiver with a .458 SOCOM barrel and iron sights for big-game hunting in brushy woodland. The dimensions of upper and lower receivers originally designed for

21038-424: The select fire components, several features were changed. Parts changed include the lower receiver, bolt carrier, hammer, trigger, disconnector, and safety/mode selector. The semi-automatic bolt carrier has a longer lightening slot to prevent the bolt's engagement with an automatic sear. Due to a decrease in mass, the buffer spring is heavier. On the select-fire version, the hammer has an extra spur which interacts with

21195-573: The six service branches, which are made up of the U.S. Army , Marine Corps , Navy , Air Force , and Space Force . The Coast Guard is administered by the Department of Homeland Security in peacetime and can be transferred to the Department of the Navy in wartime. The United States spent $ 916 billion on its military in 2023, which is by far the largest amount of any country , making up 37% of global military spending and accounting for 3.4% of

21352-545: The sole authority of a state government. SDFs are authorized by state and federal law but are under the command of the state's governor . They are distinct from the state's National Guard units in that they cannot become federalized entities. A state's National Guard personnel, however, may be federalized under the National Defense Act Amendments of 1933 , which created the Guard and provides for

21509-543: The states are also represented by local elected governments , which are administrative divisions of the states. States are subdivided into counties or county equivalents , and further divided into municipalities . The District of Columbia is a federal district containing the U.S. capital, Washington, D.C. . The federal district is an administrative division of the federal government. Federally recognized tribes govern 326 Indian reservations . The United States has an established structure of foreign relations, and it has

21666-510: The structure and responsibilities of the national federal government and its relationship with the individual states. The U.S. Constitution is the world's oldest national constitution still in effect (from March 4, 1789). Composed of three branches, all headquartered in Washington, D.C., the federal government is the national government of the United States. It is regulated by a strong system of checks and balances . The three-branch system

21823-500: The subsequently manufactured American M1 Garand . The M1917 was fielded during the latter stages of World War I , where it did not receive a favorable reception among troops. However, its shortened and improved version, the Model 1918, was used more during the Moroccan Rif War from 1920 to 1926. Still, the bolt-action Lebel Model 1886 rifle remained the standard French infantry rifle until being replaced in 1936 by

21980-509: The target and may cause collateral damage . The time required for changing or reloading magazines can weaken the effectiveness of a rifle, as it imposes an effective duration limit on the continuous rate of fire of any rifle . High-capacity magazines increase the weight of the rifle and typically reduce feeding reliability due to the varying spring tension from a full to a nearly empty magazine. Detachable magazines in general are usually less durable than internal magazines. The complexity of

22137-516: The trigger is depressed. Most components are interchangeable between semi-auto and select fire rifles including magazines, sights, upper receiver, barrels and accessories. The military M4 carbine typically uses a 14.5-inch (37 cm) barrel. Civilian rifles commonly have 16-inch (41 cm) or longer barrels to comply with the National Firearms Act . To prevent a civilian semi-automatic AR-15 from being readily converted for use with

22294-671: The unsuccessful trials, the inventors developed a new design, known as the M1896 Flaadens Rekylgevær . This model was also tested by the Danish military, and this time it was found to be reliable. As a result, 60 units were procured for the Danish Navy, making it one of the earliest semi-automatic rifles to be officially adopted by a military force. In the final years of the 19th century and early 20th century, experiments and patents with gas-operated reloading were developed by Hiram Maxim and Richard Paulson as well

22451-550: The upper receiver or the barrel assembly. A handguard usually encloses the barrel and is attached to the upper receiver, and depending on the handguard, also attached to the barrel's gas block. AR-15–style rifles may have folding or collapsible stocks which reduce the overall length of the rifle when folded, although some designs of the stock folding device may not allow the firearm to be fired until unfolded, or only fire once until unfolded. A few manufacturers have made full upper receivers, or even "bufferless" bolt carrier systems where

22608-417: The use of .22 caliber cartridges like the .223 Remington on large game. Since the upper and lower receivers may be swapped between rifles, forensic firearm examination of bullets and spent cartridges may reveal distinguishing marks from the barrel and upper receiver group without identifying the lower receiver for which legal records may be available. An individual may use several upper receiver groups with

22765-458: The vast assortment of aftermarket parts and accessories available, AR-15–style rifles have also been referred to as "the Swiss Army knife of rifles", "Barbie Dolls for Guys", or "LEGOs for adults". These more or less interchangeable modules are a defining characteristic of AR-15–style rifles. The lower receiver includes the trigger guard in front of the detachable pistol grip , and behind

22922-582: The world's fourth-longest river system , runs predominantly north–south through the heart of the country. The flat and fertile prairie of the Great Plains stretches to the west, interrupted by a highland region in the southeast. The Rocky Mountains , west of the Great Plains, extend north to south across the country, peaking at over 14,000 feet (4,300 m) in Colorado . Farther west are

23079-583: The world's second-largest diplomatic corps as of 2024 . It is a permanent member of the United Nations Security Council , and home to the United Nations headquarters . The United States is a member of the G7 , G20 , and OECD intergovernmental organizations. Almost all countries have embassies and many have consulates (official representatives) in the country. Likewise, nearly all countries host formal diplomatic missions with

23236-461: The world's third-largest land area , largest exclusive economic zone , and third-largest population , exceeding 334 million. Its three largest metropolitan areas are New York , Los Angeles , and Chicago , and its three most populous states are California , Texas , and Florida . Paleo-Indians migrated across the Bering land bridge more than 12,000 years ago, and formed various civilizations and societies . British colonization led to

23393-444: The world's oldest surviving federation, and its presidential system of national government has been adopted, in whole or in part, by many newly independent states worldwide following their decolonization . It is a liberal representative democracy "in which majority rule is tempered by minority rights protected by law ". The Constitution of the United States serves as the country's supreme legal document , also establishing

23550-553: The world's tornadoes occur in the country , mainly in Tornado Alley . Overall, the United States receives more high-impact extreme weather incidents than any other country. Extreme weather became more frequent in the U.S. in the 21st century, with three times the number of reported heat waves as in the 1960s. In the American Southwest , droughts became more persistent and more severe. The regions considered as

23707-575: Was annexed in 1845, and the 1846 Oregon Treaty led to U.S. control of the present-day American Northwest . Victory in the Mexican–American War resulted in the 1848 Mexican Cession of California, Nevada, Utah, and much of present-day Colorado and the American Southwest . The California gold rush of 1848–1849 spurred a huge migration of white settlers to the Pacific coast, leading to even more confrontations with Native populations. One of

23864-457: Was a successor to earlier rifles that required manual cycling of the weapon after each shot, such as the bolt-action rifle or repeating rifles . The ability to automatically load the next round results in an increase in the rounds per minute the operator can fire. The main advantage of semi-automatic rifles is the ability to fire sequential shots in rapid succession without adjusting the aiming position to manually chamber cartridges . Engaging

24021-703: Was adopted on July 4, 1776. The political values of the American Revolution included liberty , inalienable individual rights ; and the sovereignty of the people ; supporting republicanism and rejecting monarchy , aristocracy , and all hereditary political power; civic virtue ; and vilification of political corruption . The Founding Fathers of the United States , who included Washington, Jefferson, John Adams , Benjamin Franklin , Alexander Hamilton , John Jay , James Madison , Thomas Paine , and many others, were inspired by Greco-Roman , Renaissance , and Enlightenment philosophies and ideas. The Articles of Confederation were ratified in 1781 and established

24178-439: Was discontinuing production of the AR-15 for the consumer market, citing "significant excess manufacturing capacity" across the industry and the company's "high-volume contracts" with military and police forces that were "absorbing all of Colt's manufacturing capacity for rifles". However, in 2020, Colt resumed production of the AR-15, following a surge in demand in the United States consumer market. Estimates vary as to how many of

24335-404: Was elected the country's first president under the Constitution, and the Bill of Rights was adopted in 1791 to allay skeptics' concerns about the power of the more centralized government. His resignation as commander-in-chief after the Revolutionary War and his later refusal to run for a third term as the country's first president established a precedent for the supremacy of civil authority in

24492-417: Was offered in .25 , .30 , .32 , and .35 caliber models. It gained some popularity among civilians as well as some law enforcement officials who appreciated the combination of a semi-automatic action and relatively powerful rifle cartridges. In 1936, the Model 81 superseded the Model 8, and was offered in .300 Savage as well as the original Remington calibers. In 1908, General Manuel Mondragón patented

24649-447: Was the first widely issued rifle to use the 7.62×39mm cartridge. By the end of World War II, however, semi-automatic rifles had been largely superseded in military usage by their fully automatic and select-fire counterparts - weapons such as the AK-47 , FN FAL and M16 limited the viability of widespread deployment of semi-automatic rifles. Gradually, military doctrine evolved to place less emphasis on individual marksmanship, as

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