149-552: A designated marksman rifle ( DMR ) is a modern scoped high- precision rifle used by infantry in the designated marksman (DM) role. It generally fills the engagement range gap between a service rifle and a dedicated sniper rifle , at around 300–600 metres (330–660 yd). DMRs are distinguished from sniper rifles in that they are semi-automatic to provide higher rates of fire (with some also having selective fire to switch to burst or automatic ) and have larger magazine capacities (10, 20, or 30 rounds depending on
298-408: A White-tailed deer buck by adjusting magnification until the area between the backbone and the brisket fits between the crosshairs and the top thick post of the reticle. Once that is done, the range be read from the scale printed on the magnification adjustment ring. Although FFP designs are not susceptible to magnification-induced errors, they have their own disadvantages. It's challenging to design
447-500: A mathematical formula "[Target size] ÷ [Number of mil intervals] × 1000 = Distance", the user can easily calculate the distance to a target, as a 1-meter object is going to be exactly 1 milliradian at a 1000-meter distance. For example, if the user sees an object known to be 1.8 meters tall as something 3 mils tall through the telescopic sight, the distance to that object will be 600 meters (1.8 ÷ 3 × 1000 = 600). Some milling reticles have additional marking patterns in
596-551: A night vision sight, among many other accessories. This kit was designed to be configurable (modular) for various missions, and the kit is currently in service with special operations units. In 2002, the Block II modification kit was adopted featuring two new upper receivers: the Special Purpose Receiver (SPR) with a 16 or 18 in (406 or 457 mm) barrel and Close Quarter Battle Receiver (CQBR) with
745-602: A scope informally, is an optical sighting device based on a refracting telescope . It is equipped with some form of a referencing pattern – known as a reticle – mounted in a focally appropriate position in its optical system to provide an accurate point of aim. Telescopic sights are used with all types of systems that require magnification in addition to reliable visual aiming, as opposed to non-magnifying iron sights , reflector (reflex) sights , holographic sights or laser sights , and are most commonly found on long-barrel firearms , particularly rifles, usually via
894-491: A scope mount . Similar devices are also found on other platforms such as artillery , tanks and even aircraft . The optical components may be combined with optoelectronics to add night vision or smart device features. The first experiments directed to give shooters optical aiming aids go back to the early 17th century. For centuries, different optical aiming aids and primitive predecessors of telescopic sights were created that had practical or performance limitations. In
1043-450: A zoom mechanism behind the erector lenses . Variable-power sights offer more flexibility when shooting at varying distances, target sizes and light conditions, and offer a relative wide field of view at lower magnification settings. The syntax for variable sights is the following: minimal magnification – maximum magnification × objective lens , for example "3-9×40" means a telescopic sight with variable magnification between 3× and 9×, and
1192-756: A 10.3 in (262 mm) barrel. M4A1s fitted with the SPR were designated by the Navy as the Mk 12 Special Purpose Rifle , a type of designated marksman rifle . M4A1s with the CQBR were designated the Mk 18 Mod 0. The Block II program then focused on component improvements to the M4A1, with the adoption of the heavier "SOCOM profile" barrel in 2004 and free-float Rail Interface System II (RIS-II) handguard from Daniel Defense in 2008. Owing to
1341-416: A 40 mm objective lens. The ratio between the maximum and minimum magnifications of a variable-power sight is known as its "zoom ratio". Confusingly, some older telescopic sights, mainly of German or other European manufacture, have a different classification where the second part of the designation refers to light-gathering power. In these cases, a 4×81 (4× magnification) sight would be presumed to have
1490-540: A back-up iron sight, forward pistol grip, empty magazine, and sling. Each carbine upgrade costs $ 240 per rifle, for a total cost of $ 120 million for half a million conversions. Three hundred conversions can be done per day to equip a brigade combat team per week, with all M4A1 conversions to be completed by 2019. In addition to upgrade kits, in April 2012, the U.S. Army announced it would begin purchasing over 120,000 M4A1 carbines to start reequipping front line units from
1639-429: A brighter sight picture than a 2.5×70 (2.5× magnification), but the objective lens diameter would not bear any direct relation to picture brightness, as brightness is affected also by the magnification factor. Typically objective lenses on early sights are smaller than modern sights, in these examples the 4×81 would have an objective 36 mm diameter and the 2.5×70 should be approximately 21 mm (relative luminosity
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#17327880272921788-535: A cased-telescoped (CT) ammunition-firing rifle for the program; FN Herstal submitted their HAMR IAR re-chambered in 6.8mm caliber; PCP Tactical submitted a modified Desert Tech MDRx ; SIG Sauer submitted a redesigned MCX variant known as the MCX-SPEAR. In early 2022, the program concluded, with SIG Sauer being declared the winner. Their rifle entry was designated the XM5 (later changed to XM7 to avoid confusion with
1937-445: A combination of the above, that are added to a crosshair to help with easier aiming. Many modern reticles are designed for (stadiametric) rangefinding purposes. Perhaps the most popular and well-known ranging reticle is the mil-dot reticle , which consists of a duplex crosshair with small dots marking each milliradian (or "mil") intervals from the center. An alternative variant uses perpendicular hash lines instead of dots, and
2086-405: A complex production process. The main tube of telescopic sights varies in size, material, the applied production process and surface finish. The typical outside diameters vary between 19.05 mm (0.75 in) and 40 mm (1.57 in), although 25.4 mm (1 in), 30 mm and recently 34 mm are by far the most common sizes. The internal diameter of the main tube influences
2235-662: A crisp tactile feedback corresponding to each graduation of turn, often accompanied by a soft but audible clicking sound. Each indexing increment is thus colloquially called a "click", and the corresponding angular adjustment of the optical axis is known as the click value . The most commonly seen click values are 1 ⁄ 4 MOA (often expressed in approximations as " 1 ⁄ 4 inch at 100 yards") and 0.1 mil (often expressed as "10 mm at 100 meters"), although other click values such as 1 ⁄ 2 MOA, 1 ⁄ 3 MOA or 1 ⁄ 8 MOA and other mil increments are also present on
2384-592: A detachable rail-mounted carrying handle, or anything else compatible with a MIL-STD-1913 picatinny rail . Other common accessories include the AN/PEQ-2 , AN/PEQ-15 multi-mode laser, AN/PEQ-16 Mini Integrated Pointing Illumination Module (MIPIM) , Trijicon TA01 and TA31 Advanced Combat Optical Gunsights (ACOG), EOTech 550 series holographic sights, and Aimpoint M68 Close Combat Optic . Visible and infrared lights of various manufacturers are commonly attached using various mounting methods. As with all versions of
2533-445: A first focal plane reticle expands and shrinks along with the rest of the image as the magnification is adjusted, while a second focal plane reticle would appear the same size and shape to the user as the target image grows and shrinks. In general, the majority of modern variable-power sights are SFP unless stated otherwise. Every European high-end telescopic sight manufacturer offers FFP reticles on variable power telescopic sights, since
2682-470: A fixed magnification factor of 10×, with a 50 mm objective lens. In general terms, larger objective lens diameters, due to their ability to gather a higher luminous flux , provide a larger exit pupil and hence provide a brighter image at the eyepiece . Most early telescopic sights were fixed-power and were in essence specially designed viewing telescopes. Telescopic sights with variable magnifications appeared later, and were varied by manually adjusting
2831-556: A flattop upper receiver. Variants of the carbine built by different manufacturers are also in service with many other foreign special forces units, such as the Australian Special Air Service Regiment (SASR). While the SASR uses weapons of essentially the same pattern built by Colt for export (Colt uses different models to separate weapons for the U.S. military and those for commercial/export purposes),
2980-489: A jam when his M16 was covered in mud after climbing out of a canal . The weapon was cleared and resumed firing with the next chambered round. Furthermore, a Marine chief warrant officer reported that there were no issues with his battalion 's 700 M4s and 350 M16s. The reliability of the M4 has increased as the design was upgraded. In 1990, the M4 was required to fire 600 mean rounds between stoppages using M855 ammunition. In 2013,
3129-542: A large difference from the last test with the M4 having 148 class 1 stoppages caused by rifle malfunctions and 148 class 1 stoppages caused by magazine stoppages. The full-size M16 rifle had 61 stoppages during the same extreme dust test. In early 2010, two journalists from the New York Times spent three months with soldiers and Marines in Afghanistan. While there, they questioned around 100 infantrymen about
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#17327880272923278-724: A light source to provide an illuminated reticle for low-light condition aiming. In sights such as the SUSAT or Elcan C79 Optical Sight tritium-illuminated reticles are used. The Trijicon Corporation, famous for their ACOG prism sights that are adopted by various assault infantry branches of the United States military , uses tritium in their combat and hunting-grade firearm optics. The tritium light source has to be replaced every 8–12 years, since it gradually loses brightness due to radioactive decay . M4 carbine The M4 carbine (officially Carbine, Caliber 5.56 mm, M4 )
3427-584: A long-eye relief (LER) telescopic sight is the German ZF41 which was used during World War II on Karabiner 98k rifles. An early example of a man-portable sight for low visibility/night use is the Zielgerät (aiming device) 1229 (ZG 1229), also known by its code name Vampir ("vampire"). The ZG 1229 Vampir was a Generation 0 active infrared night vision device developed for the Wehrmacht for
3576-529: A longer "mid length" gas system with its newer Upper Receiver Group-Improved (URG-I) modifications. As the modifications only affect the upper receiver assembly, rifles with the URG-I still retain the M4A1 designation. The M4's maneuverability makes it beneficial for non-infantry troops (vehicle crews, clerks and staff officers), as well as for close quarters battle . The M4, along with the M16A4, has mostly replaced
3725-593: A mid-length gas system. Although initially an Army program, the URG-I has seen use by other components of SOCOM as well. The GAU-5/A Aircrew Self Defense Weapon (ASDW) is an Air Force modified M4 with a detachable barrel and handguard assembly, folding pistol grip, and fold-down iron sights to enable compact packaging. This weapon is stowed in ejection seats of tactical aircraft and is intended to allow aircrew who egress in hostile environments to better defend themselves until rescue than existing handguns. The weapons entered service in 2018. Confusingly, this weapon shares
3874-472: A military M4, but with a 16-inch (41 cm) barrel. The Bushmaster M4 Type Carbine is a popular example. Civilian models are sometimes colloquially referred to as "M4gery" ( / ɛ m ˈ f ɔːr dʒ ər i / em- FOR -jə-ree , a portmanteau of "M4" and "forgery.") Colt had maintained that it retained sole rights to the M4 name and design, while other manufacturers had long maintained that Colt had been overstating its rights, and that "M4" had now become
4023-476: A multi-position telescoping stock or a fixed A2 or LE tactical stock. The M4 is a shorter and lighter variant of the M16A2 rifle, sharing much of the same operation mechanisms and has 80% parts commonality; the chief differences are a shorter barrel of 14.5 inches rather than 20 inches as well as a shortened receiver extension and buffer. Two fire control groups exist for the M4 family, the three-round burst for
4172-524: A receiver extension that is inline with the barrel. The gas system, bolt carrier, and bolt-locking design is ammunition specific, since it does not have an adjustable gas port or valve to adjust the weapon to various propellant and projectile or barrel length specific pressure behavior. The receiver is made of forged 7075-T6 aluminum, while the 14.5 in (368 mm) barrel, bolt, bolt carrier, and fire control group are made of steel; these components can be easily serviced and replaced by unit armories, enabling
4321-474: A reticle that is visible through the entire range of magnification: a reticle that looks fine and crisp at 24× magnification may be very difficult to see at 6×. On the other hand, a reticle that is easy to see at 6× may be too thick at 24× to make precision shots. Shooting in low light conditions also tends to require either illumination or a bold reticle, along with lower magnification to maximize light gathering. In practice, these issues tend to significantly reduce
4470-703: A round dot, small cross , diamond , chevron and/or circle in the center (in some prism sights and reflex / holographic sights ), or a pointed vertical bar in a " T "-like pattern (such as the famous "German #1" reticle used on the Wehrmacht ZF41 sights during the Second World War , or the SVD -pattern reticle used on the Soviet PSO-1 sights during the Cold War ) that essentially imitates
4619-480: A separate upper receiver for their M4A1 to enable greater mission flexibility. The SOPMOD program also introduced the Special Purpose Receiver (SPR), a 16-or-18 in (406-or-457 mm) barreled upper receiver that would be mated to an M4A1 lower receiver to allow the weapon to serve as a designated marksman rifle (DMR). Although originally intended as an upper receiver kit for the M4A1 like
Designated marksman rifle - Misplaced Pages Continue
4768-520: A series of changes to the M4 to Congress. Requested changes included an electronic round counter that records the number of shots fired, a heavier "SOCOM barrel", and possibly replacing the Stoner expanding gas system with a gas piston system. The heavier "SOCOM barrel" was first issued to special forces operators in the early 2000s to enable greater sustained automatic fire in certain immediate-action drills, although SOCOM itself would eventually return to
4917-595: A sight made by gunsmith Morgan James of Utica, New York . Chapman worked with James on the concepts and design of the Chapman-James sight. In 1855, optician William Malcolm of Syracuse, New York began producing his own telescopic sight, used an original design incorporating achromatic lenses such as those used in telescopes, and improved the windage and elevation adjustments. These Malcolm sights were between 3× and 20× magnification (possibly more). Malcolm's sights and those made by Vermont jeweller L. M. Amidon were
5066-781: A target of a known diameter of 16 inches fills just half of the total post-to-post distance (i.e. filling from sight center to post), then the distance to target is approximately 200 yards (180 m). With a target of a diameter of 16 inches that fills the entire sight picture from post to post, the range is approximately 100 yards. Other ranges can be similarly estimated accurately in an analog fashion for known target sizes through proportionality calculations. Holdover, for estimating vertical point of aim offset required for bullet drop compensation on level terrain, and horizontal windage offset, for estimating side to side point of aim offsets required for wind effect corrections, can similarly be compensated for through using approximations based on
5215-518: A telescope to a rifle as a sighting aid, but was unable to mount it sufficiently far forward to prevent the eyepiece impacting with the operator's eye during recoil . In the same year, James Lind and Captain Alexander Blair described a gun which included a telescopic sight. The first rifle sight was created in 1835 -1840. In the book The Improved American Rifle , written in 1844, British-American civil engineer John R. Chapman described
5364-417: A typical Leupold brand 16 minute of angle (MOA) duplex reticle (similar to image B) on a fixed-power telescopic sight, the distance from post to post, between the heavier lines of the reticle spanning the center of the sight picture, is approximately 32 inches (810 millimeters) at 200 yards (180 m), or, equivalently, approximately 16 inches (410 millimeters) from the center to any post at 200 yards. If
5513-732: Is a 5.56×45mm NATO assault rifle developed in the United States during the 1980s. It is a shortened version of the M16A2 assault rifle. The M4 is extensively used by the US military , with decisions to largely replace the M16 rifle in US Army (starting 2010) and US Marine Corps (starting 2016) combat units as the primary infantry weapon and service rifle . The M4 has been adopted by over 60 countries worldwide, and has been described as "one of
5662-506: Is a U.S. Army Special Operations Command (USASOC) program to further improve the durability and reliability of the SOPMOD Block II by introducing additional component improvements. First fielded in 2018, the main improvements are the lighter Geissele Mark 16 free-float rail that incorporates M-LOK as the mounting method and a Daniel Defense cold hammer-forged barrel that returns to the lighter "government" profile contour as well as
5811-409: Is better for clearing rooms than burst fire. A subvariant of the M4A1 uses a heavier barrel than the standard M4, as the regular M4 barrel, which can fire 6,000 rounds before requiring inspection for possible replacement, was not sufficient for the higher consumption of ammunition by SOCOM operators. The redesigned barrel, colloquially referred to as the "SOCOM barrel", has an increased diameter in
5960-409: Is essential that its brightness can be adjusted. A reticle that is too bright will cause glare in the operator's eye, interfering with their ability to see in low-light conditions. This is because the pupil of the human eye closes quickly upon receiving any source of light. Most illuminated reticles provide adjustable brightness settings to adjust the reticle precisely to the ambient light. Illumination
6109-406: Is etched onto one of the prism's internal reflection surfaces, which allows an easy way to illuminate the reticle (from the back side of the prism) even when active illumination is turned off. Being optical telescopes , prism sights can focally compensate for a user's astigmatism . Prismatic sights are lighter and more compact than conventional telescopic sights, but are mostly fixed-powered in
Designated marksman rifle - Misplaced Pages Continue
6258-465: Is known as the mil-hash reticle . Such graduated reticles, along with those with MOA -based increments, are collectively and unofficially called " milling reticles ", and have gained significant acceptance in NATO and other military and law enforcement organizations. Mil-based reticles, being decimal in graduations, are by far more prevalent due to the ease and reliability of ranging calculations with
6407-522: Is often equipped with an unmagnified Aimpoint CompM2 or CompM4 . Commonly, the sighting system will be the only difference between the standard rifle and the designated marksman rifle, as is the case with the F88S DMR issued to the Australian Army. Sniper rifles tend to have even greater magnification than designated marksman rifles, fitting their increased effective range in comparison, as
6556-675: Is that admirable secret, which, as all other things, appeared when it pleased the All Disposer, at whose direction a spider's line drawn in an opened case could first give me by its perfect apparition, when I was with two convexes trying experiments about the sun, the unexpected knowledge...if I .... placed a thread where that glass [the eyepiece] would best discern it, and then joining both glasses, and fitting their distance for any object, I should see this at any part that I did direct it to ..." — William Gascoigne In 1776, Charles Willson Peale collaborated with David Rittenhouse to mount
6705-448: Is that many of the gas piston modifications for the M4 isolate the piston so that piston jams or related malfunction require the entire weapon be disassembled, such disassembly cannot be performed by the end-user and requires a qualified armorer to perform out of field, whereas almost any malfunction with the direct-impingement system can be fixed by the end-user in field. The second is that gas piston alternatives use an off-axis operation of
6854-565: Is the case with the M110 SASS used by the U.S. Army, equipped with a Leupold 3.5-10× variable-power scope. However, some designated marksman rifles, such as the Mk 12 Special Purpose Rifle or the Squad Advanced Marksman Rifle are fitted with scopes with similar magnification. In some cases, the designated marksman rifle will have a longer barrel than the standard issued rifle. For example, until October 2015, when
7003-470: Is the square of the exit pupil as measured in mm; a 36 mm objective lens diameter divided by the 4× magnification gives an exit pupil of 9 mm; 9×9=81) A relatively new type of telescopic sight, called prismatic telescopic sight , prismatic sight or " prism scope ", replaces the image-erecting relay lenses of a traditional telescope with a roof prism design commonly found in compact binoculars , monoculars and spotting scopes . The reticle
7152-463: Is usually provided by a battery -powered LED , though other electric light sources can be used. The light is projected forward through the sight, and reflects off the back surface of the reticle. Red is the most common colour used, as it least impedes the shooter's natural night vision . This illumination method can be used to provide both daytime and low-light conditions reticle illumination. Radioactive isotopes such as tritium can also be used as
7301-506: The Battle of Mogadishu (1993) , in which Rangers complained that their M16 rifles were "unwieldy", whereas members of Delta Force in the same battle, equipped with the CAR-15, had no such complaints. The M4 carbine first saw action in the hands of U.S. troops deployed to Kosovo in 1999 in support of the NATO -led Kosovo Force . It would subsequently be used heavily by U.S. forces during
7450-594: The Cartesian coordinate system , which the shooter can use as a simple reference for rough horizontal and vertical calibrations. Crosshair reticles typically do not have any graduated markings, and thus are unsuitable for stadiametric rangefinding . However some crosshair designs have thickened outer sections that help with aiming in poor contrast situations when the fine crosshair center cannot be seen clearly. These "thin-thick" crosshair reticles, known as duplex reticles , can also be used for some rough estimations if
7599-532: The Colt Advanced Piston Carbine (APC). The weapon has a suppression-ready fluted barrel, which is lighter and cools better than previous M4 barrels. It is claimed to have "markedly better" accuracy. To improve reliability, Colt used an articulating link piston (ALP), which "reduces the inherent stress in the piston stroke by allowing for deflection and thermal expansion". In traditional short-stroke gas piston operating systems designed for
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#17327880272927748-910: The Dragunov sniper rifle (SVD) and similar designated marksman rifles have a barrel of this length. The designated marksman rifles based on the M14 have barrels 460–560 mm (18–22 in) long. In most cases, a designated marksman rifle will share the caliber and possibly even the ammunition type used by standard-issue rifles. DM rifles may be issued with standard ball ammunition , or special match grade loads, such as 7.62 mm NATO 'M118LR' sniper round. Sniper rifles are (almost exclusively) deployed with match grade ammunition in order to take advantage of their full effective range and accuracy potential; in addition, some sniper rifles are chambered for specialized ammunition, such as .338 Lapua Magnum or .338 Norma Magnum , that they do not share with common weapons. In
7897-665: The FN SCAR , but later withdrew their purchase, as it was not a significant enough improvement over the M4A1. The U.S. Army briefly had a tender in 2011 called the Individual Carbine , which solicited proposals for a potential M4 carbine replacement, but this was canceled in 2013 after determining that none of the entrants offered an adequate improvement over the M4. For the Individual Carbine competition, Colt submitted their Enhanced M4 design, also known as
8046-645: The M4 carbine was approved as the new standard-issue rifle, the M16A4 rifle was still standard issue throughout the United States Marine Corps. The barrel on the Mk 12 Special Purpose Rifle , the current rifle used by the squad designated marksman in the USMC, is only 500 mm (18 in) long - 50 mm (2 in) shorter than the barrel on the standard rifle. This is no longer the case, however, as
8195-584: The Magpul Industries M-LOK rail interface system. The URG-I also replaces the Block II's heavier barrel with a standard "government profile" cold hammer forged barrel with a longer gas system. The initial order of M4 carbines had a fixed carrying handle and rear sight similar to the M16A2. The flattop upper receiver with the Picatinny rail was introduced with the M4A1 variant in 1994, and all subsequent orders for all M4 variants would have
8344-822: The Masterkey and M26-MASS shotguns . In April 2022, the U.S. Army selected the XM7 rifle , a variant of SIG MCX Spear , as the winner of the Next Generation Squad Weapon Program to replace the M16/M4. Following the military adoption of the Armalite AR-15 as the M16 rifle , carbine variants were also adopted for CQC operations, the first of which was the CAR-15 family of weapons, which
8493-495: The StG 44 assault rifle, intended primarily for night use. The issuing of the ZG 1229 Vampir system to the military started in 1944 and it was used on a small scale in combat from February 1945 until the final stages of World War II. Telescopic sights are classified in terms of the optical magnification (i.e. "power") and the objective lens diameter . For example, "10×50" would denote
8642-519: The eyepiece , since the image illuminance is often sufficient without needing an enlarged objective bell to enhance light-gathering. Most LPVOs have reticles mounted at the second focal plane, but recently first-focal plane LPVOs have become popular, especially those with high zoom ratios above 6×. LPVOs are also informally referred to as " AR scopes" or " carbine scopes", due to the recently increasing popularity of modern sporting rifles and compact "tactical"-style semi-automatic rifles used among
8791-707: The free-floated Daniel Defense Rail Interface System II (RIS II), first issued in 2008. The RIS II is available in 9.5 inches for the Mk 18 Mod 1 or 12.5 inches for the M4A1. Other components of the Block II include the L3 Advanced Target Pointer Illuminator Aiming Laser (ATPIAL), or the AN/PEQ-15 as well as the LA5 high-power variants, and the ELCAN SpecterDR 1-4 optic. The Upper Receiver Group-Improved (URG-I)
8940-501: The law enforcement , home defense and practical shooting enthusiasts crowd. Telescopic sights are usually designed for the specific application for which they are intended. Those different designs create certain optical parameters. Those parameters are: Because a typical telescopic sight has several optical elements with special characteristics and several air-to-glass surfaces, telescopic sight manufacturers use different types of optical coatings for technical reasons and to improve
9089-624: The war on terror , including in Operation Enduring Freedom and the Iraq War . In the Army, the M4 had largely replaced M16A2s as the primary weapon of forward deployed personnel by 2005. The M4 carbine also replaced most submachine guns and selected handguns in U.S. military service, as it fires more effective rifle ammunition that offers superior stopping power and is better able to penetrate modern body armor . In 2007,
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#17327880272929238-612: The 1990s, the Objective Individual Combat Weapon competition was put forth to find a replacement for the M4. Two designs were produced, both by Heckler & Koch : the XM29 OICW , which incorporated a smart grenade launcher, but was canceled in 2004 as it was too heavy, and the XM8 , which was canceled in 2005 as it did not offer significant enough improvements over the M4. The Heckler & Koch HK416
9387-483: The 60,000 total rounds firing without a problem. The Army said it planned to improve the M4 with a new cold-hammer-forged barrel to give longer life and more reliable magazines to reduce the stoppages. Magazine failures caused 239 of the M4's failures. Army officials said the new magazines could be combat-ready by spring if testing went well. The Army began issuing an improved STANAG magazine in March 2009. According to
9536-463: The AR platform, the force of the piston striking the bolt carrier can push the bolt carrier downwards and into the wall of the buffer tube, leading to accelerated wear and even chipped metal. This is known as carrier tilt . The ALP allows the operating rod to wiggle to correct for the downward pressure on the bolt and transfers the force straight backwards in line with the bore and buffer assembly, eliminating
9685-492: The Army had done. This is because of the carbine's lighter weight, compact length, and ability to address modern combat situations that happen mostly within close quarters; if a squad needs to engage at longer ranges, the M27 Infantry Automatic Rifle can be used as a designated marksman rifle . Approval of the change would move the M16 to support personnel, while armories already had the 17,000 M4s in
9834-449: The Army, the M4 only suffered 296 stoppages and said that the high number reported could be attributed to discrepancies in the scoring process. The Army testing command stated that, if the number of stoppages caused by a broken part met some threshold, they would be eliminated from the final report pending redesign of the part. The methodology of the test has been debated, as many of the M4s in
9983-711: The British Special Air Service uses a variant on the basic theme, the Colt Canada C8SFW . Colt Model 925 carbines were tested and fitted with the KAC M4 RAS under the designation M4E2 , but this designation appears to have been scrapped in favor of mounting this system to existing carbines without changing the designation. The U.S. Army Field Manual specifies for the Army that adding the Rail Adapter System (RAS) turns
10132-399: The CQBR, the SPR would eventually be issued as a standalone complete rifle designated the Mk. 12 Special Purpose Rifle , with some assembled from M4A1 lower receivers. The SOPMOD Block II is a more radical modification kit for the baseline M4A1 that can be fitted at first-echelon unit maintenance level. Components of the Block II were phased in gradually, but the most distinctive feature is
10281-586: The Colt M5), and the XM250 Squad Automatic Weapon. Operational testing and fielding are scheduled for 2024. The M4, and its variants, is a lightweight 5.56×45mm NATO (and .223 Remington ) caliber, gas-operated, magazine-fed, air-cooled selective fire AR-15-pattern firearm . Its gas operation consists of an internal piston (often incorrectly referred to as direct impingement ), a rotating bolt, and bolt carrier that reciprocates into
10430-454: The DM's platoon . They typically have telescopic sights for more detailed observation and aiming, often also quick-deployed bipod for optimized accuracy , reduced recoil and better stability, and an adjustable stock for better ergonomics . Most designated marksman rifles are based on modified designs of an assault rifle currently issued by a nation's military, or on a battle rifle that
10579-761: The Heckler & Koch HK416. Ten of each type of rifle were used to fire 6,000 rounds each, for a total of 60,000 rounds per rifle type. The M4 suffered far more stoppages than its competitors: 882 stoppages, 19 requiring an armorer to fix. The XM8 had the fewest stoppages, 116 minor stoppages and 11 major ones, followed by the FN SCAR with 226 stoppages and the HK416 with 233. Despite 863 minor stoppages—termed "class one" stoppages, which require 10 seconds or less to clear, or "class two" stoppages, which require more than ten seconds to clear—the M4 functioned well, with over 98% of
10728-521: The M16, the M4 accepts a blank-firing attachment (BFA) for training purposes. The M4 and the M4A1 feed from 30-round STANAG magazines . Other types of STANAG compatible magazines with different capacities may also be used. In January 2017, a USMC unit deployed with suppressors mounted to every infantry M4 service weapon. Exercises showed that having all weapons suppressed improved squad communication and surprise during engagements; disadvantages included additional heat and weight, increased maintenance, and
10877-462: The M16A2 in the Army and Marines. The U.S. Air Force , for example, has transitioned completely to the M4 for Security Forces squadrons, while other armed personnel retain the M16A2. The U.S. Navy uses M4A1s for Special Operations and vehicle crews. However, the M4's shorter barrel reduces its range, with its rear iron sights integrated in the (removable) carry handle only adjustable from 300 m (328 yd) up to 600 m (656 yd), compared to
11026-423: The M16A2 rear iron sights integrated in the fixed carry handle, which can reach up to 800 m (875 yd). Like all the variants of the M16, the M4 and the M4A1 can be fitted with many accessories, such as slings , night-vision devices , flash suppressors , suppressors , laser sights , telescopic sights , bipods , M9 bayonet , either M203 or M320 grenade launcher, M26-MASS shotgun, forward hand grips ,
11175-571: The M16A2 rifle, as well as lengthening the barrel to 14.5 inches (370 mm). In January 1984, the U.S. Army revised the QRP, and a month later, it formally approved development of the new carbine. In June 1985, the Picatinny Arsenal was given a contract to produce 40 prototypes of the XM4. Initially a joint program between the Army and Marines, in 1986 the Army withdrew their funding. The XM4
11324-516: The M27, while the M4 would be retained for leadership billets at the platoon level and above. MARSOC also retains the M4, as its shorter barrel is more suited to how they operate in confined spaces. In 2009, the U.S. Army took complete ownership of the M4 design. This allowed companies other than Colt to compete with their own M4 designs. The Army planned on fielding the last of its M4 requirement in 2010. In October 2009, Army weapons officials proposed
11473-566: The M4 carbine has a barrel length of only 370 mm (14.5 in). Also, some rifles, such as the F88S Austeyr , have a barrel that is the same length as the standard service rifle. The FD-200 has an accurized barrel, also found on designated marksman rifles. Most sniper rifles, such as the Accuracy International Arctic Warfare , have a barrel with a length of 610 mm (24 in) or greater. Only
11622-467: The M4 has a "S-1-3" (safe/semi-automatic/3-round burst) trigger group. The M4A1 is used by almost all U.S. special operation units; and is the standard service rifle across the U.S. Army (including conventional forces). It has a maximum effective range of 500 to 600 meters (550–660 yd). The fully automatic trigger gives a more consistent trigger pull, which leads to better accuracy. According to Mark Westrom, owner of ArmaLite, Inc. , automatic fire
11771-479: The M4 have mostly focused on two factors: improving its reliability, and its penetration. The first attempt to find a replacement for the M4 came in 1986, with the Advanced Combat Rifle program, in which the caseless Heckler & Koch G11 and various flechette rifles were tested, but this was quickly dropped as these designs were mostly prototypes, which demonstrated a lack of reliability. In
11920-467: The M4, he illustrates the deficiencies found in the rifle in its current configuration. In the video, he demonstrates his "ArmWest, LLC modified M4", with enhancements he believes necessary to rectify the issues with the weapon. Proprietary issues aside, the weapon is said to borrow features in his prior development, the Ultimax . Sullivan has stated (without exact details as to how) the weapon can fire from
12069-628: The M4. Some issues from this report have been addressed with the issuing of the improved STANAG magazine in March 2009, and the M855A1 Enhanced Performance Round in June 2010. In summer and fall 2007, the Army tested the M4 against three other carbines in " sandstorm conditions" at Aberdeen Proving Ground , Maryland : the Heckler & Koch XM8 , Fabrique Nationale de Herstal SOF Combat Assault Rifle (SCAR) and
12218-430: The M4. The claimed benefits include less needed lubrication for the bolt carrier group to run reliably and reduced fouling. The argument against it is increased weight and reduced accuracy. The Enhanced M4 uses an articulating link piston operating system. Complicating the Army search for higher reliability in the M4 is a number of observations of M4 gas piston alternatives that suffer unintended design problems. The first
12367-543: The M9. While ordinary riflemen in the Marine Corps were armed with M16A4s, M4s were fielded by troops in positions where a full-length rifle would be too bulky, including vehicle operators, fireteam and squad leaders. As of 2013, the U.S. Marine Corps had 80,000 M4 carbines in their inventory. By July 2015, major Marine Corps commands were endorsing switching to the M4 over the M16A4 as the standard infantry rifle, just as
12516-554: The Marine Corps would largely abstain from the effort. Conversion of M4s to the M4A1 in the Army began in 2011, as part of the Product Improvement Program, which included the conversion of 300,000 M4 carbines to the M4A1. The 101st Airborne Division began fielding newly built M4A1s in 2012, and the U.S. 1st Infantry Division became the first unit to convert their M4s to M4A1-standard in May 2014. Upgrades included
12665-635: The Special Operations Peculiar Modification ( SOPMOD ) Block I kit for the carbines used by US Special Operations Forces units operating under its command. The kit features an M4A1, a Rail Interface System (RIS) handguard developed by Knight's Armament Company (KAC), a shortened quick-detachable M203 grenade launcher and leaf sight , a KAC sound suppressor , a KAC back-up rear sight, an Insight Technologies AN/PEQ-2 A visible laser/ infrared designator , along with Trijicon's ACOG TA-01NSN model and Reflex sights , and
12814-617: The U.S. military, designated marksman rifles chambered for 5.56 mm NATO have available the 5 g (77 grain) match grade Mk 262 Mod 0/1 cartridge that enhances the effective range to roughly 600–800 m (2,000–2,600 ft). The effective range of semi-automatic rifles chambered in .338 Lapua Magnum or .338 Norma Magnum can exceed 1,400 m (4,600 ft). All designated marksman rifles in use today are semi-automatic , some with select fire. Sniper rifles are generally bolt-action rifles, but can also be semi-automatic. Telescopic sight A telescopic sight , commonly called
12963-468: The USMC ordered its officers (up to the rank of lieutenant colonel ) and staff non-commissioned officers to carry the M4 carbine instead of the M9 handgun. This is in keeping with the Marine Corps doctrine, "Every Marine a rifleman ." The Marine Corps, however, chose the full-sized M16A4 over the M4 as its standard infantry rifle. United States Navy corpsmen E5 and below are also issued M4s instead of
13112-435: The addition of enhanced components and thus making the platform readily upgradable. The flattop upper receiver's Picatinny rail enables the replacement of the removable carrying handle with various optics. The furniture, including the buttstock, grip, and handguard are made of reinforced plastic, although the modular nature of the weapon means that these can be swapped by the end user. The receiver extension can accommodate either
13261-437: The aim high and away from the target, are therefore called holdover reticles . Such aiming technique can quickly correct for ballistic deviations without needing to manually readjust the sight's zero, thus enabling the shooter to place rapid, reliably calibrated follow-up shots. When shooting at extended distances , the farther the target, the greater the bullet drops and wind drifts that need to be compensated. Because of this,
13410-412: The amount of "lost" light present inside the telescopic sight which would otherwise make the image appear hazy (low contrast). A telescopic sight with good optical coatings may yield a brighter image than uncoated telescopic sights with a larger objective lens, on account of superior light transmission through the assembly. The first transparent interference-based coating Transparentbelag (T) used by Zeiss
13559-451: The amount of space within which the relay lens group and other optical elements can be mounted, the maximum size of the erector tube, and the maximum angular ranges for elevation and windage adjustments. Telescopic sights intended for long-range and/or low-light usage generally feature larger main tube diameters. Besides optical, spatial and attainable range of elevation and windage adjustments considerations, larger diameter main tubes offer
13708-448: The area between the receiver and front sight. Despite the different barrel profile, this subvariant did not receive a new designation, and was still referred to as the M4A1. Ironically, SOCOM itself would dispense with its namesake heavier barrel and return to the original "government profile" with its Upper Receiver Group-Improved (URG-I) program's mid-length gassed, cold hammer forged barrels. The Close Quarters Battle Receiver (CQBR)
13857-532: The available magnification range on FFP sights compared to SFP, and FFP sights are much more expensive compared to SFP models of similar quality. Most high-end optics manufacturers leave the choice between a FFP or SFP mounted reticle to the customer or have sight product models with both setups. Variable-power telescopic sights with FFP reticles have no problems with point of impact shifts. Variable-power telescopic sights with SFP reticles can have slight point-of-impact shifts through their magnification range, caused by
14006-453: The average male torso is 18–19 in (460–480 mm) wide, author Chris McNab concluded that this meant the M4 can be consistently accurate up to 300 yards, and noted that the frequent usage of optical attachments meant it could be accurate to higher ranges. In 2014, American firearms designer Jim Sullivan provided a video interview regarding his contributions to the M16 and M4 family of rifles while working for Armalite. A noted critic of
14155-452: The baseline model and the fully automatic for the M4A1. Some M4A1 may also have a heavier profile barrel initially developed for SOCOM for prolonged automatic fire; models with this heavier "SOCOM profile" barrel use the same M4A1 designation, and existing weapons can swap to the heavier profile barrel at the unit armory level. Despite being its namesake, SOCOM itself has reverted to the original lighter "government profile" barrel while adopting
14304-423: The best available operating system in the U.S. Army's improved M4A1. In September 2010, the Army announced it would buy 12,000 M4A1s from Colt Firearms by the end of 2010, and would order 25,000 more M4A1s by early 2011. Additionally, the service branch planned to buy 12,000 M4A1 conversion kits in early 2011 and bought 65,000 more later that year. Eventually, the Army would upgrade all of its M4s to M4A1s, although
14453-437: The bottom two quadrants , consisting of elaborate arrays of neatly spaced fine dots, "+" marks or hashed lines (usually at 0.2 mil or ½ MOA intervals), to provide accurate references for compensating bullet drops and wind drifts by simply aiming above (i.e. "hold [the aim] over" the target) and upwind of the target (i.e. deflection shooting , or " Kentucky windage "). This type of reticles, designed to hold
14602-678: The carrier tilt. This relieves stress on parts and helps to increase accuracy. The Individual Carbine competition was canceled before a winning weapon was chosen. After the failure of the Individual Carbine program, the Next Generation Squad Weapon (NGSW) was started in 2017. The program aimed to replace the M4 Carbine and the M249 SAW with weapons that would compensate for their perceived deficiencies when fighting at longer ranges, as well as addressing concerns about
14751-505: The closed bolt in semi-automatic and switch to open bolt when firing in fully automatic, improving accuracy. The weight of the cyclic components of the gun has been doubled (while retaining the weapon's weight at less than 8 pounds). Compared to the standard M4, which in automatic fires 700–950 rounds a minute, the rate of fire of the ArmWest, LLC M4 is heavily reduced both to save ammunition and reduce barrel wear. The reduced rate also renders
14900-475: The coating, the character of the image seen in the telescopic sight under normal daylight can either "warmer" or "colder" and appear either with higher or lower contrast. Subject to the application, the coating is also optimized for maximum color fidelity through the visible spectrum . A common application technique is physical vapor deposition of one or more superimposed very thin anti-reflective coating layer(s) which includes evaporative deposition , making it
15049-414: The commercial and military and law enforcement sights. Older telescopic sights often did not offer internal windage and/or elevation adjustments in the telescopic sight. In case the telescopic sight lacked internal adjustment mechanisms adjustable mounts are used (on the scope rings or the mounting rail itself) for sighting-in . Telescopic sights come with a variety of different reticles , ranging from
15198-472: The current M4A1 version can fire 1,691 mean rounds between stoppages using M855A1 ammunition. During the 2009 Marine Corps Infantry Automatic Rifle testing, the Colt IAR displayed a MRBS of CLASS I/II Stoppages of 952 rounds, with a MRBEFF (Mean Rounds Between Essential Function Failure) of Class III Stoppages of 60,000 rounds. An array of firearms accessory makers have offered gas piston conversion kits for
15347-502: The defining firearms of the 21st century". Since its adoption in 1994, the M4 has undergone over 90 modifications to improve the weapon's adaptability , ergonomics and modularity , including: the M4A1, which strengthened the barrel and replaced the burst-fire option with a fully automatic option; the SOPMOD , an accessory kit containing optical attachments; and the underbarrel weapons such as M203 and M320 grenade launchers to
15496-544: The designated marksman from the ground up. Examples include the Soviet SVD and Chinese QBU-88 . Some designated marksman rifles will have some type of optical sight with a higher magnification level than the standard-issue rifle. For example, the Squad Designated Marksman Rifle issued to U.S. Army marksmen is frequently fitted with a Trijicon 4× ACOG , while the standard-issue M4 carbine
15645-410: The effectiveness of traditional 5.56x45mm ammunition against troops wearing body armor in a future peer or near-peer conflict. In order to achieve these goals, all weapon submissions were to be chambered in a new 6.8x51 mm caliber. SIG Sauer, Textron Systems, FN Herstal, True Velocity (previously Lonestar Future Weapons and General Dynamics), and PCP Tactical took part in the program. Textron submitted
15794-513: The firearm and operational requirements) to allow rapid engagement of multiple targets. DMRs have to be effective, in terms of hit rates and terminal ballistics , at application ranges exceeding those of ordinary assault rifles and battle rifles , but do not require the extended-range performance of a dedicated sniper rifle. DMRs need to function as part of squad (and possibly at close quarters) and often share some basic characteristics with sniper rifles when compared to other weapons carried in
15943-563: The firearm to become proprietary to the manufacturer, making modifications and changes with parts from other manufacturers difficult. In a study conducted by the Army Marksmanship Unit , they found that at a distance of 300 yd (270 m), the M16 achieved a 24 in (610 mm) grouping , and the M4 achieved a 32 in (810 mm) grouping, which dropped to 12 in (300 mm) and 18 in (460 mm) respectively when using match grade ammunition. As
16092-446: The front post on iron sights . However, most reticles have both horizontal and vertical lines to provide better visual references. The crosshair is the most rudimentary reticle, represented as a pair of smooth, perpendicularly intersecting lines in the shape of a " + ", and the crosshair center is used for aiming the weapon. The crosshair lines geometrically resemble the X- and Y-axis of
16241-460: The greater cost of equipping so many troops with the attachment. In July 2020, the Marine Corps announced it would be ordering suppressors for use by all M4 carbines used by close combat units. The Marines began to roll out suppressors for all M4/M4A1 carbines in infantry, reconnaissance and special operations units in December 2020. In 1992, U.S. Special Operations Command (USSOCOM) developed
16390-410: The heavier SOCOM barrel to better dissipate heat from sustained automatic firing, the full-auto trigger group with a more consistent trigger pull than the burst group's to enable better semi-automatic accuracy, and the ambidextrous selector lever for easier use with left-handed shooters. The M4-M4A1 conversion increases weapon weight from 7.46 lb (3.38 kg) to 7.74 lb (3.51 kg), counting
16539-418: The highest power. Some long-range shooters and military snipers use fixed-power telescopic sights to eliminate this potential for error. Some SFP sights take advantage of this aspect by having the shooter adjust magnification until the target fits a certain way inside the reticle and then extrapolate the range based on the power adjustment. Some Leupold hunting sights with duplex reticles allow range estimation to
16688-604: The human eye luminous efficiency function variance. Maximal light transmission around wavelengths of 555 nm ( green ) is important for obtaining optimal photopic vision using the eye cone cells for observation in well-lit conditions. Maximal light transmission around wavelengths of 498 nm ( cyan ) is important for obtaining optimal scotopic vision using the eye rod cells for observation in low light conditions. These allow high-quality 21st century telescopic sights to practically achieve measured over 90% light transmission values in low light conditions. Depending on
16837-402: The image they produce. Lens coatings can increase light transmission, minimize reflections, repel water and grease and even protect the lens from scratches. Manufacturers often have their own designations for their lens coatings. Anti-reflective coatings reduce light lost at every optical surface through reflection at each surface. Reducing reflection via anti-reflective coatings also reduces
16986-407: The inventory needed to outfit all infantrymen who needed one. In October 2015, Commandant Robert Neller formally approved of making the M4 carbine the primary weapon for all infantry battalions, security forces, and supporting schools in the USMC. The switch was to be completed by September 2016. In December 2017, the Marine Corps revealed a decision to equip every Marine in an infantry squad with
17135-434: The late 1630s, English amateur astronomer William Gascoigne was experimenting with a Keplerian telescope and left it with the case open. Later he found that a spider had spun its web inside the case, and when he looked through the telescope he found that the web was in focus with distant objects. Gascoigne realised that he could use this principle to make a telescopic sight for use in his astronomical observations. "This
17284-432: The low magnification range (1–4×, 1–6×, 1–8×, or even 1–10×) are known as low-power variable optics or LPVOs . These telescopic sights are often equipped with built-in reticle illumination and can be dialed down to 1× magnification. As low magnifications are mostly used in close- and medium ranges, LPVOs typically have no parallax compensation (though a few rare models do) and have a completely cylindrical shape ahead of
17433-614: The low magnification ranges (usually 2×, 2.5×, 3× or more commonly 4×, occasionally 1× or 5× or more), suitable for shooting at short/medium distances. One of the best known examples is the battle-proven Trijicon ACOG used by the USMC , US Army, and USSOCOM , although variable-magnification prism sights do also exist, such as the ELCAN Specter DR/TR series used by the Canadian Army . Variable-zoom telescopic sights in
17582-645: The modularity of the AR-15/M4 platform, some operators have replaced issued optics, handguards, and buttstocks with aftermarket ones. In 2018, the Upper Receiver Group-Improved (URG-I) modification kit (unofficially the Block III) was approved for the conversion of Block I and Block II carbine's upper receiver "to an improved barrel and rail assembly.." which includes a lighter free-float handguard from Geissele Automatics that incorporates
17731-498: The older M193 cartridges. In 1983, the 9th Infantry Division requested a Quick Reaction Program (QRP) for a 5.56mm carbine to replace the M1 carbine and M3 submachine gun in service. The XM4 was tested by the Army's Armament Research and Development Center (ARDC) in June 1983. Later, the gun was updated with improved furniture, and a barrel with rifling of 1 turn in 7 inches (180 mm). The ARDC recommended additional commonality with
17880-547: The oldest type of reticles and are made out of metal wire or thread, mounted in an optically appropriate position in the telescopic sight's tube. Etched reticles are an optic element, often a glass plate, with inked patterns etched onto it, and are mounted as an integrated part of the lightpath . When backlit through the ocular, a wire reticle will reflect incoming light and cannot present a fully opaque (black) reticle with high contrast. An etched reticle will stay fully opaque (black) if backlit. Reticle patterns can be as simple as
18029-468: The optical needs of European hunters who live in jurisdictions that allow hunting at dusk, night and dawn differ from hunters who traditionally or by legislation do not hunt in low light conditions. The main disadvantage of SFP designs comes with the use of range-finding reticles such as mil-dot. Since the proportion between the reticle and the target is dependent on selected magnification, such reticles only work properly at one magnification level, typically
18178-460: The original M4 to the new M4A1 version. The first 24,000 were to be made by Remington Arms Company . Remington was to produce the M4A1s from mid-2013 to mid-2014. After completion of that contract, it was to be between Colt and Remington to produce over 100,000 more M4A1s for the U.S. Army. Because of efforts from Colt to sue the Army to force them not to use Remington to produce M4s, the Army reworked
18327-418: The original solicitation for new M4A1s to avoid legal issues from Colt. On 16 November 2012, Colt's protest of Remington receiving the M4A1 production contract was dismissed. Instead of the contract being re-awarded to Remington, the Army awarded the contract for 120,000 M4A1 carbines worth $ 77 million to FN Herstal on 22 February 2013. The order was expected to be completed by 2018. Replacements for
18476-430: The piston that can introduce carrier tilt, whereby the bolt carrier fails to enter the buffer tube at a straight angle, resulting in part wearing. This can also tilt the bolt during extraction, leading to increased bolt lug failures. The third is that the use of a sound suppressor results in hot gases entering the chamber, regardless of a direct-gas impingement or gas piston design choice. The gas piston system may also cause
18625-912: The positioning of the reticle in the mechanical zoom mechanism in the rear part of the telescopic sight. Normally these impact shifts are insignificant, but accuracy-oriented users, who wish to use their telescopic sight trouble-free at several magnification levels, often opt for FFP reticles. Around the year 2005 Zeiss was the first high-end European telescopic sight manufacturer who brought out variable magnification military grade telescopic sight models with rear SFP mounted reticles. They get around impermissible impact shifts by laboriously hand-adjusting every military grade telescopic sight. The American high-end telescopic sight manufacturer U.S. Optics Inc. also offers variable magnification military grade telescopic sight models with SFP mounted reticles. Either type of reticle can be illuminated for use in low-light or daytime conditions. With any illuminated low-light reticle, it
18774-709: The possibility to increase the tube walls thickness (hence a more robust sight) without sacrificing a lot of internal diameter. A telescopic sight can have several manual adjustment controls in the form of control knobs or coaxial rings. All telescopic sights have the first three (diopter, elevation, windage) adjustment controls, and the fourth (magnification) control is offered on variable-power sights. The remaining two adjustments are optional and typically only found on higher-end models with additional features. The windage and elevation adjustment knobs (colloquially called "tracking turrets") often have internal ball detents to help accurately index their rotation, which provide
18923-528: The reference arrays of holdover reticles are typically much wider at the lower portion, shaping into an isosceles triangle / trapezium that resembles the canopy of a spruce , the ornamental tree traditionally used to make Christmas trees . Holdover reticles therefore are colloquially also known as " Christmas tree reticles ". Well-known examples of these reticles include GAP G2DMR, Horus TReMoR series and H58/H59, Vortex EBR-2B and Kahles AMR. Telescopic sights based on image erector lenses (used to present to
19072-554: The reliability of their M4 carbines, as well as the M16 rifle. Troops did not report reliability problems with their rifles. While only 100 troops were asked, they fought at least a dozen intense engagements in Helmand Province , where the ground is covered in fine powdered sand (called "moon dust" by troops) that can stick to firearms. Weapons were often dusty, wet, and covered in mud. Intense firefights lasted hours with several magazines being expended. Only one soldier reported
19221-468: The same designation as the Air Force CAR-15 variant in service since 1966. The M4 carbine has been used for close quarters operations where the M16 would be too long and bulky to use effectively. It has been a compact, light, customizable, and accurate weapon. Like other firearms, failure to properly maintain the M4 can result in malfunctions. This became apparent as it saw continued use in
19370-617: The sandy environments of Iraq and Afghanistan . Despite this, in post-combat surveys, 94% of soldiers rated the M4 as an effective weapons system. In December 2006, the Center for Naval Analyses (CNA) released a report on U.S. small arms in combat. The CNA conducted surveys on 2,608 troops returning from combat in Iraq and Afghanistan over the previous 12 months. Only troops who fired their weapons at enemy targets were allowed to participate. 917 troops were armed with M4 Carbines, making up 35% of
19519-409: The simple crosshairs to complex reticles designed to allow the shooter to range a target, to compensate for the bullet drop, and to adjust windage required due to crosswinds. A user can estimate the range to objects of known size, the size of objects at known distances, and even roughly compensate for both bullet drop and wind drifts at known ranges with a reticle-equipped sight. For example, with
19668-657: The standard sharpshooter equipment during the American Civil War . Other telescopic sights of the same period were the Davidson and the Parker Hale . An early practical refracting telescope based telescopic sight was built in 1880 by August Fiedler (of Stronsdorf , Austria ), forestry commissioner of German Prince Reuss . Later telescopic sights with extra long eye relief became available for use on handguns and scout rifles . A historic example of
19817-474: The standard "government profile" barrel in its subsequent M4 improvement programs. The benefits of these changes, however, have come under scrutiny from both the military and civilian firearms community. According to a PDF detailing the M4 Carbine improvement plans released by PEO Soldier, the direct impingement system would be replaced only after reviews were done comparing the direct impingement system to commercial gas piston operating system to find out and use
19966-901: The stoppage and re-engage their target. The lowest rated weapon was the M9, and the M249 had the highest rate of stoppages. 53% of the M4 users never experienced failures of their magazines to feed. 81% did not need their rifles repaired while in theater. 80% were confident in the M4's reliability, defined as confidence their weapon will fire without malfunction, and 83% were confident in its durability, defined as confidence their weapon will not break or need repair. Both factors were attributed to high levels of soldiers performing their own maintenance. 54% of M4 users offered recommendations for improvements. 20% of requests were for greater bullet lethality, and 10% were for better quality magazines, as well as other minor recommendations. Only 75% of M16 users were satisfied with it, and some expressed their desire to be issued
20115-438: The survey. 89% of M4 users reported they were satisfied with the weapon. 90% were satisfied with handling qualities such as handguards, size, and weight. M4 users had the highest levels of satisfaction with weapon performance, including 94% with accuracy, 92% with range, and 93% with rate of fire. Only 19% of M4 users reported a stoppage, and 82% of those that experienced a stoppage said it had little impact on their ability to clear
20264-499: The test had already seen use, whereas the other rifles were brand new, and that the wide variance in results between summer and fall showed that the test was not accurate, as it was not repeatable with consistent results. Furthermore, the trial M4s had burst-mode fire groups, which are more complicated and prone to failure than the fully automatic fire groups the other manufacturers presented for testing. There were three extreme dust tests performed in 2007. The second test results showed
20413-841: The time, the Colt M16A2 was the Colt 645, also known as the M16A1E1. Later that year, the U.S. Army Armament Munitions Chemical Command helped Colt develop a new variant of the XM177E2, and the U.S. Army redesignated the XM177E2 to the XM4 Carbine, giving the name as the successor to the M3 carbine . The carbine used the same upper and lower receiver as the M16A1, and fires the M855 cartridge along with
20562-462: The transition point between thinner and thicker lines are at a defined distance from the center, as seen in designs such as the common 30/30 reticles (both the fine horizontal and vertical crosshair lines are 30 MOAs in length at 4× magnification before transition to thicker lines). There can be additional features such as enlarged center dot (frequently also illuminated ), concentric circle (solid or broken/dashed), chevron , stadia bars, or
20711-812: The ubiquitous metric units , as each milliradian at each meter of distance simply corresponds to a subtension of 1 millimeter; while MOA-based reticles are more popular in civilian usage favoring imperial units (e.g. in the United States), because by coincidence 1 MOA at 100 yards (the most common sight-in distance) can be confidently rounded to 1 inch. To allow methodological uniformity, accurate mental calculation and efficient communication between spotters and shooters in sniper teams , mil-based sights are typically matched by elevation/windage adjustments in 0.1 mil increments. There are however military and shooting sport sights that use coarser or finer reticle increments. By means of
20860-551: The user with an upright image) have two planes of focus where a reticle can be placed: at the focal plane between the objective and the image erector lens system (the First Focal Plane (FFP)), or the focal plane between the image erector lens system and the eyepiece (the Second Focal Plane (SFP)). On fixed power telescopic sights there is no significant difference, but on variable power telescopic sights
21009-488: The weapon into the M4 MWS or modular weapon system . The M4A1 carbine is a fully automatic variant of the basic M4 carbine. The M4A1 was developed in May 1991 and entered service in 1994; starting in 2014 the U.S. Army began upgrading all of its existing M4s to the M4A1 standard. The M4A1 was the first M4 model with the removable carry handle. The M4A1 has a "S-1-F" (safe/semi-automatic/fully automatic) trigger group, while
21158-438: The weapon more controllable and accurate in automatic firing. The M4 was developed and produced for the United States government by Colt Firearms, which had an exclusive contract to produce the M4 family of weapons through 2011. However, a number of other manufacturers offer M4-like firearms. Colt previously held a U.S. trademark on the term "M4". Many manufacturers offer production firearms that are essentially identical to
21307-447: The wind speed, from observing flags or other objects, by a trained user through using the reticle marks. The less-commonly used holdunder, used for shooting on sloping terrain, can even be estimated by an appropriately-skilled user with a reticle-equipped sight, once both the slope of the terrain and the slant range to target are known. There are two main types of reticle constructions: wire reticle and etched reticle . Wire reticles are
21456-516: Was finished in 1987, and the Marines adopted 892 for that fiscal year , with the designation "carbine, 5.56mm, M4". Owing to experience from the 1991 Gulf War , the Army gave Colt its first production contracts for M4 carbines in May and July 1993, and M4A1 carbines for United States Special Operations Command (SOCOM) operators in February 1994. Interest in the M4 carbine was accelerated after
21605-565: Was formerly issued. The ammunitions used are often of the same caliber as that of the machine guns within the same combat unit , typically a fully powered cartridge such as the 7.62 mm NATO . For example, battle rifles such as the M14 , FN FAL , AR-10 and Heckler & Koch G3 were largely replaced during the 1980s and 1990s by modern assault rifles firing the 5.56 mm NATO intermediate cartridge for standard riflemen, but many were accurized and retained as DMRs. Conversely, some nations have also built rifles that were designed for
21754-649: Was introduced in 2005, incorporating the same lower receiver as the M4A1, but replacing its direct impingement system with a gas-operated rotating bolt, more comparable to that of the G36 . The HK416 was adopted by the Navy SEALs , Delta Force , and other special forces. In 2010, it was adopted by the Marines as the M27 Infantry Automatic Rifle. The same year, the Rangers and Navy SEALs adopted
21903-478: Was invented in 1935 by Olexander Smakula . A classic lens-coating material is magnesium fluoride , which reduces reflected light from 5% to 1%. Modern lens coatings consist of complex multi-layers and reflect only 0.25% or less to yield an image with maximum brightness and natural colors. Determined by the optical properties of the lenses used and intended primary use of the telescopic sight, different coatings are preferred, to optimize light transmission dictated by
22052-409: Was originally a Special Operations Peculiar Modification (SOPMOD) program item that would increase the close quarters maneuverability of the M4A1 by mating the lower receiver with a 10.3-inch (262 mm) barreled upper receiver; with the CQBR installed, the weapon would then be classified as the Mk. 18 CQBR . The Mk. 18 CQBR may be issued as a standalone complete weapon system to SOCOM personnel, or as
22201-459: Was used in the Vietnam War . However, these rifles had design issues, as the barrel length was halved to 10 inches (25 cm), which upset the ballistics , reducing its range and accuracy and leading to considerable muzzle flash and blast, meaning that a large flash suppressor had to be fitted. In 1982, the U.S. Government requested Colt to make a carbine version of the M16A2. At
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