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74-793: The SDM-R is similar in development and role to the SEAL Recon Rifle and Mk 12 Special Purpose Rifle (SPR), designed and produced for the United States Navy SEALs and the United States Special Operations Command respectively. The SDM-R was replaced by the M110A1 SDMR , expected to enter service in the 2020s. In this role, the M110A1 retains the "Squad Designated Marksman Rifle" name. The addition of an embedded marksman at

148-422: A Colt Python Target model, with six, five and eight inch long barrels, respectively. Ten groups of five shots were fired and measured from each revolver with each ammunition. Click on the image at right to see a larger view of the graph of average group sizes for each type of ammunition and each revolver. The average group size for the overall test was 72 millimetres (2.85 in). Based on average group size,

222-419: A bolt with an outside diameter (OD) of 0.697 inches which is operating in a receiver with a bolt raceway inside diameter (ID) of 0.702 has a clearance of 0.005 inches. If the bolt OD has a nominal OD of 0.698 and a tolerance of +/- 0.001, then the bolt OD can randomly vary from 0.697 to 0.699 along its length, which will allow the bolt clearance in the 0.702 diameter raceway to vary from 0.005 to 0.003. Further, if

296-402: A commercial barrel liner. If the barrel is unsuitable and relining is not an option, then an aftermarket or custom barrel is the best solution. However, if the bore is good, then there are a number of operations that can be done to the barrel to improve upon its accuracy. Ideally, the bore must be cylindrical and the rifling geometry the same down the length of the bore. Some airgun rifles have

370-431: A firearm, the goal is to produce the most consistent possible results. The shooter must also be consistent, and this means that the fundamentals of marksmanship have to be followed rigorously; any failure on the part of the shooter to remain focused and consistent can result in a bad shot. It's common to use a benchrest or a vise when evaluating ammunition or a weapon for accuracy to eliminate human error. Since adjusting

444-406: A great deal of care and precision, and a bad trigger job can easily render a firearm highly unsafe or unusable. Most manufacturers ship firearms with fairly heavy, nonadjustable triggers, colloquially known as lawyer triggers . This is out of concern for liability; firearms are inherently dangerous, and allowing the user to adjust the trigger, or even implying such adjustments can be made, exposes

518-414: A heavier weight and little or no discernible movement. The overtravel can be the most critical factor in the trigger pull, as any movement caused at this point will happen as the shot is fired. This is especially important with firearms where there is a sudden release of resistance when the sear breaks, such as in double-action triggers. An overtravel stop will arrest the motion of the trigger just after

592-451: A high powered rifle barrel bore in 1.0 to 1.5 milliseconds. Mechanical bolt-action rifle trigger systems with a sub 2.0 millisecond lock time are applied in most purpose designed high end competition rifles. The terms "clearance" and "tolerance" are very often confused and misused. Clearance is the distance between the surfaces of mating parts. Tolerance is the allowable variation of a dimension from its nominal (desired) value. For example,

666-517: A large degree of adjustment, including length of pull , drop, comb height and angle, and buttplate angle and curvature. The bullet does not leave the barrel as soon as the sear releases; rather, there is a delay between the release of the sear and the bullet exiting the barrel. During this time, any movement will move the firearm off target, and so this time should be minimized, especially for firearms that will be fired from an unsupported standing position. This delay can be broken down into two sections,

740-426: A large degree of friction to prevent the shooter's grip from shifting. This can be done by either using a material that provides a high friction, such as rubber , or by adding texture to the grips. Traditionally wood grips and stocks are provided with checkering , a process where V-shaped grooves are cut into the wood at an angle to each other, leaving a pattern of pyramidal projections in the wood. Another process uses

814-421: A maximum point blank range and ideal trigger control. However, these features are not well suited for a typical hunting or action shooting rifle, where the rifle must be brought from a ready position to a shooting position quickly and smoothly. This use favors low sights or scopes, and a shallow pistol grip angle. Rounded forearms are well suited for firing from offhand, while a square-bottomed forearm provides

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888-444: A minute of arc equals 1.047 inches (26.6 mm), and the one MOA group (approximately 1/3 or 0.3 mil) is a traditional benchmark of accuracy. Handguns are generally used at closer ranges, and are tested for accuracy at their intended range of use. Also of importance is the number of shots fired. Statistical likelihood says the fewer shots that are fired, the smaller the dispersion will be. 3 or 5-shot groups are acceptable for zeroing

962-475: A punch to leave a random pattern of dents in the surface, called stippling ; this process is better suited to complex curves than checkering, and is often found on anatomical grips. Handguns with plastic frames will often have stippling or checkering molded into the frame. Grips for handguns, especially ones used in single handed disciplines such as bullseye and Olympic handgun shooting, are critical to good accuracy. The grip provides very little control compared to

1036-405: A rifle stock, and so a good fit is required to give the shooter control over the gun and isolate the trigger finger movement. Aftermarket parts makers provide a wide range of grips for handguns, allowing shooters to find grips that are suitable for their hands. Competition handgun grips are anatomically shaped, and are often custom fitted to the shooter's hand. An ideal grip will fit the contours of

1110-407: A set of real-world conditions. A firearm that is comfortable, fits the user well, and provides for a careful, consistent trigger pull and recoil management is not only a physical advantage over a poorly fit firearm, but a psychological one as well. The dynamics of the trigger are one of the most important aspects of usability, since any movement of the firearm caused by pulling the trigger can affect

1184-506: A short cone towards the muzzle to improve the speed of the bullet. A slight gain in the rifling twist, or a slight tapering down of the bore, will still ensure the tight fit of bullet to bore, so when selecting a barrel, the tighter or faster twist end should be chosen for the muzzle. The twist of the rifling must match the intended ammunition for best accuracy. Rifling with too slow a twist will not stabilize long bullets, causing them to precess in flight; at its worst, this can result in

1258-422: A stable base for shooting off of a sandbag or other rest. Recoil is also a key issue in rifle stock design. Heavy recoiling rifles should have wide butts, with a good recoil pad to absorb the force of recoil, and a comb that is straight or slopes down towards the action, so that it does not push into the shooter's face under recoil. Some target shooting disciplines allow the use of various devices to help support

1332-411: A trigger stop adjustment would limit the overtravel. While adjustable triggers may provide the greatest level of control, much can be done with standard non-adjustable triggers. Careful hand fitting and polishing of parts, addition of high precision or adjustable aftermarket parts, or fabrication of new parts can greatly improve most triggers. Care should be taken, however, since trigger work requires

1406-489: A variety of different loads exist. For example, the M16A1 rifle is unable to accurately fire bullets that are heavier than 3.6 grams (55 gr) due to barrel twist that is too slow to stabilize heavier bullets. Precision rifles typically come with barrels that are either tailor-made for a specific ammunition load or made according to the buyer's specifications. Barrels can also benefit from lapping , not only because it makes

1480-517: A versatile, accurate, lightweight, and relatively compact weapon chambered in 5.56×45mm NATO . The concept of an accurized rifle based on the 5.56 NATO cartridge was first observed in 1993 during the Battle of Mogadishu . This led to the development of various options for improving accuracy in the field, including improved ammunition and triggers, a range of optics, free-floating handguards, and rail systems. Developed in-house by SEAL team armorers,

1554-434: Is also not uncommon for factory crowns to be cut slightly off-center, so that one side of the bullet exits slightly earlier than the other, and this will result in the bullet being pushed away from that side, causing a significant deflection in its path. A crown may be re-cut with relative ease, and this can fix any problems caused by a defective or damaged crown, by ensuring an even release of the bullet. An 11 degree crown has

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1628-491: Is consistency. Getting everything to happen the same way for every shot is key to producing small groupings , and there are a large number of issues to be addressed in achieving an accurate firearm. The keys to firing an accurate shot are a firm but not overtight grip, the ability to get a good sight picture and a controlled squeeze of the trigger. The ability to manage recoil is also important in heavily recoiling calibers, both to aid in possible additional shots, and to prevent

1702-592: Is done in Fort Benning, Georgia. Task Force Small Arms Readiness Group (TF SARG) conducts the week-long SDM course at the SARG academy at Camp Bullis , Texas . Many of the instructors are President's 100 recipients. The 82nd Airborne Division examined an alternate version, based on the M4 carbine . The barrel was to have been an 18-inch (460 mm) long fluted Douglas barrel with 1:8 twist. A mid-length gas system

1776-428: Is often possible to shorten a barrel slightly by removing material from the breech end and re-cut the chamber, which can correct many problems in the original chamber. The crown is the muzzle face of the barrel. The crown's integrity is critical for two reasons: While many barrel manufacturers recess the crown to protect it from accidental damage, it can still be damaged over time by cleaning rods that are too hard. It

1850-415: Is often used to stress-relieve the barrels. The amount of good this does depends on the technique used to make the barrel. For example, the hammer forging method of manufacture leaves a significant amount of stress in the barrels, which could be addressed through stress-relieving heat treatment. Barrel wear is also an important issue, particularly in high-powered firearms. High temperatures tend to erode

1924-418: Is one of the most important factors for accuracy, as a poorly made barrel may be beyond correction. Even a quality barrel must be well matched to the cartridge it will be firing. In most cases, it is not practical to fix a barrel whose bore is worn out, poorly or unsuitably rifled, or the wrong bore diameter; the primary exception to that is rimfire barrels, which can be inexpensively bored out and re-lined with

1998-421: Is the fit of the ammunition to the barrel. The chamber should be concentric, and the throat sized just slightly larger than the bullet diameter. The cartridge must headspace correctly, be held firmly in place, concentric to the bore, and the bullet must fit the bore and be guided to engage the rifling cleanly. Once the bullet is engaged in the rifling, with a good seal and coaxial fit, it must stay that way. It

2072-401: Is the least critical stage of the trigger pull, and individual preferences vary widely. Two-stage triggers, for example, consist of a noticeable takeup, followed by a distinct increase in the force required to pull the trigger, followed by the break. A single-stage trigger, on the other hand, has no discernible movement before the break. Fully adjustable triggers will provide a two-stage pull, and

2146-419: Is the process of improving the accuracy and precision of a gun ( firearm or airgun ). For shooting sport , accuracy is the gun's ability to hit exactly what the shooter is aiming at, and precision is the ability to hit the same place over and over again in a repeatable fashion. Both are the goals of accurizing, which generally concentrates on four different areas: The key to an accurate firearm

2220-415: Is the time between ignition of the cartridge and when the bullet leaves the barrel. Like lock time, dwell time is a window for error, and can be minimized with a faster bullet or a shorter barrel. In some cases, a shorter barrel is desired to reduce dwell time, but without losing the sight radius of a longer barrel. In this case, a sight extension tube, or bloop tube , can be used. This is a tube that fits on

2294-434: Is to measure the edge to edge distance of the farthest holes, and subtract the bullet diameter, which gives the center to center or c-c measurement of the group. This can be expressed in linear measures ( a 30 mm group at 100 m , or a one inch group at 100 yards ) or in angular measures ( a milliradian or MOA group ). Groups for rifles are traditionally shot at either 100 meters or 100 yards (91 m). At 100 yd

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2368-431: The lock time and the bullet dwell time . Lock time is the time between the release of the sear and the ignition of the cartridge, and depends on the design of the firing mechanism. A lengthy lock time gives time for the shooter to drift off target, and so it is advantageous to minimize the lock time and reduce the window for error. Reductions in lock time are generally performed by lightening parts that move as part of

2442-526: The platoon or squad level has historically been a continuing process in the U.S. military . The United States Marine Corps (USMC) experimented with this during Project Metropolis , before creating the "Squad Advanced Marksman" (SAM) role along with the Squad Advanced Marksman Rifle (SAM-R) specifically for this purpose. The 3rd Infantry Division followed suit in implementing a training program to have one marksman per squad,

2516-662: The DMR role. Its slated replacement was the Heckler & Koch HK417 -based M110A1 SDMR , expected to enter service in the early 2020s. The National Guard Marksmanship Training Center of the Arkansas Army National Guard conducts the fourteen-day-long Squad Designated Marksman Course at Camp Joseph T. Robinson . Soldiers fire over 1500-rounds from the M16A4 rifle under the close supervision of course cadre. Another

2590-582: The Squad Designated Marksman (SDM), and developing a rifle, the Squad Designated Marksman Rifle (SDM-R). The SDM is an integral part of the squad and serves as a rifleman first and designated marksman second. The SDM is not meant to be a squad sniper who engages the enemy with precision fire at long ranges, but instead is trained to directly support the squad with well-aimed shots at ranges slightly beyond

2664-419: The ability to reliably shoot on target in changing conditions. Improvements in visibility and sharpness of a target image provided by some sights can also improve users' aim and consistency. Typical open sights with a blade, post or bead near the muzzle and a notch over the breech are good for quick alignment but far from ideal for accuracy. An aperture sight mounted closer to the user's eye and farther from

2738-419: The alterations that can be made. In addition, every firearm is different, and processes that yield good results on one may not affect another. Another issue in measuring accuracy is the method by which the gun is secured for the test. The most accurate shooting position is a supported position, such as firing from a benchrest with the firearm well-supported by a shooting rest or sandbags; this eliminates much of

2812-496: The barrel at the throat, preventing the bullet from entering the rifling cleanly. One way to produce a long-lasting barrel is by the proper selection of materials. Stainless steels , such as 416, have been shown to have a longer life than the traditional 4140 chrome / molybdenum steels used for barrels. While the stainless barrels are not any more accurate than a 4140 barrel, they will maintain their accuracy longer in many applications, as they are more resistant to erosion caused by

2886-454: The best accuracy potential, and should be applied to a barrel to get the best gas flow at the bullet exit point of the barrel. Any machining process on a barrel, whether it's boring, rifling, or turning the outside contour, will produce some stress in the steel of the barrel. This stress can cause the barrel to expand unevenly as it heats, causing shots to "walk" as the barrel heats and cools. To prevent this, careful post-machining heat treatment

2960-419: The bore a more consistent diameter, but also because it polishes the bore. Barrel lapping should be done with the tool moving in the same direction as the bullet will move, so that any imperfections in the barrel will be smoothed out and thus not interfere with the passage of the bullet. A smooth, polished bore will not only hold the bullet better, but also reduce barrel fouling. Of great importance to accuracy

3034-429: The break, and prevent movement. Over travel is not always considered bad by some, as the force of the trigger finger does not impact on the gun directly after sear release. An adjustable trigger may have ways to adjust all of these stages, plus trigger location. For example, a first stage or takeup adjustment might include weight and travel, a second stage or sear engagement adjustment might include weight and travel, and

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3108-433: The bullets tumbling in-flight and keyholing , where bullets strike the target sideways. Too fast a twist can also be a problem, as it can magnify problems in the bullet. A bullet whose center of mass is slightly off-center will diverge at a rate proportional to the rifling twist, so excess twist will result in greater dispersion. In practical terms, this is only a problem for rifles chambered for common military calibers where

3182-514: The firing operation, such as the hammer and firing pin or striker , shortening the distance that parts, moving as components of the firing operation, have to cover, and using a more powerful spring. A short lock time is particularly desired when shooting with high precision at small targets. The lock time of conventional bolt-action rifles typically lie between 2.6 to 9.0 milliseconds. Further reductions in lock time, to near zero levels, can be achieved with electrical primers. The bullet dwell time

3256-440: The fixed stock. Some would go with a Geissele trigger too, and some would put a tube rail back on. All of these little touches were done in house at the shooters home team. Initially, SEAL Recon Rifles were built in-house with the only requirements being a 16" barrel (406mm), and the ability to shoot any 5.56×45mm cartridge in inventory, including the first iterations of the 77-grain (5 gram) Mk262 Mod0 cartridge. Otherwise,

3330-432: The front sight block, and 0.725 inches (18mm) in diameter to the muzzle. These barrels were mated to flat-top upper receivers featuring an M1913 rail, to which optics and back-up iron sights could be attached. Operators commonly chose to install back-up iron sights manufactured by Knight's Armament Company , ARMS Inc, and Troy Industries with the rifles. Recon rifles were reportedly fitted with free-float handguards,

3404-437: The front sight tightens accuracy by lengthening the sight radius while helping the person take better advantage of the improvement. Some of these "peep sights" provide precise, repeatable adjustments for long range shooting with no need for tools. Telescopic and reflex sights offer advantages to people with less experience or poor eyesight by bringing both target and aiming point into focus, while "scopes" also magnify and brighten

3478-426: The handgun should not line up with the forearm when gripped, but rather point slightly outwards, so that when held to shoot, the sights line up with the shooter's eye. In cross-dominant shooters, the angle will be more pronounced. Thumbrests, finger grooves (if well fitted), and palm rests all provide control over recoil. An adjustable palm rest is a desirable feature as well, as it allows the grip to be adjusted to fit

3552-497: The image. Drawbacks such as weight, bulk, and complexity can also affect a shooter's performance. A good stock or grip allows the shooter to have a relaxed but firm grip on the firearm. This can range from minor changes such as texturing grip surfaces or adding a wide, beavertail type grip safety to a 1911, all the way to a custom-built, anatomically designed grip that "fits like a glove". Key features are: Gripping surfaces, particularly on handguns, are often designed to provide

3626-491: The joint program, resulting in the Mk 12 Special Purpose Rifle which many SEALs were disappointed with. Former SEAL sniper Kyle Defoor recounts: It went to 18" quite frankly because the big Army got involved. Most of us that have a lot of time on one (myself included) think that 16" is better for a number of reasons: [...] The MK12 is ok as it comes, but, me and majority of the guys that were around me immediately [replaced]

3700-461: The least sensitivity to differences in ammunition. As the goal of accurizing a firearm is to improve its accuracy, the way accuracy is measured becomes important. A firearm used primarily as a hunting weapon will need to be accurate on the first shot from a cold, clean barrel, while one used for target shooting may be allowed fouling shots before the first shot for record is fired. Issues of portability or restrictions of certain competitions may limit

3774-528: The manufacturer to lawsuit. Likewise, manufacturers of aftermarket parts expose themselves to similar liability issues. A firearm's sights help its user to align the barrel with an intended target. In some cases the only refinement in a "target" firearm over a standard model is improved sights. Adjustable sights are essential for most target shooting, as they allow compensation for variables such as target range and ammunition type. Firearms with non-adjustable or coarsely adjustable sights cannot give their holders

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3848-434: The mating surfaces to attain the desired fit (clearance). Clearances cannot be too tight, however, or functionality will be compromised; this is very important in automatic and semi-automatic firearms , where there is a certain amount of energy extracted from the firing of the cartridge that must be used to cycle the action. Overly tight clearances mean that there is no place for lubricant and dirt to be, and this can bind

3922-549: The most popular being the KAC M4 Match RAS and a longer-length LaRue free-float handguard, either of which provides plentiful rail space to mount accessories. KAC free-floated rails (P/N 20214) were part of the Mk12 Mod 1 package and were in common use during the war on terror . Barrels were sometimes fitted with Ops Inc. 12th model suppressors and their accompanying muzzle brakes. Accurizing Accurizing

3996-423: The muzzle end of the barrel, providing support for the front sight, but that is bored to much larger than bore diameter. This provides the sight plane of a long barrel with less weight and dwell time. To put lock time and bullet dwell time in perspective; the lock time of most conventional bolt action rifles varies between 2.6 and 9.0 milliseconds , while after cartridge ignition most rifle bullets travel through

4070-621: The normal engagement distances for riflemen. Much like the U.S. Marine Corps SAM-R, the 3rd Infantry division SDM-R was an accurized M16 rifle built in-house by the United States Army Marksmanship Unit with 240 rifles provided for deployment in Iraq. The rifle was informally known as "the AMU rifle". The SAM-R has since been replaced in U.S. Army service, mostly due to the performance of match grade 5.56 NATO ammo in

4144-414: The option of reducing the first stage travel to zero, essentially making the trigger a single-stage trigger. The break is a far more critical stage of the pull, as it happens just prior to the shot being fired. Here again, individual preferences vary; some shooters prefer a soft break, where there is a smooth but discernible amount of trigger travel during firing, while others prefer a crisp break, with

4218-488: The parts. However, except for cost considerations, it is always beneficial to minimize the tolerances applied to the manufacture of mating parts. In some cases, stock parts are not sufficient for the task of producing a finished product with sufficiently tight clearances. In this case, it may be necessary to use specially fabricated parts, built either with minimal clearances (but to a very tight tolerance), or parts that are oversized and intended for hand fitting. The barrel

4292-451: The placement of the shot. Trigger pulls are relative, however. Compare a sport like action shooting , which emphasizes speed and uses relatively close targets with large scoring zones on the targets, to bullseye shooting, which uses distant targets with tiny scoring zones. While both types of trigger need a predictable pull, bullseye shooters demand a much higher degree of precision. The trigger pull consists of three stages: The takeup

4366-477: The point of impact to match the point of aim is relatively simple with any type of adjustable sights, the primary goal of accurizing is to increase the precision of the firearm, which is generally measured by looking at the dispersion of a number of shots fired at the same point of aim. An ideal group would be one where all shots land in a hole no larger than the diameter of a single bullet; this would indicate zero dispersion. The most common way of measuring groups then

4440-456: The question "Which is the most accurate?" becomes a matter of opinion. The 686 shot the best average groups. However, as the Python showed the best performance with one brand of ammunition, it might be the best choice if that brand of ammunition were acceptable for the application in question. If a consistent supply of ammunition were a problem, then the 52 might be the best choice, since it showed

4514-438: The raceway also has a tolerance of +/- 0.001 from the nominal of 0.702, then its ID can vary from 0.701 to 0.703 along its length. That combination of tolerances can allow the bolt clearance to vary from 0.002 to 0.006. The point at which the 0.002 clearance occurred would likely cause binding and malfunction in most operational environments. To ensure consistent, repeatable lockup, clearances between moving parts must be kept to

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4588-484: The rifle was centered less around a rigid specification and more around the concept of an accurized rifle that could share the duties and ammunition of fielded M4 carbines , whilst also being able to engage targets beyond the carbines' range. When further development was handed over to Naval Surface Warfare Center Crane Division , the United States Army incorporated their own concepts and funding into

4662-463: The rifle was individualized to the tastes of the user by the armorer or the SEAL themselves. The stainless-steel barrels were sourced from Lilja Precision Rifle Barrels with a 1:8 (203mm) twist and a unique heavy profile, beginning at 0.980 inches (25mm) in diameter for the first 2.60 inches (66mm) of length, then narrowing down to 0.850 inches (22mm) in diameter, 0.750 inches (19mm) in diameter underneath

4736-429: The rifle, and these are often mounted to an accessory rail beneath the forend. Target slings , unlike carrying slings, are used just on the off hand, usually with a hand stop , and provide stability to the shooter's hold. Palm rests are another device that can be attached to the rail, to allow a shooter to lower their off hand and place their elbow into their body for support. Target stocks also are available with

4810-405: The shooter's grip, so that the knuckles fall into position the same way every time. The ideal grip should allow the shooter to repeatedly grasp the gun, bring it up to shooting position with eyes closed, and be correctly aligned and on target when their eyes are opened; this means the grip provides a consistent placement, and minimal corrections when aiming. Contrary to commonly stated rules of thumb,

4884-443: The shooter's hand as it swells and contracts over time. Stocks for long guns are not as often changed as handgun grips, but a well fitted stock can make a significant difference in accuracy. For shotguns in particular, the placement of the shooter's face on the stock provides the rear aiming point, and the correct drop, toe alignment, and cast-off can greatly enhance accuracy. This was traditionally accomplished by steaming and bending

4958-411: The shooter's potential for error and will generally result in much smaller groups than firing from an unsupported position. Even for a firearm that is going to be shot offhand, accuracy testing from a machine rest will provide an idea of the ultimate attainable accuracy. No matter what the potential laboratory accuracy of a firearm, it does not matter if a human shooter cannot fire it accurately under

5032-498: The sights and rough accuracy estimates, but most shooters consider 10-shot groups to be the minimum for accuracy comparisons. Even defining accuracy can be problematic. An example of this can be shown by the following tests, run by Performance Shooter magazine in December, 1996. The magazine was testing seven brands of .38 Special wadcutter rounds in three different revolvers , a Smith & Wesson Model 686 and Model 52, and

5106-455: The smallest value that will allow proper operation of the mechanism. This goal can be achieved by carefully hand selecting parts and precisely fitting them together, or by manufacturing new parts (bolt, receiver, barrel, etc. to precise dimensions using much tighter tolerances than production components. The best fits are generally attained by selecting slightly oversized parts (or altering stock parts to form an interference fit ) and then lapping

5180-592: The stock, but a simpler solution for modern guns is a set of shims that alter the angle of the stock. Rifle stocks have similar issues of fit, and though the use of sights makes this less vital than in a shotgun, a good fit still helps the shooter to relax and concentrate on fundamentals. The shape of a rifle stock should be suited to its intended use. High combs and vertical pistol grips are ideal for high mounted target sights or scopes and careful, deliberate shooting such as encountered in traditional target shooting, metallic silhouette , or varmint hunting , as they provide

5254-542: The user from developing a fear of the recoil. Determining accuracy is not always a straightforward task, as it depends on a large number of variables. The accuracy of a shot relies on many different factors, which can be broken down into three broad categories: the firearm, the cartridge, and the shooter. Accurizing generally refers to the processes that are applied to the firearm. Techniques relating to producing accurate ammunition are covered in internal and external ballistics , and handloading , and just like accurizing

5328-470: The winner was the Model 686, which shot an average group of 68 millimetres (2.69 in) across the brands of ammunition, with a standard deviation between ammunition types of 14 millimetres (0.54 in). However, the Model 52, while shooting slightly larger groups at 73 millimetres (2.88 in), was far more consistent across the brands, with a standard deviation of only 7.6 millimetres (0.30 in), and

5402-477: Was the most consistent performer of the test. However, if the ammunition was tuned to the gun, the clear winner was the Python, which averaged just 43 millimetres (1.69 in) with its favored brand of ammunition. The Python was also by far the pickiest, however, turning in the largest groups at 154 and 102 millimetres (6.08 and 4.0 in) averages with its least favorite brands, for a standard deviation of 41 millimetres (1.6 in). Based on this test, answering

5476-509: Was to be used, along with the Daniel Defense M4Rail 9.0 handguard. This effort never went beyond the staffing process. SEAL Recon Rifle The SEAL Recon Rifle (nicknamed the " Sniper M4 " and " Recce " ) is an American designated marksman rifle and assault rifle used by the United States Navy SEALs . Essentially a heavily modified M16 rifle , it is intended to provide SEAL snipers and designated marksmen with

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