HK416

Heckler & Koch HK416
            The HK416 is an assault rifle designed and manufactured by Heckler & Koch. It is an improved version of the M4 carbine with many changes, most notably a new style gas system borrowed from the HK G36. It is available as a complete firearm or as an upper receiver kit that fits on any AR-15 type lower receiver.
            The US Army’s Delta Force collaborated with the German arms maker to develop the new carbine. Delta replaced its M4s with the HK416 in 2004 after tests revealed that the piston operating system significantly reduces malfunctions while increasing the life of parts.
            The project was originally called the HK M4, but this was changed in response to a trademark infringement suit filed by Colt Defense. The weapon has been tested by the United States military and is in use with some law enforcement agencies and special operations units. It has been adopted as the standard rifle in two NATO nations as well.

Design details
             The HK416 uses a proprietary gas system derived from the HK G36, replacing the direct impingement gas system used by the standard M16/M4. The HK system uses a short-stroke piston driving an operating rod to force the bolt carrier to the rear. This design prevents combustion gases from entering the weapon’s interior, a shortcoming with direct impingement systems. The reduction in heat and fouling of the bolt carrier group increases the reliability of the weapon and extends the interval between stoppages. It also reduces operator cleaning time and stress on critical components.
             The HK416 is equipped with a proprietary accessory rail forearm with MIL-STD-1913 rails on all four sides. This allows most current accessories, used on M4/M16-type weapons, to be fitted to the HK416. The HK416 rail forearm can be installed and removed without tools by using a bolt locking lug as the screwdriver. The rail forearm is of the 'free-float' variety; it does not contact the barrel and improves accuracy.
             The HK416's barrel is cold hammer-forged with a 20,000 round service life. The cold hammer-forging process provides a stronger barrel for greater safety in case of an obstructed bore or for extended firing sessions. This includes "OTB" (Over-the-beach) capability; the HK416 can be safely fired after being submerged in water and not completely drained.

Variants
             The HK416 is currently available in four different barrel lengths: the D10RS model with a 264 mm (10.4 in) barrel, the 368 mm (14.5 in) barrel length D14.5RS, the D16.5RS fitted with a 419 mm (16.5 in) and the 505 mm (19.9 in) length barrel of the D20RS. The HK417 is a larger version of the HK416 chambered for the full-size 7.62x51mm NATO rifle cartridge. Civilian variants of the HK416 and HK417 were announced in 2007, named MR223 and MR308. Both are semi-automatic rifles with several 'sporterized' features. At the 2009 SHOT Show, these two firearms were introduced to the American civilian market renamed respectively MR556 and MR762.

MAC-10

MAC-10
             The MAC-10 (Military Armament Corporation Model 10, officially the M10) is a highly compact, blowback operated machine pistol developed by Gordon B. Ingram in 1964.
             It is a simple, low-cost design with few moving parts, making it easy to manufacture and maintain.
             The compactness and high rates of fire for these weapons (1,090 to 1,145 rpm for the M-10 and 1,200 rpm or more for the M-11 / M-11A1) worked against them. Their small size made them difficult to fire accurately in full auto, and this, when combined with their high rate of fire, made control challenging; this was a key factor in their never finding much success with the military. However, they did see limited service in Vietnam with Special Forces.
            Besides Military Armament Corporation, MAC-10s and MAC-10 parts have been produced by RPB Industries, Cobray Company,Jersey Arms Works, and Section Five Firearms.

Design
             The MAC-10 was built predominantly from steel stampings. A notched cocking handle protrudes from the top of the receiver, and by turning the handle 90° would lock the bolt, and act as an indicator that the weapon is unable to fire. The MAC-10 has a telescoping bolt, which wraps around the barrel. This allows a more compact weapon, and balances the weight of the weapon over the pistol grip where the magazine is located. The MAC-10 fires from an open bolt, and in addition, the light weight of the bolt results in a rapid rate of fire. The barrel is threaded to accept a suppressor, which worked by reducing the discharge's sound, without attempting to reduce the velocity of the bullet. At the suggestion of the United States Army, Ingram added a small bracket with a small strap beneath the muzzle to aid in controlling recoil during fully-automatic fire.

Calibers and variants
              While the original MAC-10 is chambered for the .45 ACP round, the M-10 is part of a series of machine pistols, the others being: the MAC-11 / M-11A1, which is a scaled down version of the M-10 chambered in .380 ACP; and the M-11/9, which is a smaller 9mm version that has a longer receiver with a shorter profile later made by SWD (Sylvia and Wayne Daniel) and Leinad.
              In the United States, fully automatic MAC-10 machine pistols are NFA articles, and probably the least expensive (relative; Approximate cost as of Q1 2009 is $3,600 US +/-) automatic weapons on the American market. A large number of semi-completed sheet metal frame flats were given serial numbers before the Firearm Owners Protection Act of 1986, and this made it possible to complete the manufacture of registered MAC-10s for the civilian market after the 1986 production freeze took effect. There were also a few thousand semi-automatic pistols and carbines that were based on the original MAC-10 design. These were made in open-bolt and later in closed-bolt designs, in response to ATF rule changes that banned semi-auto open bolt designs, beginning in the early 1980s.
              Masterpiece Arms manufactures a semi-automatic variant of the MAC-10 called the MPA-10. It differs from the original MAC-10 in firing from a closed bolt, as opposed to the open-bolt mechanism of the original MAC-10. This allows for more accuracy than open-bolt fire, and the extra cooling offered by open-bolt firing is unnecessary in a semiautomatic firearm.
              The MPA-10 comes in several versions. The stock model has 6" barrel (visually identical to the original MAC-10), a highly modified version which has the cocking handle on the side and has a scope mount on top is also available. One model has a 10" barrel and has an AR-15 style forearm.
              Masterpiece Arms also manufactures a rifle-like variant with a 16" barrel, shoulder stock, and an AR-15 forearm just like on the 10" model. It is more of a carbine rather than a pistol, but is still based on the MAC-10.

SAR 21

SAR 21
           The SAR 21 ("Singapore Assault Rifle - 21st Century") is a bullpup assault rifle designed and manufactured in Singapore. First revealed and subsequently adopted by the Singapore Armed Forces (SAF) in 1999, it was designed & developed over a four year period and was intended to replace the locally license-built M16S1[1] by the Singaporean Ministry of Defence, Singapore Army and the Chartered Industries of Singapore.Many of its design features are directly intended to counter the weaknesses of the M16 as encountered operationally by some infantrymen.
            The rifle is being sold for export use aside from domestic use. In the United States, it is being marketed by ST Kinetics via its American subsidiary, VT Systems.

Design
          Made of a rugged, high impact polymer, most of the manufacturing is done utilising CNC machines, with ultrasonic welding for the steel-reinforced receiver halves and the gun barrel being cold hammer forged. It uses a modified Kalashnikov/Stoner operating system, boasting higher reliability and lower recoil. The translucent magazine allows precise assessment of current ammo load.
          The SAR 21 is also the first production assault rifle of its class to incorporate a built-in Laser Aiming Device (LAD) (powered by a single "AA" battery) as standard, which can emit visible or infrared beams.The rifle incorporates various patented safety features, such as a Kevlar cheek plate and overpressure vent that protects the shooter in the unlikely event of a chamber explosion or catastrophic failure. It also has an integral 1.5x optical scope that is built into its carrying handle. The scope aids in target acquisition, particularly under low light conditions. The scope is factory-zeroed, and requires minimal further zeroing to suit different users.This minimizes non-training range time.

Variants

SAR 21 Light Machine Gun (LMG) 
         Fitted with an open bolt, it has a heavy 513 mm barrel with an integral folding bipod and a foregrip.

SAR 21 Sharpshooter 
          Same as the basic SAR 21, but has 3.0x optical sight instead of standard 1.5x sight. The sight picture is composed of luminous black paint, allowing easier target engagement at night without use of the LAD.

SAR 21 Grenade Launcher (GL)
           Attached with a CIS 40 mm or M203 grenade launcher. Several sub-variants/prototypes incorporate different targeting modules (or mounted on p-rails) for grenade target acquisition. Known sights to have been used include aiming quadrants, various optical sights and laser fire control systems. 

SAR 21 P-rail
          Has a Picatinny rail in place of its integral optical sight. Charging handle is moved to the left hand side of the weapon (Interchangeable with right side).

SAR 21 Modular Mounting System (MMS)
            Has integral optical sight and LAD removed to allow a wide variety of add-on tactical accessories, such as vertical assault grips, tactical lights and reflex sights. Charging handle is moved to the left hand side of the weapon. Similar to P-rail model with exception of shorter barrel. 

SAR 21 Light Weight Carbine
           A light weight SAR 21 variant was revealed during the Asian Defence Exhibition held in conjunction with Asian Aerospace 2006. The variant boasts an ultra-short barrel, shorter handguards and an integral holo-dot aiming recticle. A Picatinny rail is used as well. 

M16

           The M16 (more formally Rifle, Caliber 5.56 mm, M16) is the U.S. military designation for the ArmaLite AR-15 rifle. Colt purchased the rights to the AR-15 and currently uses that designation only for semi-automatic versions of the rifle.
           The M16 entered United States Army service as the M16A1 in 1964 for deployment in Vietnam. The M16 became the standard US Rifle in the Vietnam War by 1969, replacing the M14 rifle in that role. The US Army retained the M14 in CONUS, Europe, and South Korea until 1970. Since the Vietnam War, the M16 rifle family has been the primary infantry rifle of the U.S. military. With its variants, it has been in use by 15 NATO countries, and is the most produced firearm in its caliber.

Introduction
          The M16 is a lightweight, 5.56 mm caliber, air-cooled, gas-operated, magazine-fed assault rifle, with a rotating bolt, actuated by direct impingement gas operation. The rifle is made of steel, aluminum, and composite plastics.
           The U.S. Air Force's rifle, the M16, and the United States Marines and Army rifle, the XM16E1, were the first versions of the M16 rifle fielded. Soon, the Army standardized the XM16E1 as the M16A1 rifle, an M16 with a forward assist feature requested by the Army. All of the early versions were chambered to fire the M193/M196 cartridge in the semi-automatic and the automatic firing modes. This occurred in the early 1960s, with the Army issuing it in late 1964. Commercial AR-15s were first issued to Special Forces troops in spring of 1964. 
            The M16A2 rifle entered service in the 1980s, chambered to fire the standard NATO cartridge, the Belgian-designed M855/M856 cartridge. The M16A2 is a select-fire rifle (semi-automatic fire, three-round-burst fire) incorporating design elements requested by the Marine Corps: an adjustable, windage rear-sight; a stock 5/8-inch longer; heavier barrel; case deflector for left-hand shooters; and cylindrical hand guards. The fire mode selector is on the receiver's left side. The M16A2 is still the primary rifle in the U.S. Navy, Coast Guard, Air Force, and still is in heavy use in the Army and Marine Corps.
            The M16A3 rifle is an M16A2 rifle with an M16A1's fire-mode control (semi-automatic fire, automatic fire) used only by the U.S. Navy.
            The M16A4 rifle was standard issue for the United States Marine Corps in Operation Iraqi Freedom; it replaced the M16A2 in front line units. In the U.S. Army the M16A2 rifle is being supplemented with two rifle models, the M16A4 and the M4 Carbine as the standard issue Assault rifle. The M16A4 rifle has a flat-top receiver developed for the M4 Carbine, a handguard with four Picatinny rails for mounting a sight, laser, night vision device, forward handgrip, removable handle, or a flashlight.
            The M16 rifle is principally manufactured by the Colt and the Fabrique Nationale de Herstal arms companies, with the variant rifles made elsewhere in the world. Versions for the U.S. military have also been made by H & R Firearms General Motors Hydramatic Division and most recently by Sabre Defence Industries. The semi-automatic versions of the M16 rifle, generally called the "AR-15" (Colt bought the nomenclature from Armalite), are popular, recreational shooting rifles, with versions manufactured by other small and large manufacturers in the U.S.
 
Design details 
            The M16's receivers are made of aluminium alloy, its barrel, bolt, and bolt carrier of steel, and its handguards, pistol grip, and buttstock of plastics. Early models were especially lightweight at 6.5 lb (2.9 kg) without magazine and sling. This was significantly less than older 7.62 mm "battle rifles" of the 1950s and 1960s. It also compares with the 6.5 lb (2.9 kg) AKM without magazine.[15] M16A2 and later variants weigh more (8.5 lb (3.9 kg) loaded) because of the adoption of a thicker barrel profile. The thicker barrel is more resistant to damage when handled roughly and is also slower to overheat during sustained fire. Unlike a traditional "bull" barrel that is thick its entire length, the M16A2's barrel is only thick forward of the handguards. The barrel profile under the handguards remained the same as the M16A1 for compatibility with the M203 grenade launcher. The rifle is the same length as the M16A2.
             One distinctive ergonomic feature is a plastic or metal stock directly behind the action, which contains a recoil spring. This serves the dual function of operating spring and recoil buffer.  The stock being in line with the bore reduces muzzle rise, especially during automatic fire. Because recoil does not significantly shift the point of aim, faster follow-up shots are possible and user fatigue is reduced.

             Another distinctive ergonomic feature is a carrying handle on top of the receiver, with an integrated rear sight assembly and charging handle. This design is a by-product of the original design where the carry handle served to protect the charging handle and mount a scope. In practice, the handle is rarely used to carry the weapon and doing so is expressly prohibited in many military organizations, as it is considered unsafe. Holding the weapon by the pistol grip provides quicker response time and better "muzzle awareness," while a shoulder sling provides a more convenient option when response time is not a concern. More importantly, with the sight plane 2.5 in (63.5 mm) over the bore, the M16 has an inherent parallax problem that can be confounding to shooters. At closer ranges (typically inside 15–20 meters), the shooter must aim high in order to place shots where desired.
             Newer models have a "flattop" upper receiver with a Picatinny mounting rail, to which the user can attach either a conventional sighting system or numerous optical devices such as night vision scopes.

             The M16 utilizes direct impingement gas operation; energy from high-pressure gas tapped from a non-adjustable port built into the front sight assembly actuates the moving parts in the weapon. Combustion gases travel via a gas tube above the barrel directly into a chamber in the bolt carrier behind the bolt itself, pushing the carrier away from the bolt. This reduces the number of moving parts by eliminating the need for a separate piston and cylinder and it provides better performance in rapid fire by keeping reciprocating masses on the same axis as the bore.

              A U.S. Marine with an M16A4 equipped with an ACOG

              The primary criticism of direct impingement is that fouling and debris from expended gunpowder is blown directly into the breech. As the superheated combustion gas travels down the tube, it expands and cools, not unlike an aerosol can cooling when depressurized. This cooling causes vaporized matter to condense as it cools depositing a much greater volume of solids into the operating components of the action. The increased fouling can cause malfunctions if the rifle is not cleaned as frequently as should be. The amount of sooting deposits tends to vary with powder specification, caliber, and gas port design.

Variants 
AR-15 (Colt Models 601 & 602) 
             Colt's first two models produced after the acquisition of the rifle from ArmaLite were the 601 and 602, and these rifles were in many ways clones of the original ArmaLite rifle (in fact, these rifles were often found stamped Colt ArmaLite AR-15, Property of the U.S. Government caliber .223, and no reference to being a M16). The 601 and 602 are easily identified by their flat lower receivers without raised surfaces around the magazine well and occasionally green or brown furniture. The 601 was adopted first of any of the rifles by the USAF, and was quickly supplemented with the XM16 (Colt Model 602) and later the M16 (Colt Model 604) as improvements were made. There was also a limited purchase of 602s, and a number of both of these rifles found their way to a number of Special Operations units then operating in South East Asia, most notably the U.S. Navy SEALs. The only major difference between the 601 and 602 is the switch from the original 1:14-inch rifling twist to the more common 1:12-inch twist. These weapons were equipped with a triangular charging handle and a bolt hold open device that lacked a lower engagement surface. The bolt hold open device had to be engaged with a bare thumb or a thumb nail because of the lack of this surface.

               The United States Air Force continued to use the AR-15 marked guns in various configurations into the 1990s.

M16
             Variant originally adopted by the U.S. Air Force. This was the first M16 adopted operationally. This variant had triangular handguards, a three-pronged flash suppressor, and no forward assist. Bolt carriers were originally chrome plated and slick-sided, lacking forward assist notches. Later, the chrome plated carriers were dropped in favor of Army issued notched and parkerized carriers though the interior portion of the bolt carrier is still chrome-lined. The Air Force continues to operate these weapons and upgrades them as parts wear or break and through attrition.
             Also used by the SAS, which used it to effect during the Falklands War.
 
XM16E1 and M16A1
           The U.S. Army XM16E1 was essentially the same weapon as the M16 with the addition of a forward assist and corresponding notches in the bolt carrier. The M16A1 was the finalized production model in 1967. To address issues raised by the XM16E1's testing cycle, a closed, bird-cage flash suppressor replaced the XM16E1's three-pronged flash suppressor which caught on twigs and leaves. Various other changes were made after numerous problems in the field. Cleaning kits were developed and issued while barrels with chrome-plated chambers and later fully-lined bores were introduced.
              With these and other changes, the malfunction rate slowly declined and new soldiers were generally unfamiliar with early problems. A rib was built into the side of the receiver on the XM16E1 to help prevent accidentally pressing the magazine release button while closing the ejection port cover. This rib was later extended on production M16A1s to help in preventing the magazine release from inadvertently being pressed. The bolt cam pin and the hole it rides in the bolt were tapered to prevent the bolt from being inserted upside down (creating a failure to fire). The M16A1 remains in service in limited numbers in the United States but is still standard issue in many world armies.

M16A2
               The development of the M16A2 rifle was originally requested by the United States Marine Corps as a result of the USMC's combat experiences in Vietnam with the XM16E1 and M16A1.[4] The Marines were the first branch of the U.S. Armed Forces to adopt the M16A2 in the early/mid 1980s with the United States Army following suit in adopting the M16A2 in the late 1980s. Modifications to the M16A2 were more extensive. In addition to the new rifling, the barrel was made with a greater thickness in front of the front sight post to resist bending in the field and to allow a longer period of sustained fire without overheating. The rest of the barrel was maintained at the original thickness to enable the M203 grenade launcher to be attached. The front sight was now a square post with 4 detent positions, adjustable for vertical zeroing by using a cartridge, nail or special tool. A new adjustable rear sight was added, allowing the rear sight to be dialed in for specific range settings between 300 and 800 meters to take full advantage of the ballistic characteristics of the new SS109 rounds and to allow windage adjustments without the need of a tool or cartridge. The flash suppressor was again modified, this time to be closed on the bottom so it would not kick up dirt or snow when being fired from the prone position, and acting as a recoil compensator. The front grip was modified from the original triangular shape to a round one, which better fitted smaller hands and could be fitted to older models of the M16. The new handguards were also symmetrical so that armories needn't separate left and right spares. The handguard retention ring was angled to make it easier to install and uninstall the handguards. The pistol grip adds a notch for the middle finger and more texture to enhance the grip. The buttstock was lengthened by 5/8 inch (16 mm). The new buttstock became ten times stronger than the original due to advances in polymer technology since the early 1960s. Original M16 stocks were made from fiberglass-impregnated resin; the newer stocks were engineered from DuPont Zytel glass-filled thermoset polymers. The new stock included a fully textured polymer buttplate for better grip on the shoulder, and retained a panel for accessing a small compartment inside the stock, often used for storing a basic cleaning kit. The heavier bullet reduces muzzle velocity from 3,200 feet (980 m) per second (975 m/s), to about 3,050 feet (930 m) per second (930 m/s). The A2 also uses a faster twist rifling to allow the use of a trajectory-matched tracer round. A spent case deflector was incorporated into the upper receiver immediately behind the ejection port to prevent casings from striking left-handed users.

           The action was also modified, replacing the fully-automatic setting with a three-round burst setting.[4] When using a fully-automatic weapon, poorly trained troops often hold down the trigger and "spray" when under fire. The U.S. Army concluded that three-shot groups provide an optimum combination of ammunition conservation, accuracy and firepower. There are mechanical flaws in the M16A2 burst mechanism. The trigger group does not reset when the trigger is released. If the user releases the trigger between the second and third round of the burst, for example, the next trigger pull would only result in a single shot. Even in semi-automatic mode, the trigger group mechanism affects weapon handling. With each round fired, the trigger group cycles through one of the three stages of the burst mechanism. Worse, the trigger pull at each of these stages may vary as much as 6 lbf (27 N) in pressure differential, detracting from accuracy.

           All together, the M16A2s new features added weight and complexity to the M16 series. Critics also point out that neither of the rear sight apertures is ideally sized. The smaller aperture was described as being too small, making quick acquisition of the front sight post difficult; and the larger aperture was described as being too large, resulting in decreased accuracy. To make matters worse, the rear sight apertures are not machined to be on the same plane. In other words, the point of impact changes when the user changes from one aperture to the other. The rear sight's range adjustment feature is rarely used in combat as soldiers tend to leave the rear sight on its lowest range setting: 300 meters. Despite criticism, a new rifle was needed both to comply with NATO standardization of the SS109 (M855) and to replace aging Vietnam era weapons in the inventory.

M16A3
          The M16A3 was a fully-automatic variant of the M16A2 adopted in small numbers around the time of the introduction of the M16A2, primarily by the U.S. Navy for use by SEAL, Seabee, and Security units.[23] It features the M16A1 trigger group providing "safe", "semi-automatic", and "fully-automatic" modes.

           The M16A3 is often incorrectly described as the fully-automatic version of the M16A4 or an M16A2 with a Picatinny rail. This misunderstanding likely stems from the use of the "A3" designation by Colt and other manufacturers to describe commercial AR-15 type rifles before the official adoption of the M16A3 or M16A4. Colt used the "A3" designation in the hopes of winning military contracts as they also did with the terms, "M4" and "M5".

M16A4
          The M16A4, now standard issue for front-line U.S. Marine Corps and some U.S. Army units, replaces the combination fixed carry handle/rear iron sight with a MIL-STD-1913 Picatinny rail, allowing for the rifle to be equipped with a carry handle and/or most military and consumer scopes or sighting systems (usually either an ACOG, EO tech, or M68 CCO). Most of the U.S. Marine Corps' M16A4s are equipped with a Knight's Armament Company M5 RAS handguard, allowing vertical grips, lasers, tactical lights, and other accessories to be attached. In U.S. Army Field Manuals, M16A4s fitted with the RAS are sometimes referred to as M16A4 MWS or Modular Weapon System. This model retains the 3-round burst mode of the M16A2. 
 
 

MP5

Heckler & Koch MP5

         The Heckler & Koch MP5 (From Maschinenpistole 5 - German: "machine pistol model 5") is a 9mm submachine gun of German design, developed in the 1960s by a team of engineers from the German small arms manufacturer Heckler & Koch GmbH (H&K) of Oberndorf am Neckar.
          It is currently used by the armed forces and law enforcement units of over 40 countries. The MP5 remains one of the most widely deployed of all current submachine guns and has been developed into a family with numerous variants.
          In the 1990s, Heckler & Koch developed the Heckler & Koch UMP, the MP5's successor, though both remain in production.

History
          Heckler & Koch, encouraged by the success of the G3 automatic rifle, developed a family of small arms consisting of four types of firearms (all based on a common G3 design layout and operating principle), where the first type was chambered in 7.62x51mm NATO, the second—using the 7.62x39mm M43 round, third—the intermediate 5.56x45mm NATO caliber and the fourth type—chambering the 9x19mm Parabellum pistol cartridge. The MP5 was created within the fourth group of firearms and was initially known as the HK54.
         Work on the MP5 began in 1964 and scarcely two years later it was adopted by the German Federal Police, border guard and army special forces.
          The submachine guns are manufactured under license in several nations including: Greece (formerly at EBO - Hellenic Arms Industry, currently at EAS - Hellenic Defense Systems), Iran (Defense Industries Organization), Mexico (SEDENA), Pakistan (Pakistan Ordnance Factories), Sudan (Military Industry Corporation), Turkey (MKEK), and the United Kingdom (initially at Royal Ordnance, later diverted to Heckler & Koch Great Britain).

Design details
         The primary version of the MP5 submachine gun family is the MP5A2, which is a lightweight, air-cooled, selective fire delayed blowback operated 9x19mm Parabellum weapon with a roller-delayed bolt. The weapon fires from a closed bolt (bolt forward) position.
The fixed, free floating, cold hammer-forged barrel has 6 right-hand grooves with a 1 in 250 mm (1:10 in) rifling twist rate and is pressed and pinned into the receiver.

Variants
      MP5A1: No buttstock (endplate/receiver cap in place of buttstock), "Navy"/"SEF" trigger group.
      MP5A2: Fixed buttstock, "SEF" trigger group.
      MP5SFA2: Fixed buttstock, single-fire (SF) trigger group.
      MP5A3: Retractable buttstock,"SEF" trigger group.
      MP5SFA3: Retractable buttstock, single-fire (SF) trigger group.
      MP5A4: Fixed buttstock, 3-round burst trigger group.
      MP5A5: Retractable buttstock, 3-round burst trigger group.
      MP5-N: Model developed specifically for the U.S. Navy. Ambidextrous "Navy" trigger group, 3-lug/threaded barrel for attaching a sound suppressor; retractable stock.
      MP5F: Model developed specifically for the French military. Rubber-padded retractable stock, ambidextrous sling loops/bolts and internal modifications to handle high-pressure ammunition.
      MP5K: Short (Kurz) version, "SEF" trigger group.
      MP5KA1: MP5K with smooth upper surface and small iron sights; "SEF" trigger group.
      MP5KA4: MP5K with 3-round burst trigger group.
      MP5KA5: MP5KA1 with 3-round burst trigger group.
      MP5K-N: MP5K with "Navy" trigger group and 3-lug/threaded barrel for mounting suppressors or other muzzle attachments.
      MP5K-PDW: Personal Defense Weapon; MP5K-N with added folding stock and 3-lug/threaded barrel for mounting of suppressors; "Navy" or 3-round burst trigger group. Introduced in 1991.
      MP5SD1: No buttstock (endplate/receiver cap in place of buttstock), "SEF" trigger group, integrated suppressor (Schalldämpfer)
      MP5SD2: Fixed buttstock, "SEF" trigger group, integrated suppressor.
      MP5SD3: Retractable buttstock, "SEF" trigger group, integrated suppressor.
      MP5SD4: No buttstock (endplate/receiver cap in place of buttstock), 3-round burst trigger group, integrated suppressor.
      MP5SD5: Fixed buttstock, 3-round burst trigger group, integrated suppressor.
      MP5SD6: Retractable buttstock, 3-round burst trigger group, integrated suppressor.
      MP5SD-N1: Retractable buttstock, "Navy" trigger group, KAC stainless steel suppressor.
      MP5SD-N2: Fixed buttstock, "Navy" trigger group, KAC stainless steel suppressor.
      MP5/10: Chambered in 10mm Auto, available in various stock/trigger group configurations. It was produced from 1992 to 2000.
      MP5/40: Chambered in .40 S&W, available in various stock/trigger group configurations. It was produced from 1992 to 2000.
      HK94: American import model of the MP5 with a 16 in barrel and special safe/semi-automatic trigger group, designed for civilian use. It was made from 1983 to 1989, in three different configurations.
SP89: Sport Pistole M1989. Semi-automatic only version of the MP5K designed for civilian use. It had a modified foregrip redesigned into a traditional handguard to make it compliant with the Semi-Auto Weapons Ban of 1989. It was made from 1989 to 1994.
       HK54: This was the original model that was produced in the mid 1960s. It later became known as the              MP5A1, a very slightly modified version.
 

HK50

HK50
          The G36 is a German 5.56mm assault rifle, designed in the early 1990s by Heckler & Koch (H&K) and accepted into service with the Bundeswehr in 1997, replacing the 7.62mm G3 battle rifle.
Development
                Work on a successor for the venerable G3 rifle had been ongoing in Germany since the second half of the 1970s. These efforts resulted in the innovative 4.73 mm G11 assault rifle (developed jointly by a group of companies led by H&K), that used caseless ammunition (designed by the Dynamit Nobel company). It had been predicted that this weapon would eventually replace the G3, therefore further development of H&K's series of firearms chambered for the 5.56x45mm NATO cartridge had been halted. Heckler & Koch had no incentive to pursue a new 5.56 mm weapon design, content with the export-oriented HK33 and G41 assault rifles. However, the G11 program came to an abrupt end when the Bundeswehr rejected the design due to defense budget cuts after the unification of East and West Germany and H&K was acquired in 1991 by British Aerospace's Royal Ordnance division (known today as BAE Systems).

Increasing interest in Germany for a modern service rifle chambered for the NATO-standard 5.56 mm cartridge led H&K to offer the German armed forces the G41 rifle, which too was declined. Design work was then initiated from the ground up on a modern 5.56 mm assault rifle, designated "Project 50" or HK50.[1] The prototype was then trialled, where it was rated higher than the rival Austrian Steyr AUG system.

Design details
         The G36 is a selective fire 5.56mm assault rifle, firing from a closed rotary bolt. The G36 has a conventional layout and a modular component design. Common to all variants of the G36 family are: the receiver and buttstock assembly, bolt carrier group with bolt and the return mechanism and guide rod. The receiver contains the barrel, carry handle with integrated sights, trigger group with pistol grip, handguard and magazine socket. 
             The G36 employs a free-floating barrel (the barrel does not contact the handguard). The barrel is fastened to the receiver with a special nut, which can be removed with a wrench. The barrel is produced using a cold hammer forging process and features a chrome-lined bore with 6 right-hand grooves and a 1 in 178 mm (1:7 in) rifling twist rate. The barrel assembly consists of the gas block, a collar with a bayonet lug that is also used to launch rifle grenades and a slotted flash suppressor.     
       The weapon can be stripped and re-assembled without tools through a system of cross-pins similar to that used on earlier HK designs. For cleaning purposes, the G36 disassembles into the following groups: receiver housing, return mechanism, bolt carrier group and trigger group.

Features
        The fire and safety selector is ambidextrous and has controls on both sides of the receiver; the selector settings are described with letters: “S” – safe, “E” – semi-automatic fire and “F” – continuous fire.[1] The weapon safety disables the trigger when engaged. HK also offers several other trigger options, including the so-called “Navy” trigger group, with settings analogous to the standard trigger, but the selector positions have been illustrated with pictograms. A semi-automatic only trigger unit (lacks the “F” setting) is also available. An integrated, manual safety mechanism prevents accidental firing (this is an improved trigger group from the G3 rifle).
        The G36 feeds from proprietary 30-round curved magazines with cartridges loaded in a staggered pattern. The magazines are molded from a high-strength translucent polymer and can be clipped together using built-in coupling studs into 2 or 3-magazine packs allowing up to five magazines to be carried side-by-side on the rifle ready for rapid magazine changes. The magazines are not compatible with NATO-standard STANAG magazines, as introduced in the M16. However, the G36 can be used with Beta C-Mag drum magazines (produced by Beta Company), that have a 100-round cartridge capacity and are intended to be used primarily with the MG36 light support weapon.
        The weapon is equipped with a side-folding skeletonized stock and a detachable folding bipod, which folds into recesses in the handguard. The G36 can be fired with the stock collapsed. The underside of the butt-stock has holes into which assembly pins can be placed during weapon cleaning and maintenance.
        The G36 employs a large number of lightweight, corrosion-resistant synthetic materials in its design; the receiver housing, stock, trigger group (including the fire control selector and firing mechanism parts), magazine well, handguard and carry handle are all made of a carbon fiber-reinforced polyamide. The receiver has an integrated steel barrel trunnion (with locking recesses) and the reciprocating parts move on steel rails molded into the receiver (this feature was issued a US patent, number 5513461, authored by Helmut Weldle).

Variants 

         The MG36 light machine gun differs from the G36, having a heavier barrel for an increased heat and cook-off resistance.
          The G36K (K - kurz or short) carbine has a shorter barrel (fitted with an open-type flash suppressor) and a shorter handguard, which includes a bottom rail that can be used to attach tactical accessories, such as a UTL halogen flashlight from the USP pistol. The carbine’s barrel lacks the capability to launch rifle grenades and it cannot mount a bayonet. The weapon retained the ability to be used with the AG36 grenade launcher. G36Ks in service with German special forces are provided with 100-round C-MAGs.
           The G36C (C – Compact) is a further development of the G36K. It has a shorter barrel (than the G36K), and a 4-prong open-type flash suppressor. The use of a reduced length 228 mm barrel forced designers to move the gas block closer to the muzzle end and use a shortened gas piston rod. The handguard and stock were also reduced in length and the fixed carry handle (with optical sights) was replaced with a carry handle with an integrated MIL-STD-1913 Picatinny rail. In place of the dual optical sight found on the regular G36 and G36K, the G36C was equipped with rail-mounted iron sights that consist of a hooded front post and a flip rear aperture. The short handguard has six attachment points, one of which could be used for a vertical foregrip.
           The G36A2 is an in-service designation allocated to an upgraded variant of the G36 used by the German Army. The G36A2 is equipped with a quick detachable Zeiss RSA reflex red dot sight[6] mounted on a Picatinny rail that replaces the original red dot sight of the dual combat sighting system. The G36A2 upgrade kit also consists of a new handguard with three Picatinny rails and a handgrip with an integrated switch for operating an Oerlikon Contraves LLM01 laser light module. 


 

AK-74

       
AK-74
             The AK-74 (Kalashnikov Automatic Rifle, Model 1974 (Russian: Автомат Калашникова образца 1974 года) is a 5.45mm assault rifle developed in the early 1970s in the Soviet Union by Mikhail Kalashnikov. It was developed from the earlier AKM (itself a refinement of the AK-47) and introduced in 1974. The rifle first saw service with Soviet forces engaged in the Afghanistan conflict.[1] Presently, the rifle is used by the majority of countries of the former USSR. Additionally, unlicensed copies were produced in Bulgaria (AK-74 and AKS-74U), China (Type 88), the former East Germany (MPi-AK-74N, MPi-AKS-74N, MPi-AKS-74NK) and Romania (PA md. 86).

Design details
            The AK-74 is an adaptation of the 7.62mm AKM assault rifle and features several important design improvements.[1] These modifications were primarily the result of converting the rifle to the intermediate-caliber 5.45x39mm cartridge, in fact, some early models are reported to have been converted AKMs, with the barrel resleeved to 5.45x39mm.[3] The result is a more accurate and reliable rifle than the AKM.[1] The AK-74 and AKM share an approximate 50% parts commonality (interchangeable are most often pins, springs and screws).

             The rifle’s operation during firing and reloading is identical to that of the AKM.[4] After ignition of the cartridge primer and propellant, rapidly expanding exhaust gases are diverted into the gas cylinder above the barrel through a vent near the muzzle. The build-up of gases inside the gas cylinder drives the long-stroke piston and bolt carrier rearward and a cam guide machined into the underside of the bolt carrier rotates the bolt approximately 35° and unlocks it from the barrel extension via a camming pin on the bolt. The moving assembly has about 5.5 mm (0.2 in) of free travel which creates a delay between the initial recoil impulse of the piston and the bolt unlocking sequence, allowing gas pressures to drop to a safe level before the seal between the chamber and the bolt is broken. Like previous Kalashnikov-pattern rifles, the AK-74 does not have a gas valve; excess gases are ventilated through a series of radial ports in the gas cylinder. Since the Kalashnikov operating system offers no primary extraction upon bolt rotation, the AK-74 bolt has a larger extractor claw than the 7.62mm AKM for increased extraction reliability.[5] Other minor modifications were made to the bolt and carrier assembly.

            The rifle received a new barrel with a chrome-lined bore and 4 right-hand grooves at a 200 mm (1:8 in) rifling twist rate. The front sight base and gas block were redesigned. The gas block contains a gas channel that is installed at a 90° angle in relation to the bore axis. A pair of support brackets are cast into the gas block assembly and are used to attach a BG-15 or GP-25 under-slung 40 mm grenade launcher. The forward section of the front sight base features a threaded collar that is used to screw in a newly-designed multifunction muzzle device (performing the role of a muzzle brake, recoil compensator and flash suppressor) or a blank-firing adaptor. The muzzle device is held in place by a spring-loaded button and is quickly detachable. The distinctive muzzle brake features a large expansion chamber, two symmetrical vertical cuts at the forward end of the brake and three vent holes positioned to prevent muzzle climb and lateral shift to the right (for right-handed shooters). A flat plate near the end of the brake produces a forward thrust when emerging exhaust gases strike its surface, eliminating nearly all felt recoil. The muzzle brake prevents backblast from reaching the firer, although it is reported to be harsh on bystanders as the muzzle gases are dispersed to the sides.

Variants
AKS-74
             The AKS-74 ("S"—So skladnym prikladom) is a variant of the AK-74 equipped with a side-folding metal shoulder stock, designed primarily for use with air assault infantry and developed alongside the basic AK-74. Unlike the AKMS's somewhat fragile underfolding stock (modeled after the MP 40 submachine gun stock), the AKS-74 stock is fabricated from stamped sheet metal struts, machine pressed into a "U" shape and assembled by punch fit and welding. The stock has a triangular shape; it lacks the folding shoulder pad found on the AKMS stock and is folded to the left side of the receiver. The hinged stock is securely locked in its extended position by a spring-loaded button catch located at the rear of the receiver, on the left side. When folded, the stock is held closed by a spring-loaded capture hook situated on the left side at the front of the receiver housing. A rear-mounted sling swivel is also provided on the right side at the beginning of the stock frame.
AKS-74U
              In 1979, a shortened carbine variant of the AKS-74 was adopted into service with the Red Army: the AKS-74U (U—Ukorochenniy), which in terms of tactical deployment, bridges the gap between a submachine gun and an assault rifle. It is intended for use mainly with special forces, airborne infantry, rear-echelon support units and armored vehicle crews. The rifle's compact dimensions, compared to the AKS-74, were achieved by using a short 210 mm (8.3 in) barrel (this forced designers to simultaneously reduce the gas piston operating rod to an appropriate length). In order to effectively stabilize projectiles, the barrel’s twist rate was increased from 200 mm (1:8 in) to 160 mm (1:6.3 in). A new gas block was installed at the muzzle end of the barrel with a new conical flash hider combined with a cylindrical muzzle booster, which features an internal expansion chamber that increases the weapon's reliability. The booster enhances the recoil impulse by supplying the gas system with residual gases from the barrel. The chrome-lined muzzle booster also burns any remaining propellant thus reducing the gun's signature. The muzzle device locks into the gas block with a spring-loaded detent and features two notches cut into the flash hider cone, used for disassembly using the supplied cleaning rod. The forward sling loop was relocated to the left side of the carbine and the front sight was integrated into the gas block.

              The AKS-74U also has a different sighting system with a U-shaped flip sight instead of the standard sliding notch rear sight. This sight has two settings: "P" (calibrated for firing at 350 m) and "4–5" (used for firing at distances between 400–500 m). The rear sight is housed in a semi-shrouded protective enclosure that is riveted to the receiver's top cover. This top cover is integral with the gas tube cover and hinged from the barrel trunnion, pivoting forward when opened. Both the gas tube and handguard are also of a new type and are shorter than the analogous parts in the AKS-74.

                The AKS-74U is significantly more maneuverable in tight quarters than the AKS-74, however the significant decline in muzzle velocity from 900 m/s (2,952.8 ft/s) to 735 m/s (2,411.4 ft/s) resulted in a decrease in effective range (the effective hitting distance for a "running"-type silhouette target was reduced from 625 to 350 m). The carbine cannot mount a bayonet or standard under-barrel grenade launcher. However, a suppressed 30 mm BS-1 grenade launcher was developed specifically for that platform that fires a high-explosive dual purpose (HEDP) grenade. The grenades for the BS-1 are launched by blank cartridges and the rifle is cycled manually in this mode of operation. The majority of AKS-74U carbines were manufactured at the Tula Arms Factory rather than Izhmash. The AKS-74U was also used as the basis for several other unique weapons, including the bullpup OTs-14 Groza specialist carbine and the Gepard series of multi-caliber submachine guns (none of which evolved past prototype stage).

AK-74M
               In 1991 the Izhmash factory in the city of Izhevsk began production of an improved variant of the AK-74 – the AK-74M (M – Russian: Модернизированный; Modernizirovanniy or "modernized") assault rifle. Apart from several minor production improvements the rifle also features a new synthetic stock made from a black, glass-filled polyamide that is shaped like the AK-74 fixed stock, but also folds like in the AKS-74. Additionally the AK-74M uses a reinforced muzzle device and dust cover. Each AK-74M is fitted with a side-rail bracket for mounting optics. The AK-74M would have been adopted by the Soviet Union as the standard service rifle, and has been accepted as the new service rifle of the Russian Federation.

AK-100 series
            The AK-74 was also the basis for the new Russian family of Kalashnikov firearms: the 5.56 mm AK-101 standard rifle and 5.56 mm AK-102 carbine (both use the NATO-standard 5.56x45mm cartridge), 7.62 mm AK-103 assault rifle and 7.62 mm AK-104 (both chambered for the 7.62x39mm M43 round) and the 5.45 mm AK-105 carbine (adapted to use 5.45x39mm M74 ammunition). The AK-101, 102, 103 and 104 are destined primarily for export, while the AK-105 is slated to replace the AKS-74U with the Russian Armed Forces.

M4A1

M4 carbine
              TheM4 carbine is a family of firearms tracing its lineage back to earlier carbine versions of the M16, all based on the original AR-15 made by ArmaLite. It is a shorter and lighter version of the M16A2 assault rifle, achieving 80% parts commonality with the M16A2.[1] The M4 has selective fire options including semi-automatic and three-round burst (like the M16A2), while the M4A1 has a "full auto" option in place of the three-round burst.
Overview 
              The M4 and variants fire 5.56x45mm NATO ammunition and are gas-operated, air-cooled, magazine-fed, selective fire firearms with a 4-position telescoping stock. Original M4 models had a flat-ended telescoping stock, but newer models are now equipped with a redesigned telescoping stock that is slightly larger with curvature at the end. The M4 is similar to much earlier compact M16 versions, such as the 1960s-era XM177 family. Some of those visual designs are obvious in both weapons, however most of the similarities are not very noticeable.
              As with many carbines, the M4 is handy and more convenient to carry than a full-length rifle. The price is slightly inferior ballistic performance compared to the full-size M16, with its nearly 6" (15 cm) longer barrel. This becomes most apparent at ranges of 300 yards and beyond. Statistically, however, most small-arms engagements occur within 100 yards. This means that the M4 is very much an adequate weapon for the majority of troops. The marginal sacrifice in terminal ballistics and range, in exchange for greatly improved handling characteristics, is usually thought to be a worthwhile compromise.
              While the M4's maneuverability makes it a candidate for non-infantry troops (vehicle crews, clerks and staff officers), it also makes it ideal for close quarters battle (CQB), and airborne and special operations, which is the most popular usage for the weapon. It has been adopted by United States Special Operations Command (USSOCOM) and is the preferred weapon of the U.S. Army Special Forces and Navy SEALs. The M4 was developed and produced for the United States government by Colt Firearms, which has an exclusive contract to produce the M4 family of weapons through 2009; however, a number of other manufacturers offer M4-like firearms. The M4A1, along with the M16A4, has mostly replaced the M16A2; the U.S. Air Force, for example, plans to transition completely to the M4 Carbine. The M4 Carbine is also the standard rifle for U.S. Air Force Security Forces members whether at home station or deployed abroad. They maintain a yearly qualification on it.
             The United States Marine Corps has ordered its officers (up to the rank of lieutenant colonel) and Staff Non-commissioned officers to carry the M4A1 carbine instead of the M9 handgun. This is in keeping with the Marine Corps motto, "Every Marine a rifleman." United States Navy corpsmen will also be issued M4A1s instead of the M9. 
History 
           Except for the very first delivery order, all U.S. military-issue M4 and M4A1 possess a flat-top NATO M1913-specification (Picatinny) rail on top of the receiver for attachment of optical sights and other aiming devices — Trijicon TA01 and TA31 Advanced Combat Optical Gunsights (ACOG), EOTech 550 series holographic sights, and Aimpoint M68 Close Combat Optic (M68 CCO) being the favorite choices — and a detachable rail-mounted carrying handle. Standards are the Colt Model 920 (M4) and 921 (M4A1).
Design
           The M4/M4A1 5.56 mm Carbine is a gas-operated, air-cooled, magazine-fed, selective fire, shoulder-fired weapon with a telescoping stock. A shortened variant of the M16A2 rifle with a 14.5 in (368 mm) barrel, the M4 provides the individual soldier operating in close quarters the capability to engage targets at extended range with accurate, lethal fire. The original M4 Carbine has semi-automatic and three-round burst fire modes, while the M4A1 has "semi" and "full auto", with no three-round burst. The M4 Carbine achieves over 80% commonality with the M16A2 rifle and was intended to replace the .45 ACP M3 submachine guns and selected M9 pistols and M16 rifle series with most Army units (this plan was thought to be changed with the development of the XM29 OICW and the XM8 carbine. However, both projects were cancelled). The M4 Carbine is also capable of mounting the M203 grenade launcher, the M203A1 with a 9-inch barrel as opposed to the standard 12-inch barrel of the M203 used on the M16 series of rifle.

Accessories 
            Like all the variants of the M16 assault rifle, the M4 Carbine and the M4A1 Carbine can be fitted with many accessories, such as night vision devices, suppressors, laser pointers, telescopic sights, bipods, either the M203 or M320 grenade launchers, the M26 MASS shotgun, and anything else compatible with a MIL-STD-1913 Picatinny rail.
           Other common accessories include the AN/PEQ-2, Advanced Combat Optical Gunsight (ACOG), and M68 Aimpoint. EOTech holographic weapon sights are to be part of the SOPMOD II package. Visible and IR (infrared) lights of various manufacturers are also commonly attached using various mounting methods. As with all versions of the M16, the M4 accepts a blank-firing attachment (BFA).


 

Magpul Masada

Bushmaster ACR

            The original Magpul Masada design represents an amalgamation of several recent rifle designs, incorporating what is considered by its designers to be the best features of each in a single, lightweight, modular rifle platform. Design features from the Armalite AR-18 (short-stroke gas system), the FN SCAR (upper receiver, charging handle location), the Heckler & Koch G36/XM8 (liberal use of polymer components), the M16/AR15 (trigger pack), and the M16 (barrel, fire control group) are clearly prevalent. The rifle also includes several features developed by Magpul, such as a quick-change barrel/trunnion system, adjustable gas regulator, non-reciprocating charging handle, and storage compartments located in the stock and grip. Just prior to the deal with Bushmaster, Magpul made additional changes to their design—the most obvious of these is the relocation of the ambidextrous operating handle to a forward position (somewhat similar to the Heckler & Koch G3 and Heckler & Koch MP5 series of weapons). Experts from Magpul Industries have on several occasions mentioned that depending on the barrel length of the weapon, the rate of fire is estimated to be in the range of 600-800 rpm (this is an estimate; specifics have not yet been verified).
            Bushmaster Firearms, with the help of Remington Arms (a sister company in the Freedom Group, Inc portfolio that includes Bushmaster, Remington, Marlin, and DPMS Panther Arms brands) has also made some design changes based on extensive environmental and functional testing specifically to meet the emerging requirements of the US military in both the carbine and subcompact weapon versions of the ACR family. It is expected that the rifle will be offered to military customers in 5.56mm NATO, 6.8mm Remington SPC, and 6.5 Grendel with the same lower and the user just having to switch out the barrel, bolt face, and magazine to change calibers. It is also expected that the ACR will have barrel length options of 10.5″, 14.5″, 16″ (commercial), and 18″. The official name of the rifle for military use will be called the Remington ACR.
              The magazine conceived for the 5.56 mm version of the ACR rifle is called the PMag, a high-impact, 30-round polymer magazine claimed by Magpul to be significantly more resistant to wear, shock, and harsh environments than other counterparts on the market. The PMag is STANAG 4179-compatible, as it will readily fit any STANAG magazine firearm, including the M16 rifle family. The Bushmaster ACR's modular construction even allows the user to fire the 7.62x39mm round with an alternate barrel.

Design 
           The original Magpul Masada design represents an amalgamation of several recent rifle designs, incorporating what is considered by its designers to be the best features of each in a single, lightweight, modular rifle platform.  Design features from the Armalite AR-18 (short-stroke gas system), the FN SCAR (upper receiver, charging handle location), the Heckler & Koch G36/XM8 (liberal use of polymer components), the M16/AR15 (trigger pack), and the M16 (barrel, fire control group) are clearly prevalent. The rifle also includes several features developed by Magpul, such as a quick-change barrel/trunnion system, adjustable gas regulator, non-reciprocating charging handle, and storage compartments located in the stock and grip. Just prior to the deal with Bushmaster, Magpul made additional changes to their design—the most obvious of these is the relocation of the ambidextrous operating handle to a forward position (somewhat similar to the Heckler & Koch G3 and Heckler & Koch MP5 series of weapons). Experts from Magpul Industries have on several occasions mentioned that depending on the barrel length of the weapon, the rate of fire is estimated to be in the range of 600-800 rpm (this is an estimate; specifics have not yet been verified).
 
             Bushmaster Firearms, with the help of Remington Arms (a sister company in the Freedom Group, Inc portfolio that includes Bushmaster, Remington, Marlin, and DPMS Panther Arms brands) has also made some design changes based on extensive environmental and functional testing specifically to meet the emerging requirements of the US military in both the carbine and subcompact weapon versions of the ACR family. It is expected that the rifle will be offered to military customers in 5.56mm NATO, 6.8mm Remington SPC, and 6.5 Grendel with the same lower and the user just having to switch out the barrel, bolt face, and magazine to change calibers. It is also expected that the ACR will have barrel length options of 10.5″, 14.5″, 16″ (commercial), and 18″. The official name of the rifle for military use will be called the Remington ACR.

         The magazine conceived for the 5.56 mm version of the ACR rifle is called the PMag, a high-impact, 30-round polymer magazine claimed by Magpul to be significantly more resistant to wear, shock, and harsh environments than other counterparts on the market. The PMag is STANAG 4179-compatible, as it will readily fit any STANAG magazine firearm, including the M16 rifle family. The Bushmaster ACR's modular construction even allows the user to fire the 7.62x39mm round with an alternate barrel.

Availability
          The ACR is currently slated to be available in third-quarter 2009 for military and government customers and fourth-quarter 2009 for a small amount of commercial customers. The ACR will be available in greater quantity (tens of thousands) in the commercial marketplace in 2010[citation needed]. It is anticipated that the rifle will have suggested retail price starting at $1,500 with semi-automatic versions available to the commercial market, and selective-fire versions available for military and law enforcement under the Remington name.