U.S. company AAI (Aircraft Armament Industries) has been developing advanced systems of small arms for the U.S. Army since the mid 1950s, when one of the company's founders, Irwin Barr, suggested the idea of using the U.S. military swept feathered piercing ammunition for small arms. Such ammunition allows little in return and high flatness shooting at high destructive action through the use of light-feathered arrows made of high strength steel or tungsten, and having a high (more than 1200 m / s), the initial velocity. This theme was developed by AAI through a variety of programs, including SALVO («volley", 1952-1962 gg), SPIW (Special Purpose Infantry Weapon, 1962-1974 gg), FRS (Future Rifle System, 1969 - mid-1970s ), ACR (Advanced Combat Rifle, 1986-1989 gg).
Samples rifles program ACR
Companies AAI, HK, Steyr, Colt (top-down)
research program ACR (Advanced Combat Rifle - improved combat rifle) was developed by the U.S. Army during the second half of the 1980s in order to determine the possibility of increasing the combat effectiveness of individual small arms (machine) at least 2-fold compared with the M16A2 rifle. In this program, and competitive trials took basically four arms company - AAI and Colt (USA), Steyr (Austria) and Heckler und Koch (Germany), with its samples of the new assault rifle.
ACR company AAI, along with the Austrian firm Steyr also play the role of developers under arms ammunition with SPEL (high-speed, small-caliber flechettes). Initially the company focused on creating AAI weapons under caseless cartridge and two main types of ammunition for it - with the usual 5.56mm bullet weight 4.67 grams and an initial velocity of 880 m / s, and with an arrow piercing feathered caliber 4.32 mm, weighing 1.81 grams and the muzzle velocity of 1160 m / s. But later, due to modest success in developing such ammunition (in comparison with the German company Heckler-Koch) AAI company switched to weapons development under traditional cartridges with brass sleeve and high-speed subcaliber flechettes.
new cartridge with SPEL firm AAI has developed on the basis of the standard cartridge casings from 5,56 x45 mm NATO. Instead of the usual bullet it was feathered arrow from a high strength aluminum alloy, weighing 0.66 g, 42.4 length and 1.6 mm in diameter. Arrow was a plastic casing-pod that when departing from a barrel under pressure counter air divided into four radial segment, and she developed a boom initial velocity of about 1400 m / s. For this cartridge by AAI has developed a new assault rifle.
With ammunition used
Assault rifle (automatic) AAI ACR was based on the traditional automatic venting mechanism and a rotating bolt. In connection with the use of light piercing arrows in gas operated pallet assembly had to be moved into a zone of high pressure closer to the chamber, which eliminated the use of conventional rounds of 5.56mm NATO because of the danger of destruction mechanisms rifles higher pressure in the barrel.
By what size cartridge AAI staff were close dimensions 5.56mm NATO cartridge with the same sleeve, but fundamentally different characteristics of the pressure of powder gases in the barrel during firing to create weapons under this cartridge AAI engineers had to create a special shops capacity of 30 rounds are not compatible with M16 rifles from shops chambered for 5.56mm NATO, and allows you to charge them as "normal" ammo 5,56 x45 mm NATO.
Cartridge AAI ACR
body of weapons made of two plastic halves connected by pins - top consisting of receiver box with venting mechanism and barrel, and bottom consisting of a box of the trigger, the pistol grip and buttstock.
Barrel has a special muzzle device that acts as a muzzle brake, and the flame arrester unit reducing sound of a shot.
trigger mechanism provides firing single shots and bursts of arbitrary length. Lever fuse is located right above the trigger.
bolt handle is on the left arms over the gun, release of spent cartridges made right.
With the use of mechanical devices open
Sights nominally included optical sight Trijicon ACOG 4X, mounted on a special side bracket on the receiver. As a mechanical sighting devices use a fixed front sight on the barrel and adjustable rear sight backup (removable).
| Caliber, mm || 5.56 (1.6 ) x 45 |
| Length mm || 1016 |
| Weight empty, kg || 3.5 |
| store count. cartridges || 30 |
| Muzzle velocity, m / s || 1400 |
Overall ACR had a number of significant advantages - a small impact, high flatness of shooting and very little flight time arrows to the target, reducing the effects of errors in aiming for the remote and moving targets. Arrow Special cartridge AAI, used in the assault rifle, at a speed of 1400 m / s with a very high penetrating ability and good armor penetration, but its stopping power due to the small mass appeared relatively small.
Testing of cartridge-rifle gave very good results, but the military decided that the main requirements of the program «Advanced Combat Rifle» - fold increase combat effectiveness - ACR rifle company AAI has been reached, however, as the rest of the main contenders (Steyr, Heckler und Koch, Colt). Besides all the advantages of the new weapon does not pay the huge costs required for the translation of the U.S. Army (or any other) to an entirely new system of small arms. ACR program was closed and the rifle company AAI development so never received.