AR- 18 is a pneumatic firing modulated assault rifle equipped with ammunition magazine, which can fire 5.56×45 mm NATO standard ammunition. AR- 18 was designed by Amarette in 1963 on the basis of improving AR- 15. Although AR- 18 was not used as a standard rifle in any country, it influenced many later weapons, such as SA80 in Britain, SAR-80 and SR-88 in Singapore and HK G36 series in Germany. AR- 18 is also famous for its use in Northern Ireland, and it is nicknamed "Widow Maker".
Historical background?
1957 introduced the M 14 with the caliber of 7.62×5 1 mm, and the US Army Command (CONARC) began to carry out the derivative research of small caliber high-speed (SCHV) rifles: the SALVO project. Amaret and Winchester Raptors were asked to propose a prototype gun that fired a 5.56 mm high-rate rifle. The AR- 15 proposed by Amarette is a reduced version of 7.62mm AR- 10. Its competitor from Winchester is the prototype of the carbine designed by William Carbone.
M 16？
During the long-term test of AR- 15 by the US military, Fairchild, the owner of Amarette, gave up this design and sold the production right of AR- 15 to Colt. Fairchild Semiconductor also separated Amarette from an independent company, and allowed new business owners to purchase all the company's designs except AR- 10 and AR- 15. When the US military finally chose AR- 15 (named M 16), Amarette could not profit from it.
AR- 16 and AR- 18?
After Fairchild sold the designs of AR- 10 and AR- 15, Amarette could no longer use the direct jet pneumatic system on rifles. So Eugene stoner began to design short-stroke piston-driven rifles. In AR- 10 and AR- 15, the structure forged from aluminum is changed to be made of steel by stamping, which makes the new design easier to produce. Stoner still uses 7.62 × 5 1 mm ammunition for AR- 16 because the research on small-caliber high-speed rifles has not been recognized. Stoner left the company when Amarette reorganized. The U.S. military later decided to use the 5.56 mm AR- 15, and Amarette began to look for a design that could rival the AR- 15. Due to stoner's departure, the task of reducing the AR- 16 caliber was handed over to Amarette's new chief designer: Arthur Miller. The final design is named AR- 18. Arthur miller applied for a patent for this rifle at 1969.
Design?
The structure of the AR- 18 rifle is really different from the traditional AR- 15/M- 16 series rifles. Although AR- 18 rifle is also an improved gas transmission operation from SVT-40 semi-automatic rifle, it uses gas cylinders to receive gas, and then pushes the connecting rod to push the bolt backward to unlock and retreat the bolt. In other words, its structure is similar to that of M- 14 rifle, except that the handle and piston connecting rod are not an assembly. The magazine is similar to the magazine of M- 16 rifle, but the lug on one side of the magazine is worn off and the groove is newly formed on the other side, so the two magazines cannot be used together. The re-entry spring rod assembly is designed according to the double re-entry spring rod of M-3 submachine gun, and is installed behind the gun body to fix the upper guard wood.
The advantage of this structure of short-stroke piston is that it can delay or partially avoid the serious carbon deposition caused by the use of ammunition with low price but poor composition when shooting and burning, and it is not easy to accelerate the evaporation of lubricating oil of bolt assembly due to high heat, thus maintaining the due lubrication effect. The well-known AR- 15/M- 16 series rifles (including M4 carbine series) all use gas direct injection. A thin stainless steel tube sends high-pressure gas back to the receiving nozzle on the bolt base, and then pushes the bolt to recoil. However, in this link, the composition of ammunition will be bad, such as the receiving nozzle, the locking ear of the bolt machine and the muzzle of the magazine. When an average of 6,000 rounds are sent to 8,000 rounds (20 rounds are about 300~400 rounds), the bolt will malfunction and get stuck. If this happens when the enemy is surrounded or fighting fiercely, it will be embarrassing.
Production?
The design of AR- 16 of Amarette has never broken through the prototype stage. However, AR- 18 has been produced in small batches and tested to replace AR- 15. However, the defects of the AR- 15/M 16 rifle have been gradually improved through constant revision, and the US military is not interested in buying another 5.56 mm rifle.
Different from AR- 15/M 16, AR- 18 has not been greatly developed and has not been widely adopted by any army. AR- 18 is not because of any big defects in its basic design, but because Amarette lacks marketing ability. 1968, arthur miller left Amato because he was dissatisfied with the way Amato sold AR- 18.
The semi-automatic version of AR- 18 is named AR- 180, which is produced by Costa Mesa Factory in Amaret from 1969 to 1972. The AR- 180 of Costa Mesa is the first military semi-automatic rifle, which is widely used in the United States. Toyota Industries of Japan continued to produce AR- 18/AR- 180 from 1972 to 1974, but the Japanese government finally banned the production. Finally, British Stirling Armament Company continued to produce AR- 18/AR- 180 from 1976 to the mid-1980s.
Later, Amarette sold the manufacturing rights of AR- 18 to Singapore CIS Company, which later derived products such as SR-88 and SAR-80.
BRN- 180？
Brownells USA exhibited its BRN- 180 case set at the SHOT Show in 20 19. BRN- 180 is a modern design of AR- 180, the cavity is changed to 223 Wylde, the wood guard board is changed to M-LOK, and the top MIL-STD- 19 13 guide rail is added. The piston completely conforms to the size of AR- 180. The size of the upper shell has been modified to fit on the lower shell of AR- 15. Because of the design of AR- 180 bolt, the buffer is saved, so BRN- 180 can shoot without folding or even butt stock.
BRN- 180 includes standard BRN- 180 and short tube BRN- 180, standard BRN- 180 and short tube BRN- 180. Due to the use of AR- 15 magazine, BRN- 180 can use general AR- 15 magazine instead of special magazine like AR- 18.
Brownells introduced BRN- 180 casing running at the SHOT Show in 2020, which is divided into forged version BRN- 180 with the appearance of AR- 18 magazine well and square blank version BRN-180 with the appearance of ordinary AR- 15 magazine well. Except for the BRN- 180 upper shell, this lower shell is expected to correspond to the AR- 15 upper shell without buffer tube, such as MCX and 22LR caliber AR- 15.
In August, 2020, Brownells introduced BRN- 180 Gen2, which was improved to be equipped with all adjustable air guide seats of BRN- 180S, and changed the way of dismounting protective wood. At the same time, the BRN- 180S of 300 BLK is also introduced.