The AR-57 also known as the AR Five Seven , is an upper receiver for the AR-15/M16 rifle lower receiver, firing 5.7×28mm rounds from standard 5.7x28mm magazines. It was designed by AR57 LLC and is currently produced by AR57 of Kent, Washington, USA. The AR-57 PDW Upper is a new design on AR-15/M16 rifles, blending the AR-15/M16 lower with a lightweight, monolithic upper receiver system chambered in FN 5.7×28mm. This model is also sold as a complete rifle, supplied with two 50-round P90 magazines. The magazines mount horizontally on top of the front handguard, with brass ejecting through the magazine well. Hollow AR-15 magazines can be used to catch spent casings.
Unlike the standard AR-15 configuration which uses a gas-tube system, the AR-57 cycles via straight blowback. A full auto version exists marketed as a competitor to the P90 and other personal defense weapons.
AR57 Review 5.7x28
AR57 Instruction video
Weapontype: Semi-automatic carbine Personal defense weapon
Manufacturer: AR57 LLC
Operation: straight blowback
Cartridge: FN 5.7×28mm
Weight: 7.45 lb (3.4 kg) (AR-57 PDW)
Length: 30 in (762.0 mm) (AR-57 PDW)
Barrel: 16 in (406.4 mm) (AR-57 PDW)
Rifling: Barrel Twist rate 1:8 in
Magazine Capacity: 50-round
Feed system: FN P90 detachable box magazines
In Production: 2008 - Present
Sights: 4 M1913 Picatinny rails for optics and sights
