The AR57 Upper Receiver Assembly converts an AR-15 to shoot 5.7x28 FN ammunition. The unique upper design loads on top and accepts FN PS90 magazine (not included) and ejects downward through the AR-15 magwell. This upper is precision machined from a one piece aluminum forging. The integrated picatinny-style quad rail system allows attachment of various accessories. A parkerized chrome alloy bolt and full-floated barrel ensure reliability and accuracy. The teflon-infused hard coat anodized aluminum upper and rails guarantee durability for years of shooting enjoyment. The updated charging handle and magazine release of the Generation 2 allows for easy manipulation of the controls. New and improved lightening features, such as the fluted barrel, shave a pound of this receiver when compared to the Generation 1 upper assemblies. The top feed and bottom eject also help to make this upper fully functional for right or left handed users. A carbine style (3 1/2 inch) buffer is included, rifle length stocks require the AR57-A2 buffer (6 inch), which is sold separately.



Technical Information

Upper Receiver: A3 Flat-Top

Barrel Length: 16"

Barrel Contour: Fluted, heavy

Barrel Material: 4140 Chrome Moly Steel

Muzzle Thread Pattern: 1/2"-28

Chrome Lined: No

Barrel Finish: Parkerized

Twist Rate: 1 in 8.5"

Chamber: 5.7 x 28mm FN

M4 Feed Ramps: N/A

Muzzle Device: A2 Flash Hider

Gas System Length: Carbine

Gas Block Diameter: 0.750"

Handguard: Free-Float Quad Rail

Sights: None

Bolt Carrier Assembly Included: Yes

Bolt Carrier Type: N/A

Includes Single Rail Gas Block





Please Note: Installation of AR-15 upper assemblies with certain features including, but not limited to: flash hiders, bayonet lugs, and threaded muzzles may violate state and/or local laws.