57 Center Ar-15/M16 Ar57 Upper Receiver
Converts Any AR-15 To Shoot 5.7 x 28mm
Complete upper receiver lets you shoot economical, gentle-recoiling 5.7 x 28mm ammunition in your AR. The innovative, low-profile 50-round magazine (sold separately) is positioned conveniently above the barrel for optimum weight distribution. Spent cases are ejected straight down through the magwell to avoid striking other shooters and for easy range cleanup. Simple, reliable blowback operation with a free-sliding bolt that's the only moving part means there's no gas system to foul or clog with carbon. Ultra-rigid, monolithic receiver/handguard rail is machined from a single block of aluminum, with nearly 3 feet of Picatinny rail space for mounting optics and other accessories Mfg: 57 Center SPECS: 25" (63.5cm) O.A.L. 4 lbs, 9 oz. (2.1kg) weight. Receiver/Handguard 7075 T6 aluminum, hardcoat anodized, matte black. Barrel - 4140 chrome-moly steel, Parkerized, matte black. 16" (40.4cm) long, 1-8.5" twist.