The Gibbz Arms G4 Side Charging Upper Receiver is a non-reciprocating upper receiver with a detent to keep the charging handle forward during operation, and uses all mil-spec and most custom bolt carriers without modification. The Gibbz Arms G4 Side Charging Upper Receiver features an enlarged ejection port and will work with AR-15 calibers from 22LR to 50 Beowulf. Beveled Ejection Port Full 15 Slot Picatinny Rail Bolt carrier door in the rear to allow for easy bolt carrier removal and gasses in during operation (important for suppressed fire). Compatible with Mil-Spec and most other lowers receivers Enhanced cam-pin optimized for side charge upper with Mel Mfg: Gibbz Arms
