Bear Creek Arsenal BC15 .458 SOCOM 16in Upper Receiver Heavy Carbine .936 1-14 5/8x32 Flash Hide Parkerized. 458 SOCOM upper is compatible with any mil-spec AR-15 lower. Magazine not included. Specifications for Bear Creek Arsenal BC-15 .458 SOCOM 16in Upper Receiver: Manufacturer: Bear Creek Arsenal Caliber: .458 SOCOM Barrel Length: 16 in Barrel Profile: Heavy Gas System Length: Carbine Length Barrel Twist Rate: 1-14 Threads per Inch: 5/8x32 Muzzle Device: Flash Hider Finish: Parkerized Gun Model: AR-15 Handguard Length: 15 in Gun Rail: M-LOK Gun Make: AR Platform Weight: 5.5 lb Flutes: No Package Contents: Bear Creek Arsenal BC-15 .458 SOCOM 16in Upper Receiver What firearm models does the manufacturer say Bear Creek Arsenal BC-15 .458 SOCOM 16in Upper Receiver is compatible with? The manufacturer suggests that Bear Creek Arsenal BC-15 .458 SOCOM 16in Upper Receiver is compatible with AR-15Bear Creek Arsenal UAFC4053458CHB1611493615TNGSR: BC15 .458 SOCOM 16in Upper Receiver Heavy Carbine .936 1-14 5/8x32 Flash Hide Parkerized