Radical Firearms Complete Upper Assembly 16in 5.56 SOCOM 1/7 Twist 15in RPR M-LOK Zero Impulse Black CFU16-5.56SOC-15RPR-ZS. 56SOC-15RPR-ZS Specifications for Radical Firearms 16 in. 5.56 SOCOM Upper Assembly w/ Zero Impulse Brake: Manufacturer:...