CMMG 5" 4140CM SBN 5.7x28mm Barrel and Bolt Carrier Group Kit for AR-15 Builds

The 5" 5.7x28mm Barrel and Bolt Carrier Group Kit is designed for building an AR-platform firearm chambered in 5.7x28mm using a radial delayed blowback operating system. The system helps reduce bolt carrier group weight and felt recoil compared to traditional direct blowback designs. This kit is intended for assembly into a mil-spec AR-15 upper receiver and is compatible with either a Mk57 lower receiver or a standard AR-15 lower receiver when used with compatible 5.7 AR conversion magazines. 

Product Features

• Includes barrel and bolt carrier group kit. 
• Chambered for 5.7x28mm. 
• 5-inch barrel length. 
• Utilizes a radial delayed blowback operating system. 
• Designed for use with mil-spec AR-15 upper receivers. 
• Compatible with Mk57 lower receivers or standard AR-15 lower receivers when used with 5.7 AR conversion magazines. 
• Lifetime Quality Guarantee.