CMMG BBL 300BLK 16.1" MR 4140CM SBN

Perfect for building your custom AR15 upper group. Comes with properly installed M4 barrel extension. All barrel sub-assemblies are properly head spaced.

• 1:7 Twist 4140 Chrome moly
• 5/8X24 thread pitch
• Multi Role profile
• Carbine length gas port .750" gas block Journal, 300 Blackout chamber