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.

Features :

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