The CMMG 55BA419 BOLT CARRIER GROUP is a Mil-Spec part made for the M16 in 5.56 caliber. This also works great for the AR-15 in .223/5.56! (M16 bolt carriers are Mil-spec and work with both full-auto and semi-auto rifles, including the M4, AR15, and M16!).
Pick the drop-in replacement and go for the 55BA419 Bolt Carrier Group.
- Complete BCG. All you need all-in
- Drop-in replacement - just switch and replace
- Manganese phosphate finish - protected to last
- Magnetic particle inspected - quality ensured!
Finish: Manganese phosphate, Black