Smyth Busters: Can You Mix & Match Bolt-Carrier Groups?
This video addresses the common question of whether AR-15 bolt-carrier groups (BCGs) can be mixed and matched. The hosts explain that due to standardized manufacturing, most BCGs will fit an AR-15. However, they emphasize the critical importance of checking headspace using a NO-GO gauge after swapping a BCG. They caution that even if a spare BCG fits initially, significant barrel extension wear from prolonged use with another BCG can alter headspace, requiring re-evaluation. The video debunks the myth that mixing BCGs is always problematic, provided proper headspace checks are performed.








