New BCG [Archive] - Glock Talk


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09-18-2010, 11:12
I've got a BCM Auto BCG on order for my new NFA-legal LMT 10.5" upper going on my Bushmaster Patrolman lower. Since this upper didn't come with a BCG, what should I check when putting the BCG in? Is it "drop-in" ready?

09-18-2010, 11:44
Most are close enough but the headspace should be checked, as an example combining a LMT barrel that was setup for a LMT bolt might be tight when used with a CMT bolt because most CMT bolts have a .153" back of lug to bolt face dim and most LMT bolts have a .148" BOL to BF dim. If the BCM bolts are Microbest bolts like I believe they are it should have a .150 BOL to BF dim which is in the middle of the other 2. Most of the time mix and match works, sometimes it doesn't.

09-18-2010, 11:48
Thank you! Just what I was looking for.