Post I reviewed about bolt modification:
Fitting a CMMG bolt carrier to a Glock AR Lower
My adventure to build the perfect 9mm AR has taken a few twists and turns but I now have a Glock 9mm AR that runs great. I ran 100+ rounds through it last night without a single issue.
I started with a mag block (for Colt mags) in one of my lowers that ran pretty well. I already have a CMMG 9mm AR so I'm used to the Colt mags and how much they suck. Ok, the loader makes them tolerable but I hate relying on a loader and already have a ton of Glock 17 mags so I wanted to go Glock with the lower.
I found a QC10 lower (Thank you Baltimore's Best Pawn!) but spent the last week trying to find the correct BCG to run with the Glock mags. I did find a place that would cut my CMMG 9mm BCG if I shipped it to them but I'm impatient and the CMMG bolt was a spare so out comes the Dremel.
The issue is the bottom of the CMMG bolt carrier is made to fit the Colt mag feed lips. The Colt mag feed lips are wider than the Glock so the CMMG bolt carrier will not fit through the top of the Glock mag. I figured I'd have to remove a little material from both sides of the bottom of the bolt carrier but ended up only having to gind on one side. I tried to buff it a little to smooth it some but this bolt carrier is not going to win any beauty contests!