I recently completed a build on a CMMG "blem" lower. Some of the pins were a pain in the butt to install, and I ended up having to "squeeze" down a couple roll pins to get them to fit. All is well with the lower parts kit installation, however, some mags don't drop free. P-mags are a no-go and certain brands of metal mags don't drop free. Any cures to this issue that any of you have had success with? It was an inexpensive lower that I don't plan on returning, but I am disappointed that CMMG sent out lowers that are not dimensionally correct.
File? Sand paper? Any insight would be helpful...