GETTING MY CMMG MK57 TO WORK

With many of the unique projectiles I had handy — most notably the massive, 55 grain subsonic rounds from Detroit Ammo Co (not pictured) — the bullet-formed grooves in the entrance of the FN magazine didn’t Participate in nicely.The two ProMags I applied labored flawlessly, and also the factory Five-7 mag I'd did not. I’ll confess my normal