GETTING MY CMMG MK57 TO WORK

With a lot of the distinctive projectiles I'd handy — most notably the massive, fifty five grain subsonic rounds from Detroit Ammo Co (not pictured) — the bullet-shaped grooves from the front with the FN magazine didn’t Perform properly.The two ProMags I employed worked flawlessly, plus the factory 5-7 mag I'd didn't. I’ll acknowledge my co