Mine locks in on 20 and 30 Pmags, Lancer L5 30s, USGI 30s, and the Surefire 60. Haven't tried to rip them out, but if you wiggle them, they don't come out. Test fired them all, and they stay in place when firing, and don't come out. Didn't honestly shoot the full Surefire 60, but it was fully loaded when I started with it - removed it before I burned through 60 expensive-and-hard-to-find rounds... <laughs> The Pmag 20 is the best, all around, IMHO.