Just got a JP gmr-15, and put 875rnds through it in the past two weeks. I feed it FM 124, FM 135, FM 147, Stand-1 147 chubbies, Winchester 124 nato, Blazer aluminum 115, lawman 115, and cap arms 147 subsonic. Not a single hiccup with any of the ammo. I felt like the FM 135 had the least...