Every magazine has passed the U.S. military?s drop test and survived a few tests of our own. We?ve driven over them with full-sized trucks and dropped them from 4 feet onto concrete. The magazines never jammed. With regular maintenance they?ll last a lifetime. Magazine bodies followers butt-plates and feeding springs are manufactured by Thermold in the U.S.A.20-round nylon magazine for M-14/M1A-7.62x51 .308 caliber