I guess the 30 round mags are luck of the draw. In '54/'55 during occupation duty in Cold Rear, I'd occasionally "liberate" a 600-round canister of ammo and go to the beach at Inchon with my M2. Spray and pray at seagulls and sea shells and all that juvenile stuff that a 20-year-old will do. Never had any problems with the mags on full auto.