Bought a M71 .22lr from Buds. Took off foney supressor. Accurate gun. Had to buy 2 magazines from Triple K cause original mag lips were beat to death and was unuseable. Useing standard or high velocity ammo half way through shooting the slide will lock back. Not always, but enough to not want to rely on gun as a life saver in a emergency. Gun looks like it was carried more than shot. Any suggestions on fixing this problem is greatly appreciated.