The galling of the bottom of the on-off assembly could make the on-off pin stick, but shouldn't make it leak. The orings that cause the leak are on the inside top of the bottom section and on the outside bottom. Both of these orings shouldn't be affected by galling. There could be debris from the pounding though. Try replacing both lower on-off orings. If the hole is smashed in, try reaming it out at the bottom only, to remove the burrs.
Except for the Automag in front, its usually the man behind the equipment that counts.