I experienced a strange malf with my Mk.III 22/45 yesterday.
Towards the end of the range session, the trigger began to behave oddly. The break was mushy, and the round didn't go off. I ran the bolt, and got the same thing. I ran the bolt twice more, emptying the mag, and the gun refused to discharge on either try; it felt as though the gun wasn't staying cocked, and the primers showed no marks, although something must've been happening to reset the trigger.
When I removed the magazine and reloaded to continue trying to diagnose it, the problem disappeared. I suspect the mag safety.
Who here has successfully disabled the infernal device by replacing lockwork parts with Mk.II bits?