[tony k]

One possible cause of the "double-tap" is the replacement firing pin. If it is even slightly out-of-spec in height or width (or if the firing pin spring is at all weakened by age), the firing pin may be occasionally "binding" in the bolt slot and not fully retracting after a shot is fired.

If the firing pin hangs up in the forward (firing) position, it can create a "slam-fire" when the bolt comes forward, picks up another round and feeds it into the chamber -- the firing pin pinches the rim, and ignites the round, the instant the cartridge is fully chambered. It fires without anyone even touching the trigger.

The fix would be to check the new firing pin and polish/file it everywhere it could bind. Also check for a broken or compressed firing pin spring, and make sure the firing-pin "channel" in the bolt is absolutely clean.

HTH.

 

[tony k]

This makes me wonder...Has anyone ever build a Full auto Mossy .22?

I saw one a few years ago -- a 152 that was registered with BATF as a machine gun and converted in the 1970's. The owner had located some 15-round magazines, which you needed because the rate-of-fire was so high (probably around 1,000 rpm, like most full-auto .22 rimfires) that it emptied a seven-round mag in less than a half-second.

I've been involved in (legal) full-auto shooting for decades, and that's the only full-auto Mossy I have seen or even heard of.