I was recently at a range with my son, we were both using nearly new Ruger 10/22's and he had a missfeed. The round had started into the chamber and gotten stuck so tight that the bolt could not be pulled back easily. Keeping the muzzle pointed down range the bolt was finally jerked back hard enough that the extractor came off of the case rim and the bolt came back. The bolt was then released and we had a "Slam-Fire". I do not know for sure but I suspect the rifle was still out of battery when it fired, with a .22 this is not as catastrophic as it would have been on a centerfire rifle. My son had been using Winchester 555 that seemed to be giving him some trouble with misfeeds and failure to fire so we switched to some CCI he had and we had no more troubles with the rifle.
I do not think we followed the best process for clearing this rifle. Thinking about it, any action that causes the extractor to release from the cartridge would risk setting off a rimfire .22 and in this case releasing a bolt onto a cartridge that is stuck, crooked, halfway into the chamber runs the same risk. Should we have considered running a cleaning rod down the barrel to dislodge the round? There is a lot of risk there as well, particularly if the bolt is still in contact with the base of the round.
My 2 cents:
1. Rule #1.
2. Lock the bolt back.
3. Rule #1
4. Push a brass rod or wooden dowel to push the stuck round out (brass or wooden to protect the muzzle crown).
5. Be real careful.
aj