working on a loaded gun. I remember Kase and that Browning rifle! It sure could have been bad. It discharged from beating a rod down the muzzle. Actually detonated the primer from powder crushing the anvil in reverse?! I think that was the thought.
Rimfire is an added caution with that crushable rim full of compound. You can mash it flat in a vice, but don't "hit" it. I'd very gently polish the chambers with "Flitz" and call it good. Common lighter fluid on a Q-tip is a good .22 chamber cleaner.