512 is AKA the .22/45, which has a mag release where God and JMB intended they be
Take it down and clean it,,,,pay particular attention to the inside of the grip area,,,crud can fall down into there and gum things up badly. Take apart the magazine(s) and scrub it (them) out also,,,pay particular attention to the front where the bullet rubs against the magazine. .22 ammuntion usually uses a "waxy" type lube that builds up on the front of the magazine.
If it still does it after it's properly cleaned and lubed,,,either:
- quit using Stingers in it - using them is pretty much a waste of money since you pay way more for what you get in return out of most pistols, for most uses.
- try loading either a standard velocity or a high velocity round on the bottom and 9 Stingers on top of it.