See if numrich arms has a firing pin for a crescent arms single shot break open .410 shotgun...
Odds are it will fit - or can be made to fit by somebody with some mechanical skill.
Maybe as a last resort option - a shot in the dark
What other dungeon is so dark as ones own heart, what jailer so inexorable as ones own mind.
Nothing gold can stay. Nature's first green is gold. Her hardest hue to hold. Her early leafs flower. But only so an hour. Than leaf subsides to leaf. So eden sank to grief. So dawn goes down today. Nothing gold can stay. (Robert Frost)