I’ve limited of tried to make critter gun/cartridge for use when bushhoghing the pastures. The concept seem vialble in result, it is not sustanable. It takes too long to draw the pistol and aim at the target. And even then the target is out of effective range when you figure the height of the shooter sitting on the tractor.
Anyway, as a kit gun for short range use, the Bond Arms derringer should work well for less than animated targets.