My fun with 'single shots' is and has been limited to Stevens "Favorite" and "Model 44" types with a pending project or two on a M1 Carbine receivewr to be a Straight pull single shot rifle of 23 inch barrel length. By blanking off the gas ports (not drilling them) in the new barrel and leaving off the gas cylinder block, i am able to make a 1.1" diameter b;lank barrel work.
two are pending: a .45 Win Mag version and a .30 Carbine one.
Both arer at my gunsmith's waiting for him to get around to them.
The Favorites are for experiments wit .25ACP conversions and wildcats in CF mostly. The Model 44 action is for my longer bodied .25 Wi;dcats all of which are using .250"-.251" diameter bullets, both Lead and Jacketed types.
I also have both a revolver and a semi Auto pistol converted to .25ACP and the revolver is set up with interchangable cylinders for other .25 CAL cartridges.
Chev. William