Not wanting to make anything that is not legal. I have a need to control pests in a barn and shotguns make to much damage. animals a little to fast for a pellet gun. the rifling in my 22lr barrel makes the pattern pretty thin at the distances I need to shot. Would it be legal to build a smooth bore insert for a 357/44/45 caliber barrel similar to the inserts used to reduce the bore size on shotguns. this would allow shooting 22 shot cartridges with the rimfire firing pin in the gun. ejecting shell with a rod down the bore. the minimum length for a shotgun is 18". does the smooth bore and shot cartridges make it a shotgun? There were some smooth bore 22 gallery rifles that may have been under 18". I have always wondered if almost straight grooves, minimal twist makes it legal. there is a double barrel 45/410 pistol that has 1:48 twist. Not aware of any donor 22 barrels that would be that slow.
Looking for possibilities.
Looking for possibilities.