So, I have a barrel cutoff in 35 cal from shortening a rifle. perfect "pistol length barrel"
Couldn't I chuck it in the lathe and cut the external profile to fit into the 20 ga chamber of my handi rifle slug gun? Or maybe my 12ga smoothbore? Then chamber it in 357 max. or even just 38 special, doesn't matter much. Add a couple o-ring grooves for "self centering" and snap on a couple Viton O-rings as a friction fit.
It would end up being like one of those shotgun chamber converters, just 2-3 times longer, since the muzzle would be resting in the actual barrel, not just a 3" or 3.5" insert.
No reason I can't do this and end up with a safe product, is there?