If you can't shoot a shotgun, the .410 is an abomination. On the subject at hand, a 12 gauge shell shot in a .775 ten gauge bore should perform just fine, since many modern (and many antique) twelve gauge barrels are bored at .750 or better. I have not experienced any of these off sound reports in 12 gauge shells fired in Chambermates. On the other hand, I don't use any slow burning powders in 12 gauge target loads. Such loads, especially when fired in ten gauge bores, should be loaded with fast powders like Red Dot and 700X to keep the pressure and the sound up to specs. I hope my friend Sam benefits from my comments.
