You can shoot foster type rifled slugs. Their made to go through chokes. Steel shot doesn't have the give lead shot has. It can blow the end off your barrel, or yard it right off. I've seen that. The best thing you can do, is take it into a gunsmith, and he can ream it out to a modified choke. A mod is safe for all shot, but not saboted slugs. Never shoot a sabot slug out of anything other than a rifled choke or barrel.