Haus20;
I'm not familar with your particular shotgun, but I have a much older Stevens #59A that I've shot slugs through many times with no ill effects. This gun is probably closer to 50 years old. It's a .410 fixed choke (modified).
With screw in chokes, as your gun has, I'd use the most open choke tube you have. Improved Cylinder would my guess . You probably have chokes marked Imp Cyl, Mod, & Full.
HTH
Dave