The 1100 is a semi auto and one of the best ones made. You can shoot any shells you want but do not shoot slugs that are designed for a rifled barrel in a smooth bore barrel. Accuracy will suffer. Buckshot does not do well in a rifled barrel either. If you shoot the shells the barrel is designed for you will be pleased with that 1100. Slug barrels are usually cylinder but you can shoot full choke if that's all you have. For more research check out shotgunworld.com. Best site around for shotgunners.