I shoot winchester BRIs 2 3/4 out of super X full rifled barreled. It shot 4inc 5 shot groups at 100 no problem . I shot Rem. Copper solids 10inc at 50yds ! At 100 never hit the target ! So like with rifles slug gun's have there preference to what they like to shoot . As far as shooting a fouler befor testing . I don't know about you but I very much want to know where that first shot is going to hit out of a clean barrel ! After all your first shot at a deer is going to be out of a clean barrel ? These are shotguns not bench rest rifles .