Allyyoopper I think its 45 or bigger, But this would be the same size bullet that you use in a 45 cal ML . Not sure but I am gonna look it up. Ididnt do any swabbing or cleaning at the range.. The breach plug looked spotless my first 16 or so shots, Then it dirtier after that. Next time at the range Im gonna start with the mmp sabots & .40 cal Gold dots. I shot those after 20 or so shots with the XTPs & SSTs. I wanna see how they do from a clean barrel or a barrel with 3 shots trhu it & so on. I havnt cleand the gun yet. I LL clean it later tonight.. I know barrels heat up . I guess I figured it would take more than 2 or 3 shots. Lesson learned there. Good day at the range all together. Gonna be a couple weeks before I get back to the range though