New to this forum and have always been a Kimber guy. My question is When ordering a KKM or Storm Lake conversion barrels, 40 to 9. What is the difference between that and a standard 9mm barrel. Does the 40 slide have a larger inside diameter for the 40 barrel, and therefore the 9mm conversion barrel have a larger O.D. so that it has the correct tolerance for the slide. I can't find any dimensions or information to tell the difference. Thanks in advance for any clarification that you guys can offer. I'm going to purchase an M&P40L C.O.R.E center ported.