I have a Hi Power that is leading the barrel with Lyman 120 gr,truncated cone bullets. I am running them thru a .358 sizer but usually it just touches the high spots. My S&w 9mm's lead very little if at all with this bullet. I havent slugged the bores yet but am thinking the S&W's may have a smaller bore.Anyway does anybody have an idea what the current production hi powers groove diameter run?