My 9mm Shield has about 500 rounds thru it....one box of factory FMJ, the rest my 124 gr RN lead reloads. I do the same thing with my Shield that i do with my 1911's. When it's time to seat bullets and crimp i disassemble the gun and keep the barrel handy. I "plunk test" every 10 rounds or so to make sure they'll chamber( i use a single stage press and only have one 9mm). If i had more than one 9mm i'd use the barrel with tightest chamber. You may also benefit loading cast to seat bullets then crimp as opposed to seating and crimping in one operation.....Mike