I was wondering this while loading up some .40 SW the other day. This spurred an impromtu unscientific experiment to collect some numbers and justify why I bought it and use it. I'm not gonna bore you with the excuses I used to convince myself why I got it. Trust me I've used lesser logical ideas to waste more money (lots more money) than I did on the Bulge Buster..........we all have. Nor am I gonna bore you with the 2 pages of big words Miriam Webster could provide and my thoughts about this fact finding mission. And, no I won't be doing this for my 10MM brass either. So for now "Just the facts ma'am". Brass: 2x fired Winchester Gun: Glock 23 gen 2 Dies: RCBS carbide and Lee Bulge Buster Calipers: Starret dial calipers Press: RCBS Rock Chucker Supreme For the time wasted on this I could've reloaded a couple hundred rounds, shot them and reloaded again. If this helps in your decision to buy or not to buy great.