The USP f and c, along with the HK45 are all able to fire this round without a problem. I've only put a box of 50 through the mix of my different models, by they are able to handle it. Now if I were shooting it all the time (which is completely un-necessary), I would upgrade the springs to some a little stiffer. They work just fine for the short term though.So, you are saying an H&K USP is already capable of firing this round??? What mods did you do to yours?????