I asked this question about my USP45f... Word was, dont dry fire it with out a snap cap as it can ream out your firing pin hole or the stress can cause your firing pin to break.
Whatever, I thought.
Just to be safe I bought a snap cap and used it all the time. In short order there was a little divot in the end of the snap cap which I ignored.
200 dry fires later CRACK! SPROING! Parts came flying out of my gun!!!
Sure enough the firing pin had broken and although it was replaced free of charge, it did lower my confidence level of the USP's invulnerability.
I still use a snap cap, but if I break another firing pin I am going to ask for a spare. Still makes me a little nervous. I am sure that I could have had a firing pin with a flaw in it but I have heard other people mention that they too know someone that htis has happened to.
Good Luck!
J.T.