I've always used 115 gr. or 125 gr. FMJ rounds in my P1. I've read that there had been instances of slides developing cracks, but I believe that was because of use of very hot cartridges in the +P range, and because of very heavy usage. I believe if you use standard loads, just shoot occasionally, and are not on an intense shooting schedule like IPSC practice, your gun should be OK. After all, it was built for that.