I am no expert but I don't think you'll break your S9 with +p+ ammo but you are certainly shortening its life span (or at least major parts) if you shoot lots of them ... however, your wallet will likely break first! :lol:got hydra shok jhp 124 gr +p+ for my s9 as a defense round with the occasional range trip. am i messing up?
Keep in mind that Steyr wundernines are "scaled-down .40's" ... also many foreign 9's are built to handle NATO-spec ammo which is much higher than the SAAMI-spec ammo used here in the States.
Another issue to consider, however, is that not all +p+ ammo is created equal. All you know is that they are above +p pressure levels ... you just don't know HOW MUCH over it is though. Hope this helps!