I have a Px4 in .40. I really like the gun except for the fact that it trigger slaps. It only seems to do it with certain ammo though, but when it does I sometimes can't even run through an entire mag because it straight up hurts. My buddy has a Px4 in 9 and it is more tame then mine. With that being said, I think the Px4 handles the "snappy" .40 cal just fine. If you want to shoot one before you buy, PM me.