For what it is worth: The only thing that really matters is what cartridge works best in your pistol. The ammo must fit into the magazine properly. Feeding, firing, extraction, ejection must all be 100%. A final consideration, which I believe to be of utmost importance, is that the ammo must shoot to point of aim (this can be a real problem with pistols having fixed sights due to differing velocities, "barrel times", recoil impulses, etc, that can all cause significant differences).