+P Ammunition Information
Most shooters know the "P" in the +P designation on a cartridge headstamp stands for pressure and indicates that the cartridge is loaded to higher chamber pressures and thus higher velocities. But many are confused as to exactly how much pressure is added and how safe these high-performance
All the major American ammo manufacturers are SAAMI members, and most smaller outfits also abide by SAAMI guidelines, but I have seen ammo from one or two small manufacturers offered in calibers such as .40 S&W and .357 Magnum with the +P designation.
Since SAAMI does not specify +P ratings for these cartridges there are only two possible explanations. Either the ammo is loaded to higher pressures than SAAMI deems safe or the +P designation is just marketing hype. Be aware, all comments in this article regarding the safety of using +P ammunition are related to SAAMI-sanctioned +P loads only.