Overpressure Ammo (+P Ammo)

Overpressure ammo, designated as +P, is a cartridge that is loaded with a higher energy content of powder and results in higher internal pressure as compared to the standard load. The standard load for 9mm ammo designates a maximum pressure of 35,000 psi. The +P load is designated 10% higher at 38,500 psi.

Dimensions of the +P cartridge are exactly the same as standard ammo, the only difference is in the powder and in the '+P' stamped on the base of the cartridge. The +P rounds are sometimes referred to as ‘hotter loads.’ Be aware that not all guns are rated for +P ammo. Unless the firearm is marked as +P rated or it is stated explicitly in the gun's manual, +P ammo should not be used. Selecting +P creates more recoil, higher velocity, and incrementally more stopping power. It also moves in the direction of potentially causing more malfunctions with automatically chambering and extracting rounds. Some guns suffer from reliability issues with +P while others handle it with no problems.

There is a designation of overpressure ammo that is even more extreme, named +P+. This is used to classify ammo that goes beyond the +P maximum of 38,500 psi. There is no industry standard for the upper limit on +P+. It's only offered by a few ammo manufacturers and their cartridges operate just slightly above the +P range.

The majority of people stick with standard 9mm ammo and this is by far the largest share of the market in comparison to +P and +P+ cartridges.

Next Topic: Ammo Shelf Life & Storage