+p ammunition is a higher velocity ammo. Usually self defense rounds are +p for added penetration. Most manufacturers recommend limited use of +p ammo, since it can wear parts out quicker than standard velocity ammo but unless you're shooting thousands of rounds I doubt you'll ever notice a difference vs standard velocity ammo. Then you have +p+ ammo Wich very few if any manufacturers will say it's ok to shoot out of their firearms cause there's no Saami spec, meaning there's no limit to how much pressure/velocity is to much. Most modern firearms can handle +p ammunition but always make sure the manufacturer says it's ok to use cause if not it can cause injury or issues with your firearm. Hope this helps.

Ammunition rated +P generates a chamber pressure higher than the cartridge’s published standard, but the level is less than those produced when proof rounds initially torture test a firearm. Increased bullet velocity is the result—an advantage for some self-defense handguns—but not all guns can safely run the hotter loads.

It is deffensive ammo that is loaded a little hotter (faster, more ft lbs of energy) to give better penetration, and slightly better expansion of hollow points.

Gary, +P is ammunition with extra powder making it shoot with higher velocity/energy. +P is normally around 50 to 75 fps faster than standard loads depending on the manufacturer. +P+ adds even more powder for even higher velocity/energy. You have to make sure the firearm is rated for it as it also produces extra pressure when firing. Cheers and stay safe!.

Gary, +P rounds have been loaded to higher internal pressures, so there is more gun powder packed into the same space, as opposed to extending the cartridge to make room for powder. This creates a more forceful explosion during ignition. +P is most often used for self-defense purposes. Because of the increase in speed and energy, it can deliver greater stopping power, which makes it ideal for personal protection. It is rarely used for any other purpose, although it may be used for hunting. Have a great day!