Understanding 9mm +P Ammunition

 First, let's start by answering the following: What is +p ammunition?

"+P ammunition", also known as overpressure ammunition, is ammo that's been loaded to a higher internal pressure than standard ammunition of the same caliber.

This increased pressure results in higher velocity and energy output, which can lead to improved performance in certain firearms and shooting situations.

However, +P ammunition should only be used in firearms rated for it, as it can put additional stress on the gun and potentially cause damage or malfunction.

*Always consult the firearm manufacturer's recommendations or with a qualified firearms expert before using +P ammo.

To fully understand what +P ammunition is, you must first understand how the manufacture of commercial ammunition is controlled.

An organization known as the Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI) establishes guidelines for ammunition production.

These guidelines stipulate the sizes and pressures of commercial ammunition.

Most major ammunition manufacturers follow SAAMI guidelines to ensure all their ammunition will function safely in all guns.

For example, this allows 9mm ammunition manufactured in 2020 to work perfectly in a 9mm handgun made in 1990 or vice versa.

The benefits of +P ammo depend on the specific cartridge and the firearm it is used in.

In general, +P ammo is loaded to a higher pressure than standard ammunition, resulting in a higher muzzle velocity and more energy upon impact.

This can result in improved terminal performance, deeper penetration, and better expansion in certain types of ammunition, such as hollow points.

However, the higher pressure also means more recoil, which can make the firearm more difficult to control and increase wear and tear on the gun over time.

9mm +P
This ammunition has a higher pressure and velocity than standard 9mm ammo, making it popular for self-defense.

.45 ACP +P
This ammo has a higher velocity and energy than standard .45 ACP ammo, making it an effective option for self-defense.

.38 Special +P
This ammo has a higher velocity and energy than standard .38 Special ammo, making it popular for self-defense and law enforcement use.

.357 Magnum +P
This ammo has a higher velocity and energy than standard .357 Magnum ammo, making it a popular choice for law enforcement and self-defense.

.40 S&W +P
This ammunition has a higher velocity and energy than standard .40 S&W ammo, making it an effective choice for self-defense.

.380 ACP +P
This ammunition has a higher velocity and energy than standard .380 ACP ammo, making it a popular choice for concealed carry and self-defense.

.38 Super +P
This ammunition has a higher velocity and energy than standard .38 Super ammo, making it popular for competition shooting and self-defense.

10mm Auto +P
This ammunition has a higher velocity and energy than standard 10mm Auto ammo, making it effective for hunting and self-defense.

.44 Magnum +P
This ammunition has a higher velocity and energy than standard .44 Magnum ammo, making it a popular choice for hunting and self-defense.

9mm +P ammo is a variant of the standard 9mm cartridge that has been loaded to a higher internal pressure.

This increased pressure results in higher velocity and energy output, which can lead to improved performance in certain firearms and shooting situations.

9mm +P Ammo vs Regular 9mm Ammo
The primary difference between 9mm +P ammo vs regular 9mm ammo is the internal pressure of the cartridge.

9mm +P ammo is loaded to a higher pressure than regular 9mm ammo, resulting in a higher muzzle velocity and more energy upon impact.

However, not all firearms are rated for +P ammunition, and using it in a firearm that is not designed for it can result in damage or even injury.

Regular 9mm ammo, on the other hand, is loaded to a standard pressure and is suitable for use in most firearms chambered for the 9mm cartridge.

*Again, it's important to consult the firearm manufacturer's recommendations and consult with a qualified firearms expert before using 9mm +P ammunition.

For the 9mm Luger cartridge, SAAMI established a maximum average chamber pressure of 35,000 psi, and ammunition companies adhere to this.

After all, they don’t want their ammunition to blow up a gun. About three decades ago manufacturers began loading the 9mm to higher pressures, and SAAMI created a category for 9mm +P ammunition, with a maximum average pressure of 38,500 psi.

This increase in pressure generally amounts to about a 5 percent increase in velocity. It’s important to note that some 9mm handguns are not rated for +P ammunition.

The increased pressure and velocity can increase bullet deformation and/or penetration, but rarely both.

This is because the larger frontal diameter a bullet develops during deformation, the less it will penetrate.

Also, some 9mm ammunition is rated as +P+, meaning it exceeds the maximum allowable pressure limit for 9mm +P ammunition that has been established SAAMI. It gets complicated because SAAMI does not have a classification for +P+ ammo.

This does not mean there are no handguns that can handle +P+ ammo, most rated for +P ammunition will, but a steady diet of it is not recommended.

When it comes to deciding if you should use +P 9mm ammunition in your handgun, the first step is to determine if your handgun is rated for it.

This is generally discoverable by looking in the owner’s manual. The next consideration is if it is worth the increased wear on your handgun.

The use of +P ammunition for practice is generally not a good idea; there’s no reason to expose your handgun to the extra stress that often.

If you use +P ammo at all, it should be as carry ammo, and for the purpose of either increasing the penetration depth or the diameter of the expanded bullet, so to increase tissue destruction.

The extra velocity generally provided with +P ammo can be a good thing with short barrel handguns.

The extremely short barrels on many modern ultra-compact 9mm pistols can reduce velocity, and this can sometimes be detrimental to terminal performance.

The increased impact velocity of the bullet with +P ammo can help with bullet upset. But the increase in pressure and velocity also increases recoil, sometimes by as much as 10 percent.

This is generally not a good thing with the itty-bitty pistols that are already hard to control, and that are so popular today.

In most cases choosing a standard pressure load that has been adapted for short barrel use is a better option.

Do your own research, and your own testing – if possible – to determine if the gain in terminal performance is worth the increase in recoil and the wear and tear on your pistol?

The effectiveness of a self-defense handgun, when used to shoot a human assailant, is mostly a product of shot placement and penetration.

An extra tenth of an inch in bullet upset and the decreased shootability of the handgun might not be a tradeoff worth making.