What Is +P Ammo? Overpressure Explained (and Is It Safe in Your Gun?)

Summary

+P means overpressure: the round is loaded about 10% above standard SAAMI pressure for more velocity and energy. SAAMI sets +P limits for a few calibers, including 9mm and .45 ACP. It is safe in modern guns rated for it, so check your manual. Expect more recoil and faster wear. +P is a modest gain in 9mm and most useful in short-barrel guns.

You will see +P stamped on defense ammo boxes. It stands for overpressure, and it means a little more power from the same cartridge.

Here is what +P actually does, whether it is safe in your gun, and when it is worth carrying.

What +P Actually Means

SAAMI sets the pressure standards for ammunition. A +P load is built about 10% above the standard pressure for that caliber. Higher pressure means higher velocity and more energy from the same bullet.

For example, standard 9mm tops out near 35,000 psi, while 9mm +P is rated to 38,500 psi. SAAMI lists +P for a few calibers, including 9mm, .45 ACP, and .38 Special. “Higher pressure” is not “high pressure”: +P is far below magnum levels.

Is +P Safe in My Gun?

Most modern handguns are rated for +P. Check your owner’s manual or the barrel markings to be sure. If it says +P is fine, it is fine.

Be careful with older guns and lightweight alloy frames not rated for it. And avoid +P+, which has no SAAMI standard and can be loaded to unknown pressure.

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A +P defense load to picture as we go:

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What You Gain (and Give Up)

The gain is real but modest: often 50 to 100 fps and more energy, which can help a hollow point expand. Atomic’s 9mm +P 124gr makes 396 ft-lbs; its .45 ACP +P 185gr makes 534 ft-lbs.

The cost is more recoil, more muzzle blast, and faster wear on the gun. That is why most shooters carry +P but practice with standard-pressure ammo.

When +P Is Worth It

The +P edge matters most in short-barrel guns, where a standard load loses speed. The extra velocity can help a hollow point open reliably.

In a full-size 9mm, modern hollow points already perform well at standard pressure, so +P is a nice-to-have. Carry what runs reliably in your gun, and train with standard ammo to save wear.

Frequently Asked Questions

What does +P mean on ammo?

It means overpressure: the round is loaded about 10% above standard SAAMI pressure for more velocity and energy. It is a defined standard, not random hot ammo.

Is +P ammo safe?

Yes, in a modern firearm rated for it. Check your owner’s manual. Avoid +P in older or lightweight guns not rated for it, and avoid +P+ unless your gun is specifically rated for it.

Does +P wear out my gun faster?

It adds stress, so heavy +P use can speed wear on springs and other parts. Most shooters carry +P and practice with standard-pressure ammo.

Is +P worth it in 9mm?

It is a modest gain. It helps most in short-barrel guns. In a full-size pistol, modern standard-pressure hollow points already perform well.

What is +P+?

A load above +P with no SAAMI standard, so the pressure is set by the maker. Only use it in a gun specifically rated for it.

Choose a defense load that fits your gun. Compare the lineup below. Related reading: what is a hollow point bullet and what grain means.

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