is +P Ammo Bad for my Gun?

I shoot a lot of low-pressure ammo but also do like +P. Especially for defensive handgun ammo.

Modern guns can handle +P ammo. Most +P cartridges are not listed by SAAMI but are crafted well below the SAAMI safe operating limits. There are only 4 +P cartridges approved by SAAMI: 9mm+P, 38 Special+P, 45 Automatic+P, and 257 Roberts+P. Other +P cartridges are available and are considered safe in any modern gun.

What is +P ammo and why does it exist? is it completely safe, and what’s the advantage? Well, let’s take a closer look at what +P ammo is.

What is +P Ammo?

+P ammo is extra-pressure ammo loaded to approximately 10% more expected pressure than the non + P standard. Several cartridges have been completely replaced by +P versions by SAAMI, the governing body in firearm and ammo manufacturing. Many +p offerings are actually loaded well under the allowed pressure.

Not all +P is actually +P. Some companies always underload their ammo and end up creating a +P load that barely reaches non +P standards. I see a lot of the so-called extra pressure ammo that has a published velocity within the normal range. What gives? They advertise extra power ammo then don’t really give it?

There are some manufacturers that consistently load their ammo on the lower velocity side. They sometimes offer a load that’s more powerful than their regular offering and call it a +P, but it’s still only standard pressure and gives standard results.

In fact, all +P ammo from major manufacturers is loaded well below the max allowable pressure. In my experience, their standard pressure ammo is also loaded well below operating pressure standard.

They do this for legal reasons. Although the max is still well within safe operating limits, their lawyers told them to load less pressure.

Can +P Ammo Break my Gun?

+P ammo is considered safe for any modern firearm in good condition, but gun companies often issue warnings about using it for calibers other than 38 Special, 9mm, 45acp, and 257 Roberts. +P in other calibers is not specified by SAMMI and is considered a “wildcat cartridge”. Gun manufacturers tell you not to use a non-SAMMI-approved load.

Being extra power, it will wear your gun a bit more. Not a lot, but a bit more. like driving your car fast, it won’t break it, but it’s going to put wear on the engine faster. +P ammo is not recommended for regular shooting. It’s too expensive for that anyways.

`You can fire it to see how much it recoils, and to get some practice shooting that particular load, but it’s best to just use cheap target ammo for the bulk of your practice time. It’s just more practical. Using +P ammo a few times will not harm your gun.

My wife and I both carry +P in our pistols and we shoot it now and then. It’s not too hard on either my Glock 20 or her Remington R51. It’s not going to break either of our guns used like that.

What’s the Advantage of +P Ammo?

The advantage to +P ammo is more power. It’s especially nice for the smaller defensive handgun calibers. +P ammo gives you a step up in power, allowing you to put more energy into a target. +P ammo creates larger wounds and tends to have less drop.

For both defense and hunting, it has its place. It takes your gun and gives it a step up in what it can do. Not a huge step, just around 10% or so.

I shoot Buffalo Bore +P in my 10 Glock. It’s not approved by SAMMI, but it’s safe and tested. That’s my woods carry ammo for hunting or protection in the wilderness. I don’t practice with it much, but I do carry it.

What is +P+ Ammo?

+P+ ammo is any ammo designed to create more pressure than a +P cartridge or more than 10% over a non +P cartridge. +P+ is not a SAAMI designation and is left up to the discretion of ammo manufacturers to regulate. +P+ ammo is offered predominately by specialty ammo manufacturers who deal in high-pressure and custom loads.

+P+ ammo is safe to use in accordance with manufacturer guidelines. Mainly, do not use it in a lightweight alloy-framed revolver as it may cause changes in bullet seating depth. Most companies do not make +P+ ammo. the ones that do often list specific firearms that are safe to use it in.

The most notable maker of overpressure ammo is Buffalo Bore. I love their stuff. They have tested a wide assortment of handguns and rifles and come up with a list that will handle their +P+ loads. They only offer s few options in +P+ because not all guns can handle it. Theirs is likely the most powerful on the market.

So, since we’re playing with pressures, just how much pressure can a gun take? that depends on the specific gun, how much it weighs, and how it’s made. Every gun sold in the US has to be proofed at pressures well above even the hottest +P ammo. Handguns are proofed at around 45 % higher pressure than the operating standard.

Proofed means that after firing 3 proof loads, there were no measurable changes to any part of the gun from the extra pressure. So, nothing stretched or warped out of shape.

Here is a chart of the SAAMI-approved +P loads, their operating pressures, and their proof pressures.

How much pressure can a gun take? Catastrophic (dangerous) failure of a gun can happen as low as 75,000 psi. Some guns can handle quite a bit more than that, but when we see anything reaching the 70,00 psi mark, we get scared. That’s a lot of pressure.

I know some handloaders (shooters loading their own ammo) will push certain cartridges in certain guns to that, and even past it at times. Definitely a dumb idea. The results are interesting, but it’s pretty stupid to try.

The more likely issue with pushing the limits is damaging the bolt, and cracking the slide of a semi-automatic. While +P is fine for any new semi-auto firearm, +P+ is not. It generates too much energy for proper function. +P+ is really only for use in certain revolvers, single-shots, bolt-actions, and leverguns. The manufacturer will specify.