What About +P Ammunition?

A Heckler & Koch VP9 with Federal 9mm 124gr +P ammo.

The Great Guns ‘N Ammo surge of 2021 shows a slight sign of cooling. While prices have not changed much, inventory is present. You may be tempted to bolster your reserves, especially since the government seems to delight in running it’s mouth and issuing death threats to the citzenry.

The common calibers of rifle and pistol ammo can be picked up with ease either online or at your favorite local gun shop. Prices are still somewhat high, but it is what it is. But inventory is there, and discerning Second Amendment Radicals may even see in-stock rare variants of your favorite defensive pistol caliber, such as 9mm +P and .45 ACP +P.

“+P?”, you may ask, “What is +P”?

It’s actually not terribly complicated - +P ammunition is simply ammunition that has been loaded to a higher pressure than the standard specifies. Yes, most ammunition out there is manufactured and loaded to a published standard, as defined by two major bodies, the Sporting Arms and Ammunition Manufacturers’ Institute aka SAAMI and the Commission internationale permanente pour l’épreuve des armes à feu portatives aka the CIP.

For reference, SAAMI handles standardization for the US market, and the CIP generally deals with the European market. Both bodies generally communicate and agree with each other on most standardization topics though - if SAAMI standardizes an ammunition type, CIP usually follows soon after, or vice versa.

Anyway, each body defines the physical dimensions of an ammunition cartridge, along with the pressure generated by the round when it is ignited, among other things. If you really want to nerd out, you can go to the SAAMI and CIP website, even.


Standard versus +P Ammunition

With the pressure being a set standard, a +P rating is often defined as an add-on to the standard, to provide a benchmark for ammunition designated as such.

Making a given cartridge +P is rather simple, and usually accomplished by loading it up with more gunpowder, or a powder with a different burn rate.

The idea, of course, is to increase projectile velocity over the standard, allowing users of a given pistol to utilize more powerful ammunition, without having to purchase a new firearm, or upgrade their existing one with a new barrel, for example.

More velocity, of course, means better terminal ballistics. Which means a successful hit on a threat is more likely to produce an incapacitating wound, and thereby stopping the fight sooner.

That being said, a +P rating is determined by the pressure, and not the velocity. For example in the case of 9mm:

  • 9mm Luger/Parabellum chamber pressure: 35,000 psi/241 MPa
  • 9mm +P chamber pressure: 38,500 psi/265 MPa

So, 9mm +P is a 10% increase over 9mm Parabellum, with a (hopefully) attendant velocity increase.

Another example would be for one of my favorites, .45 ACP:

  • .45 ACP chamber pressure: 21,000 psi/145 MPa
  • .45 ACP +P chamber pressure: 23,000 psi/159 MPa

Which is roughly 9.5% of an increase.

Why Use +P Ammunition?

As stated above, +P ammunition exhibits greater terminal ballistic performance as compared to a similar cartridge loaded to standard pressure levels. Let’s be blunt, a pistol isn’t an ideal self-defense weapon, but it’s not always feasible to tote around a rifle or shotgun for defensive use on a daily basis. Hence, the science of pistols and especially pistol ammunition has focused on producing better terminal ballistics in a smaller package.

From the get-go, unless you have a monster pistol at your side, you’re dealing with maybe a 4-inch barrel at best, which doesn’t give your ammunition, of any caliber, much space to work with to get up to an effective velocity. Velocity is crucial in a defensive pistol round, The faster the bullet is moving, the deeper it will penetrate and the better it will expand.

This is especially advantageous with those who choose to carry compact or subcompact pistols, where every foot-per-second counts. Even in duty-sized pistols such as the GLOCK 17 or the Heckler & Koch VP9, +P ammunition can be considered an “insurance” factor. Interestingly enough, several law enforcement agencies around the nation specify a +P cartridge for their officers, typically something along the lines of Speer‘s famous 9mm 124gr Gold Dot Hollow Point +P, which has years of proven performance on the street.

Also, with the faster velocity, +P ammunition provides greater straight-line trajectories, leading to increased accuracy. As long as you’ve trained to handle the increased recoil, of course.

Why You May Want To Avoid +P Ammunition

There’s a few small disadvantages to using +P ammunition, and it all ties into the increased pressure of the rounds.

The biggest showstopper is whether your firearm is designed to handle the higher pressures of +P ammunition. While 1 round of +P in a batch of 100 loaded to standard pressures is unlikely to cause a catastrophic failure, you should check your firearm’s specifications to ensure it can handle +P.

In not so many words though, any firearm from a major manufacturer made in the past few decades will handle +P ammunition nicely. Check the specs though, to be safe.

Another concern is wear and tear on your firearm if you use +P ammunition a lot. Higher pressures subject the gun to more stress, and components will wer out quicker. Though to be fair, if you run enough +P ammo to wear out a barrel, recoil spring, and things like the extractor, you can afford to replace those components. A good recoil spring will last thousands of rounds, and if you run that many rounds in +P, you can afford a $30 spring, ha ha.

And yes - recoil can prove off-putting, though unless one is coping with a disability or an injury, the added recoil of +P can easily be trained around, especially if one is using 9mm - +P full-metal jacket 9mm does exist, and barring that, 9mm loaded to NATO spec is relatively close to +P pressures as well.

A Heckler & Koch VP9 with a variety of +P+ ammo.

A Word on +P+ Ammunition

Beyond +P, there exists ammunition loaded to sometimes insanely-high pressures, usually covered by the +P+ designation. +P+ is not a SAAMI or CIP designation. For lack of a better term, it’s kind of a marketing concept to designate ammo loaded to pressures well in excess of standard. For example, there exists a 115gr 9mm Gold Dot Hollow Point cartridge produced by Speer, SKU 53612 that is loaded to 40,000 PSI, which is over 20% more than the 9mm Parabellum specification. You’ll also see a 9mm +P+ load called 9BPLE that was produced by Federal pop up on occasion.

Typically if produced in quantity, these loads are produced at the request of government agencies for specific use cases, for example the Federal 9BPLE load was produced for the Border Patrol, and served them well for decades. If seen in citizen hands, it’s typically a surplus or contract overrun sale.

Also, like +P - +P+ ammo does wear on your gun some more, so make sure it is up to the task.

That being said, +P+ ammo in any caliber doesn’t present an insane advantage over +P. If you run across some, grab it, of course, but realistically it’s a novelty and a conversation piece. If +P doesn’t neutralize a target, +P+ isn’t likely to fare much better.

Standard Pressure Has It’s Place

Sure, velocity is the primary factor in terminal ballistics. +P loads are often sought out by discerning Second Amendment Radicals and armed citizens, as well as professional users for their excellent performance characteristics, with only mild downsides. However, they are always building a better bullet. The science of projectile design has led to advances where a standard-pressure round can be the equal or even outperform a +P load. Do your research, and purchase accordingly.

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