It’s a common question among shooters: What is +P Ammo?
Well, the answer really isn’t all that complicated: +P ammo is simply a cartridge that has been loaded with a higher amount of gun powder. The “P” means pressure, so any time you see +P (or +P+, which packs even more powder), think to yourself “pressure.”
+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.
This type of ammo allows gun owners to move up in speed and terminal ballistics without purchasing a larger gun and moving up in cartridge size. Essentially, if you have a gun that takes 9mm ammo, you can increase your velocity and power with 9mm +P cartridges without purchasing a new firearm. (Assuming your gun can handle +P ammo; more on gun specs below.)
+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.
Standard vs. +P: A Look at the Numbers
To compare standard ammunition to +P rounds, let’s take a look at two cartridges from the same manufacturer that are exactly alike in every way except for the +P designation. Critical Defense, a line of personal-protection ammo from Hornady, is a good starting point. Their .38 Special rounds come in standard and +P, and both have 110-grain FTX ballistic-tip bullets, making them an even comparison.
Muzzle Velocity:
- Hornady Critical Defense .38 Special: 1,010 feet per second
- Hornady Critical Defense .38 Special +P: 1,090 feet per second
Muzzle Energy:
- Critical Defense .38 Special: 249 foot-pounds
- Critical Defense .38 Special +P: 290 foot-pounds
As you can see, the +P ammo has slightly higher speed and power, creating enhanced terminal ballistics.
Let’s look at another example. This time, we’re examining 9mm Luger Speer Gold Dot Personal Protection 124-grain rounds in both standard and +P.
Muzzle Velocity:
- Speer Gold Dot 9mm Luger: 1,150 feet per second
- Speer Gold Dot 9mm Luger +P: 1,220 feet per second
Muzzle Energy
- Speer Gold Dot 9mm Luger: 364 foot-pounds
- Speer Gold Dot 9mm Luger +P: 410 foot-pounds
Once again, we have higher ratings for speed and energy thanks to the higher internal pressure.
Why Use It? What Are The Advantages of +P Ammo?
There are two specific advantages of using +P ammunition. Primarily, most people choose +P ammo for greater terminal ballistics. When the projectile makes contact with a target, hollow point bullets turn forward energy into penetration and expansion. The faster the bullet is moving, the deeper it will penetrate and the better it will expand. Expansion is a particular concern for anyone using self-defense rounds, making +P ammo an ideal choice for conceal-carry weapons.
Although not as much of a concern, +P ammo also provides greater straight-line trajectories. Here are the trajectory stats for the Speer Gold Dot 9mm Luger ammo we discussed above:
Speer Gold Dot 9mm Luger Ammo:
- 25 Yards: 0
- 50 Yards: -.9
- 75 Yards: -3.8
- 100 Yards: -8.9
- 25 Yards: 0
- 50 Yards: -.8
- 75 Yards: -3.3
- 100 Yards: -8.0
As you can see, the enhanced speed helps the bullet maintain a straighter trajectory for a longer distance. That increased power can mean significant differences in how the ammo performs for both a competition and a self-defense load.
To get an idea of the difference when used in a self-defense setting, we lined up our standard load and our +p Speer Gold Dot 9mm ammo. We fired each round into a calibrated, 16-inch block of Clear Ballistics gelatin. You can see the results of that test in the photograph above. From most shooter’s perspective, the +p load performed in a way that’s more desirable for self-defense – it brought a more expansive wound channel that likely would have inflicted more damage to a target than the standard-pressure load.
That difference in performance could be tied to the wider diameter we saw from the +p expanded bullet than our standard counterpart. You can see the difference in side of the fired rounds in the photo below.
Are There Disadvantages of +P Ammo?
There are a few disadvantages to using +P, and it all relates to the higher internal pressure of the rounds. By far the biggest concern is whether or not your gun is built to withstand the higher internal pressures. Not all handguns can withstand the higher internal pressures of +P ammunition, and shooting +P rounds from a gun not made to handle the pressure can case damage to the firearm which could result in significant injury.
The other disadvantage is increased recoil with +P. Because of the pressure and velocity, there is also an increase in the kick that you experience from shooting these rounds. This can make shooting high-pressure ammo more difficult, especially for smaller or weaker gun owners as you’re more likely to be taken off-target while firing several shots in a row.
Is +P Ammo Safe?
This is the most important part about using these types of cartridges: your firearm must be rated to handle +P ammo. If you are using +P ammo, it can cause significant strain on the internal components; especially if you have an auto-loading handgun. Using +P ammo in a weapon that is not rated for higher pressure will eventually ruin the gun and could cause serious injury to the user.
So how can you tell if the weapon is rated for +P ammo? If the gun is older, it’s likely not built for +P ammo, but age is not a reliable metric. If you have access to the gun’s manual, it should say whether or not it is rated for +P rounds. You can also take the firearm to a gun dealer or gunsmith who may be able to research the weapon and provide the information you need.
