What does +P mean on ammunition?
+P ("plus P") marks a cartridge loaded to a higher maximum average pressure than the standard load for that caliber, within a separate +P limit set by SAAMI (the Sporting Arms and Ammunition Manufacturers' Institute). The higher pressure produces more muzzle velocity from the same bullet weight. In 9mm Luger, for example, SAAMI's standard limit is 35,000 psi and its +P limit is 38,500 psi, and Federal publishes 1,150 fps for its standard 124gr HST against 1,200 fps for the 124gr HST +P.
+P is a defined industry specification, not a handload or a "hot" one-off: a SAAMI-member manufacturer loading a +P cartridge is working to a published ceiling. It exists only for some calibers, and it is safe only in firearms rated for it.
What are the +P pressure limits by caliber?
| Caliber | Standard max average pressure | +P max average pressure | Increase |
|---|---|---|---|
| 9mm Luger | 35,000 psi | 38,500 psi | +10% |
| .38 Special | 17,000 psi | 20,000 psi | +18% |
| .45 ACP | 21,000 psi | 23,000 psi | +10% |
| .380 ACP | 21,500 psi | — | No SAAMI +P specification |
| .40 S&W | 35,000 psi | — | No SAAMI +P specification |
Figures are SAAMI maximum average pressures measured by the piezoelectric transducer method. Where a caliber has no SAAMI +P specification, a box marked "+P" in that caliber reflects the manufacturer's own standard rather than an industry one, and the manufacturer is the only source for what it means.
What is +P+ ammo?
+P+ has no SAAMI specification at all. It indicates a load above the +P limit, by an amount only the manufacturer knows. +P+ ammunition has historically been sold mainly to law-enforcement agencies for firearms their makers approve for it. Firearm manufacturers that address +P+ in their manuals often restrict or disallow it, so the manual is the deciding document.
Is my gun rated for +P?
The owner's manual or the firearm manufacturer answers this; there is no general rule by brand. Many current-production service pistols in 9mm and .45 ACP are rated for +P, and many manufacturers also note that a steady diet of +P increases wear and shortens spring-replacement intervals.
Cases that call for checking before firing +P:
- Older .38 Special revolvers, especially lightweight alloy-framed models and guns made before +P loads were common
- Small, lightweight pistols, where the manufacturer may limit +P use
- Any firearm whose manual says to use standard-pressure ammunition only
- Vintage, surplus, or modified firearms
If the manual does not address +P, the manufacturer's customer service can confirm it by model and serial number. Firing +P in a gun not rated for it adds stress the design was not built to handle.
How much faster is +P?
Published velocity for a matched pair of loads from one manufacturer shows the size of the change cleanly, because the bullet and test barrel are the same:
| Load (4" test barrel) | Standard | +P | Difference |
|---|---|---|---|
| Federal Tactical HST 9mm 124gr (P9HST1 vs P9HST3) | 1,150 fps / 364 ft-lbs | 1,200 fps / 396 ft-lbs | +50 fps / +32 ft-lbs |
Speer publishes 1,220 fps and 410 ft-lbs for its 124gr Gold Dot +P (53617). In .38 Special, the relative pressure increase is larger (about 18%), and +P is common in defensive loads for short-barreled revolvers, where standard-pressure velocity is lowest. For the full 9mm velocity tables, see the 9mm ballistics chart.
What are the trade-offs of +P?
More recoil. More velocity from the same bullet weight means more recoil momentum. The difference is most noticeable in light pistols and small revolvers.
More muzzle flash and blast. Especially from short barrels, which can affect vision in low light.
More wear. Higher pressure puts more stress on the slide, frame, barrel and recoil spring. Manufacturers that rate a gun for +P may still shorten recommended spring-replacement intervals for frequent +P use.
Cost. +P loads are mostly premium defensive ammunition, so they are priced alongside other defensive hollow points rather than practice FMJ. Current tracked prices: 9mm +P and .38 Special +P.
Where is +P commonly used?
.38 Special defensive loads. Standard-pressure .38 Special from a 2-inch revolver produces low velocities for hollow-point expansion, and many defensive .38 Special loads, including short-barrel designs, are +P.
9mm defensive loads. Several duty-class 9mm lines (Federal HST, Speer Gold Dot, Hornady Critical Duty) are offered in +P alongside standard pressure. Some shooters use +P to offset velocity lost in short barrels; others use standard pressure for lower recoil. Manufacturers publish test results for each, and the 115 vs 124 vs 147 grain guide covers how weight interacts with velocity.
Practice. +P is uncommon for practice: it costs more, adds wear, and practice FMJ in standard pressure is the norm. A common approach is to practice with standard-pressure FMJ of the same bullet weight and fire enough of the +P carry load to confirm it functions in the specific gun.
How do you tell if ammo is +P?
The headstamp on the case base usually reads "+P" (for example, "9mm Luger +P"), and the box label states it. If a loose round has no +P headstamp, treat it as unknown rather than standard. When ammunition is mixed or unmarked, the original packaging or the manufacturer is the reliable source.
Compare .38 Special +P hollow point prices → | Compare 9mm +P hollow point prices →
Related articles
- 9mm ballistics chart
- FMJ vs hollow point
- 9mm concealed carry loads compared
- 115gr vs 124gr vs 147gr 9mm
Sources
- SAAMI Cartridge & Chamber Drawings — Maximum average pressure specifications
- Federal Tactical HST 9mm Luger +P (P9HST3) — +P velocity and energy
- Federal Tactical HST 9mm Luger (P9HST1) — Standard-pressure velocity and energy
- Speer LE Gold Dot 9mm Luger +P (53617) — +P velocity and energy