What +P means
+P stands for "overpressure." It means the cartridge is loaded to a higher chamber pressure than standard ammunition — typically 10–15% above SAAMI spec. The result is higher muzzle velocity from the same bullet weight, which usually translates to better terminal performance.
SAAMI (Sporting Arms and Ammunition Manufacturers' Institute) sets the pressure standards for commercial ammunition. When a cartridge is marked "+P," it means the manufacturer loaded it above standard pressure but within the SAAMI +P ceiling. It's not wildcat or handloaded ammo — it's a defined specification.
+P pressure specs
| Caliber | Standard max pressure | +P max 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 +P spec exists |
Important: Not every caliber has a SAAMI +P specification. .380 ACP and .40 S&W do not have official +P ratings. If you see .380 +P or .40 S&W +P, the manufacturer is using their own standard, not an industry spec. Proceed with caution.
What about +P+?
+P+ has no SAAMI standard. It means the load exceeds +P pressure, but by how much is entirely up to the manufacturer. +P+ ammo is primarily sold to law enforcement and should only be used in firearms the manufacturer explicitly rates for +P+ use. When in doubt, don't shoot +P+ in your gun.
Is my gun rated for +P?
Check your owner's manual. Most modern handguns from major manufacturers are +P rated:
Generally +P safe:
- Glock (all models) — Glock rates all pistols for +P
- Sig Sauer (all modern models)
- Smith & Wesson M&P series
- Springfield XD/Hellcat series
- CZ P-series
- Beretta 92/M9 series
- Most modern revolvers in .38 Special/.357 Magnum
Generally NOT +P safe:
- Older (pre-1970s) .38 Special revolvers — especially lightweight alloy frames
- Some micro .380 pistols (check manufacturer specs)
- Any firearm where the manual says "use standard pressure ammunition only"
- Vintage or surplus military pistols
If your owner's manual doesn't mention +P, contact the manufacturer before using it. Running +P in a gun not rated for it accelerates wear and can be unsafe.
Performance difference
The velocity gain from +P is real but modest:
| Load | Standard velocity | +P velocity | Difference |
|---|---|---|---|
| 9mm 124gr JHP | ~1,150 fps | ~1,200–1,250 fps | +50–100 fps |
| .38 Special 125gr JHP | ~850 fps | ~950–1,000 fps | +100–150 fps |
| .45 ACP 230gr JHP | ~830 fps | ~900–950 fps | +70–120 fps |
In 9mm, this translates to slightly more reliable JHP expansion and a bit more energy on target. In .38 Special, the difference is more significant — +P loads bring .38 Special closer to adequate defensive performance from short-barreled revolvers.
The tradeoffs
More recoil. Higher velocity means more felt recoil. In a full-size pistol, the difference is minor. In a lightweight subcompact or snub-nose revolver, +P recoil is noticeably snappier and can slow follow-up shots.
More muzzle flash. +P loads produce more flash, especially from short barrels. In a low-light defensive scenario, this can affect your vision after the first shot.
Faster wear. +P ammo puts more stress on the slide, barrel, frame, and recoil spring. In a quality modern pistol, occasional +P use causes negligible additional wear. Shooting exclusively +P for thousands of rounds will accelerate recoil spring replacement. Most manufacturers recommend replacing recoil springs at shorter intervals if you shoot +P regularly.
Higher cost. +P defensive ammo typically costs $0.05–0.15 more per round than standard-pressure equivalents.
When +P makes sense
Carry in .38 Special. +P earns its keep here. Standard-pressure .38 Special from a 2" snub-nose produces marginal velocities for JHP expansion. +P loads like Speer Gold Dot Short Barrel 135gr +P bring .38 up to acceptable defensive performance. If you carry a J-frame revolver, +P is practically mandatory.
9mm from micro-compacts. Some defensive 9mm loads benefit from the extra velocity to ensure expansion from barrels under 3.5". Federal HST 124gr +P is popular for this reason.
When +P doesn't make sense
Standard 9mm carry. Modern 9mm JHP designs (Federal HST, Speer Gold Dot) expand reliably at standard pressures from 3.5"+ barrels. The marginal velocity gain from +P doesn't change the outcome enough to justify the added recoil, especially in a gun you need to shoot quickly and accurately under stress.
Range training. Never train with +P. It costs more, beats up your gun, and adds nothing to practice. Train with standard-pressure FMJ that approximates your carry load's weight.
Guns you're not sure about. If you can't confirm +P compatibility, don't risk it.
The bottom line
+P ammo is safe in guns rated for it and offers a meaningful velocity boost in marginal calibers like .38 Special. For 9mm, it's a nice-to-have, not a need-to-have — standard-pressure modern JHP already performs well. Check your manual, use +P for carry if it improves your chosen load's performance, and always train with standard-pressure ammo.
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Related articles
Sources
- SAAMI +P Pressure Standards — Official overpressure specifications
- 9×19mm Parabellum — Wikipedia — +P and +P+ history
- Speer Gold Dot Products — +P ammunition specifications