Last reviewed: 2026-04-17 by Jake Terry, FFL07/SOT3, NRA-certified firearms instructor.
Overpressure 40 cal ammo separates casual plinking from serious terminal work. Buffalo Bore’s 40 S&W +P load chambers a 180-grain full metal jacket bullet at 1100 fps muzzle velocity and 484 ft-lbs of energy — performance that demands both a fully supported chamber and a platform designed to handle sustained +P use. This is not a universal load: factory Glock 40 S&W barrels feature an unsupported chamber design that creates case-head bulging or rupture risk under overpressure. Shooters running Glocks must install an aftermarket barrel with full chamber support before firing this ammunition. All other modern 40 S&W platforms with fully supported chambers — including most 1911-style pistols, the SIG P229, Springfield XD, and Smith & Wesson M&P — handle this load within safe operating margins.
Built for the Box
Buffalo Bore loads this round with flash-suppressed powder that delivers full velocity at lower chamber pressure than conventional ball powders. That powder selection serves a tactical function: over 90% of defensive shooting incidents occur in low-light conditions where muzzle flash can temporarily blind the shooter after the first shot. The 180-grain FMJ bullet seats in new-production brass with boxer primers, non-corrosive formulation, and full reloadability. Each case headstamp may read “40 S&W” without a “+P” designation due to brass supply constraints — Buffalo Bore has confirmed all boxes contain overpressure loads regardless of headstamp marking.
The Numbers
| Spec | Value |
|---|---|
| Caliber | 40 S&W +P |
| Bullet weight | 180 grain |
| Bullet type | Full Metal Jacket Flat Base |
| Muzzle velocity | 1100 fps |
| Muzzle energy | 484 ft-lbs |
| Rounds/box | 20 |
| Case | Brass |
| Primer | Boxer |
| Corrosive | No |
| Intended use | Training, duty carry in supported-chamber platforms |
| Manufacturer | Buffalo Bore |
The flat-base FMJ profile feeds reliably through most 40 S&W magazines and reduces barrel fouling compared to hollow-base designs. Recoil impulse runs noticeably sharper than standard-pressure 180-grain loads — shooters transitioning from factory 40 S&W to this +P load should expect increased felt recoil and faster slide cycling.
Safe Handling & Compliance
Federal law requires purchasers to be at least 18 years old for rifle and shotgun ammunition, and at least 21 for handgun ammunition. Ammunition cannot be shipped to certain states, counties, and cities — review our ammunition shipping restrictions before ordering. Store ammunition in a cool, dry location away from heat sources and out of reach of unauthorized users.
- Treat every firearm as if it is loaded; keep your finger off the trigger until ready to fire; never point the muzzle at anything you are not willing to destroy; know your target and what lies beyond it. Review the NRA’s firearms safety rules.
- Verify your firearm is rated for +P ammunition and features a fully supported chamber before loading this round. Factory Glock 40 S&W barrels are NOT compatible with this load.
- Store ammunition below 120°F and away from open flame or heat sources. This product ships via DOT-regulated ground service only.
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