Understanding P Ammo: Pressure, Performance, and Risk

What Does P Mean in Ammo?

When discussing ammo, the term 'P' is often associated with higher pressure and enhanced performance. However, it also comes with significant risks. This article delves into what P ammo means, why it is important, and how it should be used safely.

P Ammo: Higher Chamber Pressure

All firearms are not created equal, nor are all ammo. Some firearms are designed to shoot P ammo, which means they can withstand higher chamber pressures. The P designation indicates that the ammo is above the standard pressure set by many agencies, with SAAMI (Society of Automotive Engineers, Inc.) being the primary regulatory body. These pressures can be significantly higher than standard, often reaching levels comparable to military standards.

For instance, P ammo is typically designed for the most modern and sturdy pistols and submachine guns (SMGs). A Glock 17, for example, is well-suited for high-pressure rounds. However, not all firearms can handle such intense pressures. Many pistols would struggle to reach the 33,000 rounds that a Glock 17 can manage with P ammo.

SAAMI Ratings for Civilian Ammo

The SAAMI ratings for civilian ammo serve as the standard for what firearms are capable of handling. P ammo pushes these standards to the limit, providing chambers with pressures that are about 10% higher than the standard. This increased pressure translates to more energy being delivered to the projectile, increasing the ammo's performance. P ammo is approximately on par with the NATO military standard, making it the upper limit for civilian use.

While P ammo offers enhanced performance, it also poses risks. These pressures are close to the proof pressures, which are the maximum pressures firearms are designed to handle. Exceeding these pressures can have severe consequences, including potentially damaging your firearm or even posing physical risks to the shooter.

High Pressure vs. Magnum Performance

The designation 'P' in ammo indicates that it provides more pressure than standard ammo. This higher pressure results in more energy being transferred to the projectile, enhancing its performance. For the .38 Special, P ammo was developed to extend the service life of police revolvers. The .357 Magnum already delivers high chamber pressure, and 'P' ammo further approaches this performance level.

However, the higher pressures of 'P' and especially 'P' ammo can be very brutal on the frame of revolvers. Even high-quality revolvers like the Smith Wesson K Frame have been known to experience issues with loose screws after extended use. One example is a gentleman who habitually fired 'P' ammo in his Taurus .38 caliber revolver, which resulted in the barrel going downrange with the projectile one day.

Most modern pistols are designed to withstand the pressures of 'P' ammo, but it is essential to check the manufacturer's recommendations. Some firearms may not be rated for 'P' ammo and could suffer damage or failure under these conditions.

Conclusion

While P ammo offers significant performance benefits, it comes with considerable risks. It is crucial for shooters to understand the pressure ratings of their firearms and to only use ammo that is safe for their guns. By being aware of the risks and following safety guidelines, shooters can enjoy the benefits of high-pressure ammo while minimizing the potential for damage or accidents.