What does "+P" and "+P+" mean?

[tipoc]

carguychris,

That's about what I recall as well.

I'm not sure when the 147 gr. loads became a standard in the subguns. I seem to recall it was either during or shortly after WWII. I may be wrong though.

Seems I recall as well that in the wake of the Miami shootout the FBI initially recommended switching from 115 gr. 9mm loads to the 147 gr. loads hoping for deeper penetration. Many local police Depts., which had just gone to the 9mm from revolvers, followed the FBIs lead and soon had problems with their weapons reliably functioning.

IIRC the problems were caused by a number of factors in a variety of guns. The oal of the cartridges, the weight of the recoil springs which had been carefully calibrated for 115 gr. bullets, unfamiliar recoil, etc. These early problems gave the 147 gr. loads a bad rep for quite some time.

Meanwhile a number of US agencies, the Border Patrol being one. wanted a more powerful loading of the 9mm in a jhp. A +P load. Eventually they got it

tipoc

[Hal]

There is no direct correlation between pressure and velocity. Numerous other variables come into play.

My guess is that the precise 10% velocity increase is a coincidence.
__________________

Yep - sometimes +P can even be slower than standard pressure.
The old 125 gr NyClad was like that.

Here's a post from a member back in 2000:

LIProgun
Senior Member


Join Date: August 27, 2000
Location: Hudson Valley, NY
Posts: 490 Here is some actual chronograph data, from my testing.

Using a 2" Colt, the standard pressure .38 Special 125 grain Nyclad gave a 10-shot average velocity of 843 fps, for 197 ft-lbs energy. Extreme spread was 84 fps, and Sd was 26.7.

From the same gun, the +P version gave a 10-shot average of 875 fps, for 212 ft-lbs energy. Extreme spread was 60 fps, and Sd was 17.5.

Both tests were run on the same day, with a temperature of 60 degrees.

Regarding the factory specs, remember that the standard pressure listing is from a 2" barrel, and the +P load is from a 4" barrel. The standard pressure load is actually designed to perform from a 2" barrel (and was once even called the "Chief's Special" load), and really performs as advertised.
__________________
MOLON LABE.

Pretty ugly eh?

[Cheapshooter]

what does "+p" and "+p+" mean?


Usually it just means that you feel the gun you have is inadiquate and you wish you had a more powerful cartridge.

Bingo!!! We have a winner!!!

[Silent Bob]

I guess .45 ACP is considered inadequate then.

[Cheapshooter]

I guess .45 ACP is considered inadequate then.

By people who carry a 10MM!!! And on, and on, and on.