What is +p?

[Dr.Rob]

Based on this weekends' Colorado THR shootout, and some informal use of Billl's chrono...

My poor lil old Luger, shooting Winchester Whitebox 115 gr 9mm ammo was clocking 1175-1200fps with regularity...the FEG Hi-Power clone was averaging OVER 1200 fps every shot with the same ammo

Now while I figured hmmm... high altitude.. better check another load... the Winchester 45 ACP FMJ (rated at 835) was getting 840-845 from my 1917 revolver and similarly consistant results from my 1919 Government Model.

Many 9mm ammo producers rate +p at over 1150... (Firearms tactical relates Remington 115gr +p+ at 1221fps)

My .357 load.. 6.5 gr of red dot/158gr sjhp bullet was clocking a woeful 910fps out of my Colt snubby... hardly the hammer of thor though it hits with authority.

So how fast is your +p ammo?

 

[Moonclip]

Interesting, my fav 9mm defense load, Rem 115gr jhp plus p clocks like at 1250 I believe but I think Winchester non plus p 115gr JHP value pack hollowpoints clock at 1225. Much foreign ammo is not rated plus p but runs on the warm side also.

 

[Zundfolge]

More and more I'm convinced that +P is 100% marketing.


Corbon 135gr .40 S&W is labeled as +P when there is no such thing as +P .40.



Of course I was getting 3500fps out of the 147gr JHPs I was shooting out of my Kahr MK9

 

[thatguy]

+P? Sounds like algebra to me.

 

[Dr.Rob]

Or rather your unburned powder was... then again I would NOT have been suprised at that reading from Brass' .357 Sig.

It wasn't unpleasent to shoot (though the grip didn't 'fit me') it sounded like a monster.

 

[Zak Smith]

Some handgun calibers (not all) have a SAAMI-defined "+P" maximuim average pressure ("MAP") rating whch is typically 10% over the standard MAP for the caliber.

For example, 9x19mm MAP is 35,000 psi. 9x19 +P MAP is 38,500 psi.

It has nothing to do with velocity except that velocity-optimized +P loads will be faster than velocity-optimized normal pressure loads for the same bullet mass. It is certainly possible to have a slower load with higher pressure, e.g. if a faster-burning powder is used.

-z

 

[Dr.Rob]

That's my point... no matter what the pressure in the chamber the end result is throwing a known mass at X velocity...

Too much pressure can blow up your gun before you even get the desired effect of higher velocity right?

You can have a +p load (high PRESSURE) that really has NO better value, other than increasing the stress on the barrel/chamber for the same desired result.

 

[Zak Smith]

Sure, it can blow up before you get the velocity you want. You'll never get a 124 @ 1200 with Bullseye, but it's easy with the right powder (e.g. 3N37 and others). In other words, if you are shooting a "+P" labelled load for more velocity and aren't getting it, then that is probably a poorly-designed load.

The IPSC crowd often uses heavy bullets and fast powders in order to affect the recoil impulse and slide velocity. This results in higher pressures than using the same bullets and moderate or slow powders. But we're typically using strong guns and loading "long" to reduce initial pressure.

 

[Dr.Rob]

Ok I hadn't thought of 'slide velocity' in the mix... still the question I'm asking is in our fellow members 'carry ammo' (whatever that means) what kind of speed are you really getting?

 

[Zak Smith]

Speer Gold Dot 124gr +P shoots 1300fps in full size 9's for me.
It's possible to shoot 147's at 1100fps with the right powder.

 

[sumpnz]

I have the data at home, but IIRC WWB 230gr hardball (.45ACP) was clocking ~780fps from my Sig P245 (3.9"). WWB 165gr hardball (.40S&W) was clocking at or just under 1000fps from my Ruger P94 (4.19"). I also chrono'd some Cor-bon 165gr JHP's from the Ruger. I think they were around 11-1200fps, but the consistancy was not very good. I even had one shot that was very noticably lighter than the rest. The chrono readings showed that shot was a good 1-200fps slower than the rest.

I'm planning to buy several different JHP type bullets for both the Sig and the Ruger and will be testing them the next time I'm at the range. I'll try to remember to post the results (reliability, accuracy, and velocity).