What % gain from +p to +p+

I recently tested the two versions of speers 124 grain 9mm gold dot from my 2" 905 revolver.

The non +p version came in right at 1180 fps and the standard pressure loading average pretty much 100 fps on the dot slower.

I did Chronograph one round of the infamous L7a1 +p++ subhuman ammo, it went over my skyscreens at close to 1250 fps

In my opinion if +p is avalible and functions there's no downside to its use.

Nobody really knows what constitutes a +P+ -- for all we know it could be marketing hyperbole -- so the only way to know would be to chronograph a sampling.

I did Chronograph one round of the infamous L7a1 +p++ subhuman ammo, it went over my skyscreens at close to 1250 fps

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+P++?

standard SAMMI pressure defines a particular upper limit
above that pressure AND below another pressure is known as +P
Above the higher pressure is +P+ ... with no defined upper limit

Super-awesome pressure gauge graphic follows:
__
|| - maximum possible pressure (given case volume and available propellants/primer/etc)
|| ~ somewhere around here is "surprise hand grenade"
||
|| ~ somewhere in here is submachinegun ammo, designed for a gun very different than a standard pistol in whatever caliber we're discussing
||
|| - +P+ territory extends upwards forever with no defined upper limit
|| - here and above is +P+
|| - Maximum acceptable +P pressure
|| \+P pressure band
|| /(safe for most sturdy modern designs)
|| - beginning of +P territory
|| - SAMMI limit for non +P ammo (in the case of 9x19, the "9mm NATO" load is around here)|
|| \
|| -\"normal pressure" region,
|| -/ most factory loads
|| /
|| - minimum operating pressure for your given load
||
||
|| - Zero pressure

Depends on what you are trying to do I guess. It has real pop!


I Chrony'd Underwood's GD last week 115gr +P+. It was 1520 FPS/ 600 LBS out of my 4" XD barrel. That's mid 10mm level


It would be devastating and excellent for woods. Probably overkill for HD but if you had a short barrel gun you still pack the ooomph!

I assumed you meant 9mm:

https://docs.google.com/spreadsheet/ccc?key=0Ak5OC6bPsjO8dC04eEk2U2xaYXJLVGppTHMtQWJISHc#gid=0

I carry +P. I suspect that you get less out of +P+ over +P than most people think. I think if you want +P+ why not just go to .357 Sig?

I've always held if you want high performance; buy high performance. Holds true for cars, boats, motorcycles, cameras, guns and etc.

If I want +P+ in a .355" bullet, I'll swap out my 40 for my 357 Sig barrel and load what I want.

My PACT2 chrono reports 1,400 - 1,425 with a Honady 124 grain XTP bullet over 11.0 grains Blue Dot powder.

That's good enough for me.

Does the higher preassure make it not worth using in most guns, even if they take it?

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I think the extra velocity is worth a little extra recoil. As long as your using a decent sized gun you'll hardly notice it.

What percentage is gained with velocity? Well lets see, for example:

124 grains at 1,150 fps (standard pressure)

vs

124 grains at 1200 fps (+P load) (4.35% increase in velocity over standard pressure)

vs

124 grains at 1250 fps (+P+ load) (8.7% increase in velocity from standard pressure)

Whether you think it's worth it is up to you. I for one prefer to stick with 124 grain +P ammo.

I've shot some Federal 9PBLE +p+ 115 grain loads in my SR9-C. They weren't bad at all. I don't think Federal would manufacture ammo that would destroy handguns, so I'm not worried about using it. Plus Ruger = built like a tank.

Hi guys,

I get the speed difference. But is there a way to extrapolate what the numbers would be for different barrel lengths?

For example, if I look up the specs for Speer GD 9mm 124gr, I get some number assuming a 4" barrel. But what if I wanted to know numbers for a 3" or 5" barrel?

Also, there is a measured speed difference. But is there a practical difference? What does it mean when shot by a bullet at these varied velocities?

Generally there's about 50 fps or more difference for every inch of barrel length between 3,4 and 5 inch barrels. This is not exact though, because there are so many factors that effect the actually velocity.

But is there a practical difference? What does it mean when shot by a bullet at these varied velocities?

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Usually more velocity means more bullet expansion and possibly more penetration as well, depending on the bullet design. Some bullets will open up more and penetrate less, and some will open up more and still penetrated more. Terminal ballistics is a science with few absolute answers. As long as you use a bullet at the intended velocity, or velocity range, you are likely to have great performance.

Check this out: http://ballisticsbytheinch.com/index.html

Some people worry themselves sick about kinetic energy calculations. That's silly, expansion and penetration are what really matter. Especially with handgun ammunition.

Ben86 said:

Generally there's about 50 fps or more difference for every inch of barrel length between 3,4 and 5 inch barrels.

...
As long as you use a bullet at the intended velocity, or velocity range, you are likely to have great performance.

Check this out: http://ballisticsbytheinch.com/index.html

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Thanks for the rule of thumb. And also the link - lots of info to study later.

I'm pragmatic. How do you find the effective operating velocity range for a given bullet? I'll go back and check the specs for Speer GDHP but I don't remember any suggestive of velocity range. I agree that's the key.

Be careful when talking about penetration. It is not solely a velocity thing. While a 115 gr +P+ might penetrate more than a standard pressure 115 gr, when you go to a higher weight projectile momentum and inertia increase and such high velocities are not needed to achieve the same penetration.

How do you find the effective operating velocity range for a given bullet?

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You don't have to worry about finding it, the manufacturers do the work. Generally speaking though, most modern premium hollow points are made to work in 3" or longer barrels. They figure people will use them in their small CC guns, so they design them to operate well within a wide range of velocity. In other words they may be at their peak of performance in a 5" barrel, but will still work well in a 3" barrel. Don't worry about it.

I remember reading somewhere that the optimum velocity for the 124 grain gold dot was 1150 fps. I still prefer mine to go 1200 fps. It doesn't make a big difference though.

Ben86 said:

Generally speaking though, most modern premium hollow points are made to work in 3" or longer barrels.

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Good to know; works for me. So, I'll assume that my current stock of Speer GDHP 124gr will work okay (sufficient velocity and expansion) out of my 3.25" barrel out to reasonable distances (<15 yards). If I'm not making a good assumption, please let me know.

The next case I buy, I'll consider the Speer GDHP Short Barrel version (or the +P version -- not sure what the difference is yet) or some equivalent round. While my current round is assumed to be okay, perhaps it doesn't hurt to have a little (10%) extra headroom.

Good to know; works for me. So, I'll assume that my current stock of Speer GDHP 124gr will work okay (sufficient velocity and expansion) out of my 3.25" barrel out to reasonable distances (<15 yards). If I'm not making a good assumption, please let me know.

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As long as it functions in your gun (which you should test) you are good to go. No handgun round will be an instant manstopper, and you will not gain much (if anything) from the short barrel version. If your gun and you as the shooter can handle it, +P is hardly ever a bad idea. Velocity aids in expansion, but the Gold Dot is a good bullet, and even at standard pressures expands reliably.

Good to know; works for me. So, I'll assume that my current stock of Speer GDHP 124gr will work okay (sufficient velocity and expansion) out of my 3.25" barrel out to reasonable distances (<15 yards).

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That's a safe assumption. I've found the 124 grain standard pressure GD to expand just fine out of 3" barrels. Not quite as much as 4" and 5" but plenty enough to matter. There's no need to rush out and find a new carry load any time soon.

The next case I buy, I'll consider the Speer GDHP Short Barrel version (or the +P version -- not sure what the difference is yet) or some equivalent round.

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I think the short barreled version is a problem looking for a solution. I'd stick with either the standard pressure or +P load.

I carry +p127 ranger loads in my glock 19 and it works well system wise The reason i picked this load is its very close to the .357 125 grain load that is IMO the best documented stopping load. I don't have a .357 sig , and the 127 load is just carry not practice. The 9mm is a lot cheaper to shoot paper targets


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