Why aren't there more +P loads?

I have been reloading for years and typically do a lot of checking prior to getting busy at the bench. However, I have found that most load data is falling far short of the SAAMI specs for a given round in the pressure dept.

Why are the max loads 10-12,000 psi short of design?

How much farther above listed data will you go without having a pressure sensor of some kind?

BigNate,
What loads are you looking at that run 10k under max? +P loads are over saami normal max, not at it as is sometimes thought. The 257 Roberts for example has a saami max of 45,000 cup, in its +p load the max is 50,000 cup a 5000 cup industry excepted overload.

The max you see printed is normally the AVG max, NOT the max ALLOWED pressure for that cartridge. The load printed could have a swing of 5000 +/- of the max allowed and would be shown as being at 5000 under pressure. Then subtract a few psi for safty reasons and you "appear" to be under pressure.

Then too don`t forget our friends the lawyers

FWIW, I won`t go over the listed data in the manuals for any cartridge. You don`t gain enough to make the risk worthwhile. If I need to drive a given bullet faster than the cartridge I have is doing, I`ll buy a bigger rifle.

[ 06-13-2003, 19:44: Message edited by: Ol` Joe ]

You will usually find "+P" loads for those cartridges which were developed long, long ago. The reason being that the steels used in firearms 100 years ago were not of the quality used today.

The more recent cartridges take into consideration the better quality of metals used, and therefore do not have "+P" or "+P+" loadings.

"+P" generally indicates a load that is 10% higher than the original standard rating, and "+P+" indicates 20%.

Unless you have a new firearm in excellent condition, stick with the standard loads...

I have incrementally overloaded the following cartridges to see what gives; .223, .243, 25acp, 257 Roberts AI, 32acp, 32sw, 32S&W Long, 32-20, 7.62x25mm, 7.62x54R, 8x57mm, 9x19mm, 9x23mm, 357 Sig, 38 sp, 357 mag, 38sw, 40sw, 10mm, 10.4mm, 45acp, 45Colt, 452/70, .410, and 45/70.

Two of the real stand outs in large safety margins are 9x19mm [Luger] and 38 Special. These are the same cartridges offered in +P and +P+ by large corporations with take no risk mentality.

If 9mm can shoot 60% extra powder and 38 sp 140%, where is the risk in selling ammo with 10% extra powder [20% extra pressure] and calling it "+P+"?

[ 06-14-2003, 00:55: Message edited by: Clark ]

Clark

Are you going to guarantee that every model of gun ever manufactured for a caliber can take your "+P+" loads? That is the problem the big ammo manufacturers are facing. Small specialty ammo manufacturers like Buffalo Bore will greatly exceed a pressure limit for old time cartridges like 45 Colt or 45-70 - but they also specify which guns can fire these higher pressure rounds. The bigger, more generic ammo manufacturers simply don't see the relatively small amount of profit possible as being worth the risk of one of these cartridges being fired from an old Colt Single-Action or Trapdoor Springfield.

Will your "+P+" 9mm fire safely from an old no-name Spanish "copy" of a Browning Hi-Power? Will a Colt New Army made in 1900 (when heat-treating was done by "color" and the temperature gauge ignored or non-existant) handle your +P+ 38 Special loads? I agree, handloading for a specific, strong modern firearm lets many of these old cartridges gain significant power gains. And some modern cartridges too, it's amazing how powerful a 32 H&R Magnum is when loaded to 35,000 psi for a S&W K-frame Model 16-4, instead of the SAAMI 20,000 psi for break top H&R revolvers. But shooting that 35,000 psi load that's safe in the S&W will instantly & permanently disassemble that H&R revolver.

[ 06-15-2003, 07:27: Message edited by: CMcDermott ]

I have a Hornady, Nosler, and Speer manual none of which indicate load pressures. On IMR's web page they list loads for a 150gr. in the 7mm Rem Mag only up to 52,000 which is 9000 below SAAMI specs. The VihtaVuori web page doesn't list pressures. Hodgdon does list pressure but most are around 50,000 cup.
With Hodgdon making powders that are less sensitive to temperature swings I figured the 5,000 cup margin would still allow for higher pressure loads than listed.
I would be willing to nudge this margin especially with a modern rifle comparable to other cartridges in the same type rifle that have a higher pressure round chambered.

CMcDermott,

"Are you going to guarantee that every model of gun ever manufactured for a caliber can take your "+P+" loads?"

I don't guarantee anything, I am just trying to find out how big the safety margins are. I want more information than I can get from load books [except Ackley's].

"Will your "+P+" 9mm fire safely from an old no-name Spanish "copy" of a Browning Hi-Power?"

I have not tested either.

"Will a Colt New Army made in 1900 (when heat-treating was done by "color" and the temperature gauge ignored or non-existant) handle your +P+ 38 Special loads?"

I have a Colt new army that just says "38 caliber" on the barrel. I have gone past 357 mag loads with it. The OAL is slightly less.

"I agree, handloading for a specific, strong modern firearm lets many of these old cartridges gain significant power gains. And some modern cartridges too, it's amazing how powerful a 32 H&R Magnum is when loaded to 35,000 psi for a S&W K-frame Model 16-4, instead of the SAAMI 20,000 psi for break top H&R revolvers. But shooting that 35,000 psi load that's safe in the S&W will instantly & permanently disassemble that H&R revolver."

I have overloaded a couple 90 year old 32 S&W Long Colt Pocket Positive revolvers with loads in excess of 32 H&R mag. The weak spot is the forcing cone. The forcing cone will not last too long if the cases stick. The forcing cones can be TIG welded and turned on a lathe to make them much stronger than before the failure.

But back to 9mm and 38 sp:

I have tested a Star M43, Tokarev, Glock 19, and Kel-Tec P11 all in 9mm. The 65% extra powder causes the case to bulge. Sometimes I can go further:
P11, RP primed brass, 158 gr XTP, 1.169", 11 gr Power Pistol.

I have tested an RG [Aluminum], Colt Police Positive, S&W 60, and Colt Agent [Aluminum] all 38 Specials.
The weakest 38 sp was the Colt Agent, that bent the frame at 140% extra powder [but still shoots]. My favorite is the 5 Colt Police Positives I bought for destructive test. I reamed one out to 357 mag and have shot hundreds of rounds of 26 gr LIL'GUN and 158 gr LSWC. This kicks so hard, no published 357 mag load comes close.

[ 06-15-2003, 09:27: Message edited by: Clark ]

Ricciardelli, I have reviewed your reloading pages and have noted that data you have posted as the range of loadings from lowest to highest often exceede the listed or published max.

Other than just working up slowly, and inspecting the cases how do you know when to stop? Can you measure pressures at home? If the cases don't reflect excessive pressures is there a way to calculate the change in charge = x amount in pressure?

I typically start below listed max and work up until I get some indication of higher pressures and then back off just a bit. Using this method I have worked up loads safely for many different loads without a problem. I am most interested in the pressures as SAAMI lists a max that isn't even approached in load manuals.

BigNate,

What specific "indications" do you use.

I find that the "Ken Waters" case expansion method is the best available since I don't have a strain gauge mounted on every barrel. All other methods might be explained by other factors.

All of Steve's data that I've looked at is book max, one book or another. Which manual are you comparing to?

Hobie, Guess I'm not sure what the "Ken Waters" method is. I usually just look for the standard visual indications until I'm close to listed max and then I measure the case at the web.

Ol` Joe,
I just shoot incremental overload work ups in pistols. [I also do shoot rifles for accuracy]

I measure peak pressure with it's effect on primers, brass, and guns.
I measure average pressure [from ignition to bullet escaping barrel] with recoil.

This has no validity to the SAAMI point of view.

I have been doing this for years. It seems important to do and talk about to me. This week I was working on a Tokarev pistol with a 9mm Chinese barrel reamed out to 9x23mm with additional throat for 158 gr XTP bullets. I was shooting 12 gr of Power Pistol at 1.35", Starline 9mm supercomp brass, wspm, but the cases would alway blow out:
http://www.thehighroad.org/attachment.php?s=&postid=322911
Today I tried Winchester 9x23mmWin primed brass and I got up to 16 gr and the gun shot just fine. That was a good place to quit because the powder takes a number of extra steps to double compress into a small volume and not squish the bullet. The Alliant max load for 357 mag is 8 gr, 158 gr, 1.59" and I am happy to reach the 100% overload level at a shorter over all length.