Pushing the limits of a GP100

[Super Sneaky Steve]

I was wondering if anyone on this forum has pushed a GP100 beyond published data. I know the gun can handle it and there may not be a real practical reason for doing this, but I'd like to see how fast it could push say a 180gr XTP.

13.5gr of H110 got me a 1106fps out of my 6" barrel and didn't feel very eventful when shooting it. Has anyone done something hotter?

I need a better round for zombie bears. You know, just in case.

[Edward429451]

Tag

(I only have experience with the RH's and SBH's)

[jmorris]

Most folks don't publish loads they use that are beyond "book" data. I have pushed 180's quite a bit faster than that out of contenders and lever action carbines though and the loads were not over published data.

[Mike Irwin]

Anyone who wants to discuss this subject, especially particular loads that may exceed published specifications, MUST read the following:

http://thefiringline.com/forums/showthread.php?t=147679

[savagelover]

while it wasn't a Ruger,,,I seen a guy try that with a Smith-Wesson...in 357 cal...Not sure what bullet he was using...But the results where out of sight as they say....No top strap left.rear sight was out of sight,lol
And a 3 piece cylinder....My God it was loud....Damn lucky no one was hurt...You should have seen the look on his face...I think it was an over charge of Bullseye powder,but he claims not.....So go ahead and push it if your that crazy...

[LAH]

The Hodgdens site won't give you over 13.5 grains of H-110 for a 180 grain. Nosler Part. They say 1396 FPS @ 39,100 CUP.

If your published load won't do what you want done you may want to change the load or use another caliber. For a big load in my Ruger BHB 357 is use the Lyman 358429 with H-110.

Be careful out there.

[PA-Joe]

The other issue is that you cannot control where that ammo ends up and in which gun. It may work in the Rugers but what happens at the range when you put it into another gun.

[arch308]

IMO that's a bad idea. Not only is what you are doing dangerous but is hard on the gun. I NEVER go beyond published data! NEVER!

[zxcvbob]

If you had a Freedom Arms 5-shooter, there's data available. But you don't, so don't even think about it. If you can find CIP load data instead of SAAMI, that should be OK.

[SL1]

Prior to SAAMI accepting standards in psi, they used CUP to set peak pressure standards. Not only do these different standards have different numerical values for the .357 Magnum (35,000 psi vs 46,000 CUP), they actually do NOT produce the same real pressures. That is obvious from looking at the maximum loads for various powders and the resulting velocities with identical bullets in successive editions of reloading manuals from the bullet manufacturers. Clearly, the CUP data is substantially faster.

The GP100, and its predecessor, the Security Six, were both designed during the CUP days. So, looking for some data from old manuals will give you SOME idea of how hot the old CUP loads were that were considered safe in those guns. HOWEVER, some of the powders have been reformulated enough that their load data did change somewhat, too. So, using old data with new lots of those powders in not without risk.

I frankly think that SAAMI did the shooting public a disservice by down-loading the .357 and .44 magnums because they are just INVITING handloaders to experiment to try to regain the original performance in guns that were designed for the original standard. Perhaps some day, SAAMI will come-up with "+P" standards for those two cartridges that will restore their performance levels to what people bought them to do.

But, in the mean time, whatever you do, work-up loads SLOWLY, and, if you get pressure signs like sticky extraction, BACK OFF and don't go there again.

SL1

[Slamfire]

I frankly think that SAAMI did the shooting public a disservice by down-loading the .357 and .44 magnums because they are just INVITING handloaders to experiment to try to regain the original performance in guns that were designed for the original standard. Perhaps some day, SAAMI will come-up with "+P" standards for those two cartridges that will restore their performance levels to what people bought them to do.

Gun companies will not tell you what they designed their firearms, because they know people will try to load to that limit. The liability is too high.

In so far as loading data being light, might be due to better measuring equipment. The older loading manuals, the data was created by looking at physical signs, such as primers, case expansion, cases sticking.

Those really don't tell you what the pressures are.

For those who want to push the envelope, remember that stronger does not mean unbreakable.

[zxcvbob]

I think with the Speer #8 manual, they kept adding powder until the gun blew up, then backed off a tenth and called it good.

[JohnKSa]

But, in the mean time, whatever you do, work-up loads SLOWLY, and, if you get pressure signs like sticky extraction, BACK OFF and don't go there again.

Pressure signs in revolvers are not as consistent or as easy to read as in rifles. It's not usually a good idea to keep pushing a revolver load hotter while looking for pressure signs.

[SL1]

1. To JohmKSa:

I was not advocating pushing revolver loads until you see pressure signs, so the quote is somewhat out of context. I was cautioning that working-up loads to old data with new powders MIGHT cause more deviation from the data than normal due to reformulations of the powder since the data were developed. I theory, any powder reformulations SHOULD not exceed the lot-to-lot limits SAAMI adopted unless the powder is renamed, so the work-ups should be the same with old or new data IN THEORY. However, those pressure limits are pretty wide in the first place, so you should ALWAYS work-up loads when changing powder lots. However, there have been too many posts here recently where somebody was starting in the middle, instead of at "start," so I wanted to say something about working-up.

I agree that pressure signs in revolvers are not very reliable. However, the OP's gun is a strong model that is not LIKELY to blow-up if he stays within the data. In other guns, such as old COLT .45s, the design pressure is so low that the first pressure sign may very well be the gun blowing-up.

2. To Slamfire:

You wrote "Gun companies will not tell you what they designed their firearms, because they know people will try to load to that limit. The liability is too high."

While that is true, it is also true that gun companies WILL tell you whether their guns are suitable for "+P" ammo IF THERE IS A SAAMI SPEC for +P ammo for the cartridge that their guns chamber. That is why I am advocating a +P standard for the .357 Magnum and .44 Magnum in the SAAMI "psi" standard. There is such an obvious performance difference between the old SAAMI "CUP" and new "psi" standards that I don't think there is any reasonable excuse for NOT having a +P standard under the psi version. Clearly guns were not blowing-up under the old CUP standard with factory ammo.

SL1

[Brian Pfleuger]

Are not all "SAAMI compliant" firearms required to proof at 20% over max listed pressure?

(Not sure SAAMI compliant is technically the correct term)

[Edward429451]

I frankly think that SAAMI did the shooting public a disservice by down-loading the .357 and .44 magnums because they are just INVITING handloaders to experiment to try to regain the original performance in guns that were designed for the original standard. Perhaps some day, SAAMI will come-up with "+P" standards for those two cartridges that will restore their performance levels to what people bought them to do.

Are you implying that I can not trust what is listed as a pressure reading for cartridges in my load books? That they are outright lies and we can safely go further than max?

[jaysouth]

Supersneakysteve,

Send your Ruger pistol to me and my brother bubba. We will PM you with the load data that we blew it up with.

Send a case of bud light to help us in our experimentation. Send two!

[RalphS]

Marshall Stanton of Beartooth Bullets publishes a load for his 185 grain WFNGC Hardcast bullets. Look it up on his website if you're interested.

It's a very hot load. I've shot a few of these in my GP-100 and it didn't blow up but I wouldn't go any further with it and probably won't ever use it because if I need a load that hot, I'll carry my Redhawk 45 instead.

It averages 1293 fps out of my 4 inch GP-100.

With the 180 grain Missouri Bullet, I get 1319 fps with the same load.

Do not use this load for the XTP. It's a hardcast load.

[JohnKSa]

I was not advocating pushing revolver loads until you see pressure signs, so the quote is somewhat out of context. ... However, the OP's gun is a strong model that is not LIKELY to blow-up if he stays within the data.

The OP's post was explicitly asking about "pushing a GP100 beyond published data", so I assumed that yours was in the same context.

[zxcvbob]

Are you implying that I can not trust what is listed as a pressure reading for cartridges in my load books? That they are outright lies and we can safely go further than max?

You can generally trust that they are safe. But there is some disagreement about what "max" means. SAAMI keeps changing the standards, and there is a competing standard in Europe called "CIP" that has quite a bit higher maximum pressures.

There are some older manuals that used dubious testing methods that have very hot loads that may actually not be safe.

[SL1]

What I pointed out was that there are different "max" loads, with PRESSURE TESTED DATA based on different standards, two of which come from the same organization - SAAMI.

The old CUP standard was less accurate than the new psi standard, but it was not a "dubious method." Guns were designed and ammunition was loaded by factories for decades using that method, and it was not blowing-up guns. Pressure-tested load data based on CUP methods should not be confused with some of the early handloading manuals that did NOT pressure test their data by the copper-crusher method, but instead used MUCH less reliable methods such as loading up to sticky extraction and backing-off a small amount.

So, if a GP-100 is designed for ammo loaded to the CUP standard, and the CUP standard is STILL an accepted standard, then it does NOT suddenly become unsafe to use those loads in that gun just because SAAMI adopted an ADDITIONAL standard that results in lower max loads.

On the other hand, once SAAMI adopted the lower standard, new guns may have been designed to be safe only with the weaker ammo. For example, I would not want to shoot a 46,000 CUP load in a Ruger LCR, even though I have shot them in a Ruger GP-100 with no ill effect.

So, I will stand by my original post, which was that the OP might get some SAFE hotter loads by looking for CUP data in older manuals, rather than just experimenting on his own. And, I threw in that the NORMAL concept of working-up a load is especially important when using old data, because powders have sometimes been reformulated since then.

But, I still blame SAAMI for creating the situation where a cartridge that was designed to produce 1500 fps with a 158 grain bullet from a 8-3/8" barrel is now not able to produce more than 1250 fps from a 6" barrel. The only way I see to get out of that situation now is to provide a +P standard that is equivalent to the old CUP standard in terms of the actual pressure. (Yes, I realize that CUP numbers are not identical to psi numbers for the same actual peak pressure.)

SL1

[drail]

Even if you don't "blow" your gun (any brand) you are subjecting it to forces it was never designed to deal with. It is simple abuse. When I was young and dumb and first started reloading I did what so many new reloaders do - push the envelope. Don't do this. You will not gain anything. You will almost surely shorten the life of your gun. By loading heavy charges of a popular powder under lighter weight bullets I managed to completely erode the forcing cone of a nice GP 100 in a very short period (like a couple of months). It looks exactly like I took a oxy-acetylene cutting torch to it. Only fix is a new barrel. This load came straight out of the Speer No 11 manual. It's been dropped in the newer editions. Was it a safe load? Probably. The gun never blew. Was it a dumb thing to do? Absolutely. Stick with mid range to warm loads and leave the extreme upper limit stuff to the guys who just want to show off at the range. Unless you like buying new guns. Even guns that are totally overbuilt like a Ruger will have their usable service life shortened from firing enough max. loads. If you really believe you "need" more ballistic energy from a gun trade it and buy a larger caliber.

[zxcvbob]

The old CUP standard was less accurate than the new psi standard, but it was not a "dubious method." Guns were designed and ammunition was loaded by factories for decades using that method, and it was not blowing-up guns. Pressure-tested load data based on CUP methods should not be confused with some of the early handloading manuals that did NOT pressure test their data by the copper-crusher method, but instead used MUCH less reliable methods such as loading up to sticky extraction and backing-off a small amount.

"Dubious methods" is whatever they did to come up with the data in Speer #8. Perhaps they tested in cold weather only? Something's not right with that book.

[jmorris]

It's a very hot load. I've shot a few of these in my GP-100 and it didn't blow up but I wouldn't go any further with it and probably won't ever use it because if I need a load that hot, I'll carry my Redhawk 45 instead.

+1. I paid for my first 357 at 13 and started loading shortly after that, so I'll admit to working up to loads beyond some book data. Now that I have wiskers and maybe lazy or simply have a risk meter (I used to be invencible) I just use a more powerful round.

It took me months back then to work up 357's to almost 41 mag levels. These days it would take me 5 minutes to down load a 44 mag to the same power level. Not very dramatic but I like life that way.

[Don P]

but I'd like to see how fast it could push say a 180gr XTP.

13.5gr of H110 got me a 1106fps out of my 6" barrel and didn't feel very eventful when shooting it. Has anyone done something hotter?

Keep adding powder until it blows up, and then you will know the limit of the GP-100. Keep track of your data so you know when and how much powder it took to do so and adjust from there.