About Cartridge Maximum Pressures

3

3006loader

New member
Why are cartridges rated to a maximum pressure if the main thing you should worry about from loading over max charge is the gun blowing up? Shouldn't the guns themselves be rated for that pressure? Can you go slightly over a maximum pressure for a given cartridge as long as the gun can handle it? Or are all guns rated to the maximum pressure of the cartridge they fire?

An Example: .38 special is rated to 17000 PSI. If I have a gun that shoots both .38 special and .357 magnum (35,000 PSI max.), then could I load the .38 Special to around 25,000 PSI and still have it be safe, or does something happen specifically to the brass in over pressure situations?

I know reloading can be dangerous so I will always stay in the recommended loads (I like my guns), but was just curious about this.
 
I have tried to blow guns up.
My father was a gun designer, and I was a gun destroyer. He forgave me when he saw my documentation.

There is an important fork in the road:
Is the gun stronger than the brass?
If the gun is stronger than the brass, then I can work up incrementally until the brass is just starting to fail, back off a safety margin and have a hot load.
But if the gun is not as strong as the brass.... and 38 special brass has no trouble with 85 kpsi and the 38 special chamber walls re 0.065" thick, then I can work up until I get split cylinders and broken top straps.

What does it all mean?
You need to use published loads in 38 specials and forget about thinking about pressure.
 

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Why are cartridges rated to a maximum pressure if the main thing you should worry about from loading over max charge is the gun blowing up?
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I hear it all the time; I am told the Japanese rifle is the strongest rifle in the world. And I always say when I hear that I say forget the rifle; give me those Japanese cases. If the case did not blow up under all that abuse the case must be the strongest cases in the world. And no one has a clue because they claim they are soooo confused.

I have tested receivers that were sold as suspect; when testing the suspect rifles I found the case heads crushed, shortened and got larger in diameter, I know that because I am the only one that measure before firing and again after firing. And then there are those primers; when testing receivers I find the primer pockets open up to the point the case can only be fired once. After that I find testing receivers with work hardened cases is a bad habit. When I test a receiver I insist on using cases heads that are not work hardened.

F. Guffey
 
You have cartridges that were introduced when the guns where of quesgtionable metallurgy (32 S&W, 38 Spec. 38 S&W, 44 Spec). Many cartridges where for guns of weaker designs (recently the 32 H&R comes to mind).

Are there guns that are far more capable that these cartridges can be fed to? Of course; and if you can GUARANTEE that this ammo won't end up in a weaker firearm you can hot load. But if you load 38 Spec to a Keith load and your friend stuffs it into his S&W Model 12 and it grenades on him; expect your friendship to be over right then and there.
 
maybe what you need to hear is that firearms can be designed to work only within the limitations of the ammunition. As was said, a cartridge case will fail if you pack too much pressure into it. It's pointless to build an artillery strong rifle to fire a standard brass cartridge. Regardless of how strong the gun is, that round might blow out.

Pistols are engineered to be capabable of handling a certain load. Bigger and stronger means that they can handle more power.

So, these firearms are designed to handle a certain level of power and pressure, and then we must keep the power and pressure of the loads within the design limits of the gun.

Keep in mind that pressure isn't everything. It has to balance with the strength of the steel, the design, etc.
 
3006loader

Posts #4 and #5 understood the question. Thank you for your responses!
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ooo I am post #2 and did not make the list:(

I will have to work on my reading comprehension.... when I get over the rejection:(
 
Maximum Pressure is a design constraint to keep the firearm working.

The pistons and cylinders in the engine in your car are designed to handle the energy of a fuel/air mixture that undergoes a chemical reaction. It is designed to work at those pressures for years if necessary. One single detonation of pure Nitrous Oxide mix in the exact same cylinder will destroy the machine.

Proof Loads have about 30% more pressure than max average pressure loads (give or take on the cartridge). A standard diet of proof load pressure cartridges is a sure way to destroy a firearm even if you don't blow up the gun. Lugs will get set back, steel will start to sheer. It is the equivalent of adding "just a little bit" of Nitrous Oxide to your engine, it rapidly accelerates the wear and tear.

So that is why cartridges have Max Pressures, so ensure the firearm remains usable throughout the service life. Exceed max pressure and service life degrades rapidly, until something fails, breaks, or the gun blows up from repeated fatigue stresses.

Jimro
 
ooo I am post #2 and did not make the list

I will have to work on my reading comprehension.... when I get over the rejection
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Clark, nothing wrong with your reading comprehension; you have no way of knowing if 3006loader had preconceived answers and then there is the possibility he prearranged the outcome before he posted the question.

I DO NOT KNOW! I do not know if your answer influenced;

Posts #4 and #5 understood the question. Thank you for your responses!
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I do know the case is the limiting factor; if the case was not the limiting factor there would be no need for 'HATCHER HOLES' and then there are subjects talked about on the INTERNET, one being 'gas handling capability'.

Like Randy Newman said: And here is a little New Orleans tune;

http://thefiringline.com/forums/showthread.php?t=341348

F. Guffey
 
I know reloading can be dangerous so I will always stay in the recommended loads (I like my guns), but was just curious about this.
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Nothing wrong with my comprehension, there are times I do not see 'it'. Were you curious, in my opinion based on my experience you turned your curiosity into something that appears personal.

One day I was in Fort Hood, a few troops ran up to me and said they were separated from their money. I had to ask; how, when where? And how could you allow something like that to happen?

They explained the separation happened when the left the Lateran. They claimed there were troops there that wanted to go to town and needed the money. There was nothing for me to do but go get in line. It went something like; "If you will lend me some money I will be your friend" and I said "If I have to lend to be a friend then friendship comes to high". Anyhow, we all got our money’s worth.

F. Guffey
 
Not a new concept. The 38/44 cartridge was designed to give 357 mag performance in 38 Special cases. The loads were intended to only be fired in larger 38 special revolvers built on the 44 special frame. But people started shooting them in smaller framed revolvers and blowing them up. This led to the 357 magnum. The cartridge is slightly longer primarily to prevent it from being chambered in 38 Special guns.
 
Guffey,
I give remedial lessons to other engineers on how to be funny.
I took the OP's faux pas and ran with it.
 
A little over maximum may expand the primer pockets after a few loadings. Or the brass may fail.
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HOW DO YOU DO THAT! ?

Clark and I were left:eek: with the feeling there was something wrong with our reading comprehension. And now? You come along claiming you can expand the primer pocket without shortening the case head from the top of the cup above the web to the case head and you can do all of that without expanding the case head and then there is that other part that is never considered; the flash hole.

I could go further into other effects but there is a limiting factor; the limiting factor?

F. Guffey
 
There are times, like now, when I really enjoy this forum. For some reason, I have to admit that I like that Clark likes to blow things up, and runs his loads on the ragged edge of 'too much'. It's interesting to me, and maybe that's because I'm also an engineer but am too conservative to push the limits like Clark does. And F Guffey also interests me a lot. Took me a while to understand what he was saying. Then I finally realized that a fellow needs to be a pretty knowledgable reloader just to get to the place where Mr Guffey starts to make sense.

I've been running my big chainsaw all morning, and this is way more fun than that. Thanks, guys...
 
You bunch of whiners. I may not have gotten every single syllable right but I managed to tell him what he wanted to know.
 
yea yea yea :p

You can flip that around. We are seeing amazingly light rifles now.

So, as we are stuck with maximum pressures because those slackers of yore could not make a decent gun, they are no making them incredibly light and still resist that pressure.

You might also need to be aware that blowing up a gun is not the only impact, you can stretch the receiver and or bolts damaging it.

Safer than a blow up but still a useless gun.
 
I was reading at a tenth grade level in third grade, never wrote anything that earned less than an A, had two essays submitted to an arts journal when in art 101,have had a number of short articles published in glossy print, and made a living for years editing garbage into eloquent prose.
 
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