cartridge pressures
- Thread starter bingo1010
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But a different cartridge right? if yes , you gone and answered it yourself 
Cocked&Locked
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as mentioned, not all cartridges are created equal , some are thicker walled then others. Also, (more in handgun cartridges) some have more support in the chamber then others. As long as it's supported, it can't go anywhere ( i know there is material flow but it's less the a percent unless you've got HUGE pressures. Most metals won't fail in compression, only tension. Seperations occur only after you've stretched the case by repeated firings or in a inproperly headspaced (read support) chamber condition.
My two cents worth, I'm sure others will expand on it
D
, some are thicker walled then others. Also, (more in handgun cartridges) some have more support in the chamber then others. As long as it's supported, it can't go anywhere ( i know there is material flow but it's less the a percent unless you've got HUGE pressures. Most metals won't fail in compression, only tension. Seperations occur only after you've stretched the case by repeated firings or in a inproperly headspaced (read support) chamber condition. My two cents worth, I'm sure others will expand on it
D
That is the way that they are designed. Max for any cartridge manufactured today is about65,000 psi. Most older cartridges are lower then that.
Different considerations come into it. For example, manufactures of cartridges for militry purposes would palace reliabilty of extraction and operation above other considerations. Targert shoters, accuracy.
The dangerious game hunters of africa, possibilty penetration and bullet performace.
Each has it's place in cartridge manufacturing.
Different considerations come into it. For example, manufactures of cartridges for militry purposes would palace reliabilty of extraction and operation above other considerations. Targert shoters, accuracy.
The dangerious game hunters of africa, possibilty penetration and bullet performace.
Each has it's place in cartridge manufacturing.
A lot of other factors come into play, for instance air space, weight of bullet, and even one grain more of powder.
An example from the reload manual I have.
257 Remington Roberts Never exceed 48 grains of H335 powder pushing a 60 gr bullet pressure units 53824
Same caliber and different powder and bullet weight
Never exceed 37 grains of Accur 2520 powder pushing a 90 gr bullet - pressure units 43500
Now same 90 gr weight bullet using H335 powder again is never exceed 43 grains. And pressure units go back up to 51504
It's not the the different cartridge size so much, but the "recipe" for the right mix. You can actually liquify the brass.
BTW, don't use those reload values, I didn't state what brand of bullets they were as well I could have done a typo
An example from the reload manual I have.
257 Remington Roberts Never exceed 48 grains of H335 powder pushing a 60 gr bullet pressure units 53824
Same caliber and different powder and bullet weight
Never exceed 37 grains of Accur 2520 powder pushing a 90 gr bullet - pressure units 43500
Now same 90 gr weight bullet using H335 powder again is never exceed 43 grains. And pressure units go back up to 51504
It's not the the different cartridge size so much, but the "recipe" for the right mix. You can actually liquify the brass.
BTW, don't use those reload values, I didn't state what brand of bullets they were as well I could have done a typo
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No hard and fast rules. It's pretty much up to the company that first starts making rifles or ammo for it. Firearms designs often determine the pressures of the ammuniton made for them. This often sets the standard for the cartridge at introduction.
Hey farmnut, you didn't read bigo's frigging question did you, he wanted to know why the SAME ACTION <-- note SAME add ACTION to that had different pressures for different calibers.
So to me , he wanted to know why the SAME ACTION could handle , lets say , a 338WM could produce 68000 on the SAME ACTION, yet in a 30-06 on the SAME ACTION might only be 55000 on the SAME ACTION
So to me , he wanted to know why the SAME ACTION could handle , lets say , a 338WM could produce 68000 on the SAME ACTION, yet in a 30-06 on the SAME ACTION might only be 55000 on the SAME ACTION
Unforgiven said:
.
To answer your question, because some rifles chambered for 30-06
would puke and come apart at 68000.
Cartridge companies load for the weakest denominator, same
for reloading manuals.
Sure a Remington 700 can handle higher pressure 30-06 then
SAAMI standard of 50,000 cup but a lot can't.
Pressure is set for the cartridge not the rifle.
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Ardent
CGN Ultra frequent flyer
farmnut said:
Who pissed in your cornflakes this morning? Learn to be more polite, or you will not be received well nor last long here.
The comments above yours are correct, brass makes a huge difference. WSSM brass, 65,000psi brass, is MUCH thicker than 50,000psi commercial brass for say a 6.5x55.
Your comments about the "weakest link" are only part correct. This effect is true for some cartridges much more so than others, like the .45-70. But, with a modern cartridge, this "weakest link" sentiment is BS. The loads are loaded to a standard pressure limit, and the rifle builders design with that in mind, not the other way around.
farmnut said:
Thats the gist of it alright. Hence why you go to the store and buy 45/70 ammo its loaded to trapdoor pressures....Cause of the millions of 45/70's out there theres still a couple trapdoors kicking around...This is why so many people who have shot factory for years,then get into reloading are so dismayed when they run a factory load over their new chronograph
bingo1010 said:how can some cart. operate at 45 000 psi others at 55 000 and still others at 65 000, all in the same action and all using the same material( brass )
Because they weren't necessarily designed with a particular rifle in mind, more of a worst case seniario deal.
For instance while the .270 is designed for higher pressure than a 30-06, when both are used in the same modern rifle there's no reason the 06 couldn't be loaded to the same pressure as the 270, after all even the brass is of the same strength.
Now lets consider the factory under-loaded .280 vs the .270
Cocked&Locked
CGN Ultra frequent flyer
- Location
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farmnut said:
gee, such a subtle and well reasoned add on to the discussion! Maybe you should become a UN ambasador or a statesman of some sort
Ardent said:
I am so miserable I piss in my own coffee.
65000psi brass? I don't think such a animal exists,
because I would be the first one making 65000psi
brass for 6.5X55 and all the Swedish Mauser shooters
out there would make me a rich man.
And your MUCH thicker brass might be just a few
thousands of a inch, don't think that makes much
difference on how much pressure a rifle can handle.
Only place brass thickness and strength makes difference
is in firearms that don't fully support the cartridge
head. Some semi auto pistols and certain milsurp rifles.
"gee, such a subtle and well reasoned add on to the discussion! Maybe you should become a UN ambasador or a statesman of some sort."
So you think I would make a good politician, humm at my age I did not consider
a career change.
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Ardent
CGN Ultra frequent flyer
farmnut said:
Well, here you are wrong. The case head on a WSSM case IS much thicker than the case head of a 6.5x55, and yes it does make a difference in guns other than pistols etc. Infact, WSSM brass for instance frequently and routinely operates at 63,000+psi, just check a reloading manual.
Here's from Hodgdon's:
Ardent I agree with you that modern supper Popper ultra whizbang
cartridges operate at higher pressure, but that's because they are
chambered in modern actions that can handle it.
That don't mean that you can re barrel a old Swedish Mauser to one
of them and expect the thicker brass to hold the rifle together.
Purpose of the cartridge case is two fold:
1st. As a convenient envelope to hold all the components together, primer,
powder and bullet.
2nd. As a high pressure chamber seal.
It contributes next to nothing to how much pressure a RIFLE con handle.
cartridges operate at higher pressure, but that's because they are
chambered in modern actions that can handle it.
That don't mean that you can re barrel a old Swedish Mauser to one
of them and expect the thicker brass to hold the rifle together.
Purpose of the cartridge case is two fold:
1st. As a convenient envelope to hold all the components together, primer,
powder and bullet.
2nd. As a high pressure chamber seal.
It contributes next to nothing to how much pressure a RIFLE con handle.
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To find an example of the brass not being the deciding factor, you need to look no further than the 300WM. Factory loading for the first 10 or so years of it's existance with 180gr bullets was 3070fps. In 1972-3 it was downloaded to 2960fps where it remains today. There are a few examples of new ammo that excedes this but I don't think any get back to the original loading.
So is that because they started making weaker brass? Or because some actions can't handle the pressure ?
So is that because they started making weaker brass? Or because some actions can't handle the pressure ?
joe-nwt said:
No. Brass is the weakest link in strong action.
It has to be flexible to seal the chamber and not
split, yet hard enough not to flow in to the bolt and
the extractor cut, unsupported part of the head
expands, primer pocket loosens.
May be the the original loading was at the limit of the brass,
otherwise they would have designed a stronger case instead of reducing
velocity hence less pressure.
so if the wsm cart. operate at 65 000 and the 300 win at 54 000 both in the rem 700 action clearly the action is not limiting the 300 win the brass is...no? so the question becomes why does someone not make +P brass for the 300 win that can operate at 65 000 like that of the wsm?
