I cannot find the information about pressure.

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Archie

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SAAMI has a list of cartridges and the maximum pressures recommended.

The question is, are those pressures firearm dependent?

F'instance, several cartridges - I can think of the 7x57mm Mauser, the .257 Roberts and the (Super) .38 Automatic - that show "+p" loads in newer arms or stronger actions.

I am also aware a manually operated arm is more suited to more powders than gas operated arms.

Also aware some cartridge cases will not tolerate higher pressures - some early .45-70 cases were limited. I have a currently manufactured CZ small '98 Mauser type bolt rifle chambered in 7.62x39mm. However, all loading manuals seem to use some version of AK 47 as the test rifle.

The bolt gun should comfortably accept pressure greater than that of an SKS or AK. Not twice as much, of course, but some specific - small - percentage.

Now I'm sure some well meaning but lacking individual will tell me I'll kill myself. Or at least blow up my rifle. Thanks anyway.

Does anyone have real information or know where it can be found?
 
SAAMI specs for cartridges are the standard for all applications.
But if a firearm manufacturer's design deviates from being able to accommodate those standards, then you have a problem.

Case in point: some nitwit inserts a SAAMI-rated 30-06 cartridge into a piece of molded PVC pipe and calls it "bargain rifle"
 
SAAMI has a list of cartridges and the maximum pressures recommended.

The question is, are those pressures firearm dependent?

No.


Does anyone have real information or know where it can be found?

The 'real' information is the SAAMI specifications. Firearms are built to operate safely with ammunition loaded within SAAMI specifications.
 
A cartridge stamped +P is loaded to produce higher pressure (and velocity). Firing +P ammunition in any firearm chambered for those cartridges will produce higher pressure than firing non-+P ammunition of the same cartridge.

For safety, verification that a given firearm is rated to handle +P ammunition is required before using it in the firearm.
 
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If you have a forign made firearm your standard may be CIP vs SAMI. The pressure may be less as their standard has legal implications.
 
SAAMI has a list of cartridges and the maximum pressures recommended.

The question is, are those pressures firearm dependent?

They are cartridge dependent. +P isn’t a given pressure just an indicator that the ammunition is over pressure for the cartridge. It’s not even a consistent amount/percentage over their standard across the board.

7295DA3F-74B8-4C78-817D-C7B1FCB3BCEE.jpeg

All +P+ means is that you are over +P, that can be by one unit of measure all the way to kaboom.

The actual pressures are going to be barrel/condition dependent and they recognize this.
40C7FE63-01A3-47A8-8DBE-A8BFF7DC3585.jpeg

They do not do stuff like trapdoor vs marlin vs Ruger #1 45-70 loads though.


F0B898AB-6DD3-4AA6-B720-3DD8BAF567AF.jpeg

This link should be more than you want to know :)

https://saami.org/wp-content/upload...99.4-CFR-Approved-2015-12-14-Posting-Copy.pdf
 
SAAMI has a list of cartridges and the maximum pressures recommended. The question is, are those pressures firearm dependent?
While the short answer is that all new guns made or imported to the USA need to meet SAAMI specs, and are tested to X times that pressure as a safety cushion, the real answer is the pressures ARE firearm dependent.

The problem is TIME.

There are thousands of guns in use today, made before SAAMI specs applied. In the case of "grandpa's old 38" made in 1895.... This was not only made before SAAMI specs, but also before modern steel alloys were introduced. It may do fine with 38 target loads, but you dare not try any modern 38 SD loads, or even +P loads in it. That gun will have completely different pressure allowances than "dad's old 38" made in 1952.

This may be far from what you intended, but users need to be very careful with "blanket statements" that cover ALL guns made in ANY year.

Just my 2 cents.
 
Probably nothing I'll put down here will be new to you.

So, if you look at the screen clips that jmorris gave you above, note the page number at the top left corner 203 of 375. Starting just about at 203 and going to the end is excruciating detail of all the equipment SAAMI uses in their tests including the exact proofing chamber cuts for each cartridge, the location of strain gauges used, bore sizes for the pressure vents, and standards for the copper disc used in the testing, ad Infinium. In no way does this test equipment even remotely resemble a gun barrel other than in the general chamber cut and the test cartridges and proof loads.

All pressure data is "internal ballistics" and is what all signatory manufacturers use for their design criteria, i.e. the gun and ammo you buy. CIP is the European equivalent for SAAMI. Duh right? Nothing new.

rjwobbly makes good points with time and the development of steel quality. Krupp was the best, but now we have modern stainless. Will Krupp stand what modern stainless will? I don't think so.

Maybe we should rephrase your original question from "is the data firearm dependant" to one that's more like "firearms are SAAMI/CIP data dependant" which might be a closer match. Like all standards such as, for instance, the minimum breaking strength of a car seatbelt, SAAMI/CIP builds in safety factors to protect both the manufacturer and the user. If we, as users, blow up a firearm, we've really exceeded the design standard including all of the safety factors.

No, I'm not going to tell you that you'll kill yourself. One only has to look at Minor and Major power factors to see that we shooters regularly exceed pressure standards. In a precision long-range rifle, limits get pushed all the time. But, it's done with some criteria and knowledge.

Ordinary shooters are limited in the data that we can determine, and that's the real problem, isn't it? Testing equipment and predictive software are expensive.

Just where have we pushed a little too far, and what and when will the consequences show up? Hell, I'm hesitant to buy used firearms for that reason.
 
One thing that may intrest you and be relivent is the steel action strain cycle data. The standard assessment is that if used inside of Sami specs that strain cycle is well below any real working of the barrel or action for stress/strain cycles. That is a saftey factor as listed above. As you go higher in pressure that stress/strain curve changes sharply to failure in only a few cycles. A single event can cause a sever reduction in strength with no outward indication or way to see there is a problem. If your intrested I can try and hunt down the graph
 
They are cartridge dependent. +P isn’t a given pressure just an indicator that the ammunition is over pressure for the cartridge. It’s not even a consistent amount/percentage over their standard across the board.
So if I rebarrel a Mauser '98 action and chamber the correct diameter barrel for .38 Special, the rifle will suffer damage (to include extreme wear) from over pressure? I would not have thought so.


The actual pressures are going to be barrel/condition dependent and they recognize this.
You realize you just contradicted yourself.

They do not do stuff like trapdoor vs marlin vs Ruger #1 45-70 loads though.
Which is my reason for asking the question.

In fact, it does not address the question at all. Certainly worthwhile reading on the subject, but not really responsive.
 
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While the short answer is that all new guns made or imported to the USA need to meet SAAMI specs, and are tested to X times that pressure as a safety cushion, the real answer is the pressures ARE firearm dependent...

...There are thousands of guns in use today, made before SAAMI specs applied. In the case of "grandpa's old 38" made in 1895...

This may be far from what you intended, but users need to be very careful with "blanket statements" that cover ALL guns made in ANY year.

Just my 2 cents.
Thanks. At least you recognize you are not addressing the actual question. I do understand what you are saying but the rifle I have is a modern steel made mechanism. Rifle built in the last few years. (I really don't know the time lapse from 'finished product' at the factory in Czech Republic to 'on the wall' in the gun store in Nebraska, but I'm sure it is less than a decade.)

I think I will cautiously work on a load for the 7.62x39mm Soviet round with a 150 grain bullet. Tula factory makes one with the 154 grain (probably 10 grams) 7.62x54mmR bullet. Strikes me as equivalent to a bottom end .30-30 round.
 
One thing that may intrest you and be relivent is the steel action strain cycle data. The standard assessment is that if used inside of Sami specs that strain cycle is well below any real working of the barrel or action for stress/strain cycles. That is a saftey factor as listed above. As you go higher in pressure that stress/strain curve changes sharply to failure in only a few cycles. A single event can cause a sever reduction in strength with no outward indication or way to see there is a problem. If your intrested I can try and hunt down the graph
As several others, you give factual inform without any relationship to the question I pose.
I do understand that with even over stressing steel a little, the effect is cumulative. (Like beating on a steel rod with a big hammer.) However, is the pressure and related strain cycle set by the firearm or the cartridge?

The CZ 527 rifle I'm using is also chambered for .223 Remington or 5.56x45mm NATO. The maximum pressure level for 5.56x45mm (according to SAAMI) is 74,500 somethings or other. Copper units of pressure, how I make it out. SAAMI does not list or comment on pressure for 7.62x39mm. Wikipedia (sometimes not well regarded) shows the .223 Remington cartridge as 55,000 psi (SAAMI) and 62,366 psi (CIP). From the same source the 7.62x39mm round as 45,010 psi (SAAMI) and 51,490 psi) CIP. Therefore, the rifle can reasonably handle the strain cycle of either. With some 'room' for the 7.62 Soviet round.

So, we're back to the question: Which limit does one observe? I understand some (typically old) cases won't handle much more than the original loading. This does not seem to be applicable, as cases are 'new'.

Would you suggest the strain cycle is altered by using a larger caliber or heavier bullet?
 
Probably nothing I'll put down here will be new to you.
You actually made some sense and seemed to understand my question.
NMexJim said:
Maybe we should rephrase your original question from "is the data firearm dependant" to one that's more like "firearms are SAAMI/CIP data dependant" which might be a closer match.
From a manufacturing stand point, you are likely correct. But SAAMI does not have maximum pressure levels for any sort of firearm action. For instance, there is no listing saying "Remington 700 action will accept pressures of XX, xxx psi." Only the psi values for cartridges.

The rather common act of 'rebarreling" a rifle seems to have answered my question. One would not thinkingly rebarrel a 1892 Mauser to .30-06 Springfield and think the rifle is now suitable for full charge loads. Well, I wouldn't.
 
So, we're back to the question: Which limit does one observe? I understand some (typically old) cases won't handle much more than the original loading.

SAAMI and CIP use slightly different methods to measure pressure.

https://en.wikipedia.org/wiki/Small_arms_ammunition_pressure_testing


The CZ 527 rifle I'm using is also chambered for .223 Remington or 5.56x45mm NATO. The maximum pressure level for 5.56x45mm (according to SAAMI) is 74,500 somethings or other. Copper units of pressure, how I make it out.

Where are you getting 5.56x45mm SAAMI specs? They don't list it in their manual that I can see, unless I'm missing something. Thanks.
 
Yes; SAAMI and CIP use different methods and have different criteria. CIP pressure levels are normally higher, it seems.

You are right. I used the .223 Remington scores instead. I should have changed the wording in my post.
 
So if I rebarrel a Mauser '98 action and chamber the correct diameter barrel for .38 Special, the rifle will suffer damage (to include extreme wear) from over pressure? I would not have thought so.

What would have given you that impression?

The original caliber that action was chambered for is more than strong enough for 38 special. So you could chamber one in 38 and load above their maximum pressure for 38 spl but that’s not going to make them change their standard.

41B77B62-DE85-4A61-9E45-D5C593A573A8.jpeg

^ that also points out the disparity between the methods they use to pick a “maximum”

https://firearmshistory.blogspot.com/2011/01/testing-firearms-measuring-chamber.html

You realize you just contradicted yourself.

Didn’t intend to, SAAMI sets a standard for a round that ammunition is manufactured to by using their test barrels, what you get from that ammunition, pressure and velocity wise will likely be different depending on what you fire it from.

Might be easiest to see if we take it to an extreme. Say 264 win mag. They pick a max of 64,000 psi. If you take that round and fire it from a 300 win mag, you will have greatly reduced average pressure (along with a blown out case and extremely poor accuracy). So it’s obvious what barrel a round is fired through is going to have an effect but that doesn’t change their standard.

“They do not do stuff like trapdoor vs marlin vs Ruger #1 45-70 loads though.”

Which is my reason for asking the question.

This one?

SAAMI has a list of cartridges and the maximum pressures recommended.

The question is, are those pressures firearm dependent?

The SAAMI Maximum pressures are not a pressure your likely going to get, it’s a standard. Being above that standard doesn’t automatically mean your going to blow up a firearm so chambered either. SAAMI sets a standard for a cartridge based on input from the list of folks at the front of the link I posted above and others. Down the line you chamber a firearm that can hold greater pressures than the original and they are not going to increase their standard for that cartridge, even if you can safely load the round over their set maximum.

So the 45-70 came out 53 years before SAAMI was founded, in 1926. So the standard they set was for the firearms it was used in. Fast forward another 46 years to 1972 and the Marlin 1895 that could handle another level of pressure. If SAAMI reset their standard to match it, it wouldn’t be safe in the old stuff. Keep it the same and ammunition is backwards compatible.

If you don’t like it, you make a change so your new ammunition can’t be put in the old stuff but is otherwise the same and change the name from 45-70 to 450 Marlin and they will set the new standard. That doesn’t mean you can’t load 45-70 for a Marlin well over the SAAMI max for the cartridge but that doesn’t change their standard.
 
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What would have given you that impression?
Your statement.

jmorris said:
Might be easiest to see if we take it to an extreme. Say 264 win mag. They pick a max of 64,000 psi. If you take that round and fire it from a 300 win mag, you will have greatly reduced average pressure (along with a blown out case and extremely poor accuracy). So it’s obvious what barrel a round is fired through is going to have an effect but that doesn’t change their standard.
You're going to pretend intentionally shooting the wrong cartridge is what I'm curious regarding? No wonder.

jmorris said:
So the 45-70 came out 53 years before SAAMI was founded, in 1926. So the standard they set was for the firearms it was used in. Fast forward another 46 years to 1972 and the Marlin 1895 that could handle another level of pressure. If SAAMI reset their standard to match it, it wouldn’t be safe in the old stuff. Keep it the same and ammunition is backwards compatible.
Then the loading manuals printing different load data for 'trapdoor', and two other levels of pressure in manuals are all unethical?

jmorris said:
If you don’t like it, you make a change so your new ammunition can’t be put in the old stuff but is otherwise the same and change the name from 45-70 to 450 Marlin and they will set the new standard. That doesn’t mean you can’t load 45-70 for a Marlin well over the SAAMI max for the cartridge but that doesn’t change their standard.
Just exactly what was done to .45-70 Springfield and .257 Roberts.

I pretty much have the answer. More gibberish is not needed.
 
What would have given you that impression?

The original caliber that action was chambered for is more than strong enough for 38 special. So you could chamber one in 38 and load above their maximum pressure for 38 spl but that’s not going to make them change their standard.

View attachment 972903

^ that also points out the disparity between the methods they use to pick a “maximum”

https://firearmshistory.blogspot.com/2011/01/testing-firearms-measuring-chamber.html



Didn’t intend to, SAAMI sets a standard for a round that ammunition is manufactured to by using their test barrels, what you get from that ammunition, pressure and velocity wise will likely be different depending on what you fire it from.

Might be easiest to see if we take it to an extreme. Say 264 win mag. They pick a max of 64,000 psi. If you take that round and fire it from a 300 win mag, you will have greatly reduced average pressure (along with a blown out case and extremely poor accuracy). So it’s obvious what barrel a round is fired through is going to have an effect but that doesn’t change their standard.



This one?



The SAAMI Maximum pressures are not a pressure your likely going to get, it’s a standard. Being above that standard doesn’t automatically mean your going to blow up a firearm so chambered either. SAAMI sets a standard for a cartridge based on input from the list of folks at the front of the link I posted above and others. Down the line you chamber a firearm that can hold greater pressures than the original and they are not going to increase their standard for that cartridge, even if you can safely load the round over their set maximum.

So the 45-70 came out 53 years before SAAMI was founded, in 1926. So the standard they set was for the firearms it was used in. Fast forward another 46 years to 1972 and the Marlin 1895 that could handle another level of pressure. If SAAMI reset their standard to match it, it wouldn’t be safe in the old stuff. Keep it the same and ammunition is backwards compatible.

If you don’t like it, you make a change so your new ammunition can’t be put in the old stuff but is otherwise the same and change the name from 45-70 to 450 Marlin and they will set the new standard. That doesn’t mean you can’t load 45-70 for a Marlin well over the SAAMI max for the cartridge but that doesn’t change their standard.
no sense in throwing more good info at this. archie knew the answer to the question before the thread was started. part of being helpful is getting stomped on by those you are trying to help.

luck,

murf

murf
 
Then the loading manuals printing different load data for 'trapdoor', and two other levels of pressure in manuals are all unethical?

Not sure how ethics get involved, it is their standard, their rules made by them.

You could found your own organization and set your own standards. Load 45-70 to 1,3.8 or 150,000, units of Archie, whatever you arbitrarily decide. If others trust your standards, they will follow.
 
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