I've seen IIRC 45k psi loads for the Marlin. Anyone know what the recommended max is in CUP?

The literature supports a safe operating pressure for the Marlin 1895 45-70 of 40,000 CUP.

And Paco Kelly can tell you that the Marlin will let go before the Model 94.

First, one would think an idiot would take the Marlin 1895 to 86,000 PSI and then brag about it.

Second, PSI and CUP are the results of two different measuring systems and are not equivalent. 40,000 CUP is probably around 43,000 PSI (calculated value is 42,732.4 PSI R2=.927). The 450 Marlin chambered in essentially the same Marlin rifle as the 45-70 has a pressure spec of 43,500 PSI.

Third, where does Conley Precision Cartridge document their 45-70 loads for the Marlin 1895 at 42,000-43,000 PSI? From the velocities listed it doesn't look like they are loaded to that level.

Finally, the questioner asked about the pressure limits for the Marlin 1895 in CUP not PSI. Hence, the safe operating pressure of the Marlin 1895 45-70 is 40,000 CUP.

Well, what would one call someone who takes the Marlin 1895 to 86,000 PSI, let alone two. What possible purpose would it serve, why would a person do such a thing? If it was testing to determine destruction limits perhaps it would be a good idea to preface such remarks as such for the benefit of those who might otherwise think such a practice was idiotic.

And what would one call someone who calls others idiots based on very little information?
I didn't hear him bragging.
I don't know why he did it.
Don't be a poopy-head.
And thanks for clarifying the question. I have seen 43kpsi as a working max, it's just that the action wasn't around when everyone used CUP, so I'm wondering what to tell Powley.
I would guess it's around 40k, but thought maybe someone hadit somewhere....

quote:

So . i supose 40.000 would be a good place to hold up if your first time reloader.

Another idiotic statement. Makes no differentiation between PSI and CUP. Implies that just because someone is not a first time reloader that it is OK to exceed safe pressures. Call me a poopy-head all you want but this kind of information presented by Mr. Martin Potts is not helpful or prudent.

Just a question. When was "everyone" using CUP? Certainly the copper crushers were being used in 1972 when the modern Marlin 1895 was introduced. Before about the 1960's the only measurement system there was for
chamber pressure was the copper crusher method. All of the literature in the early history of the modern Marlin 1895 in fact used CUP in describing the limits of the rifle.

40,000 CUP is roughly equivalent to 43,000 PSI if this helps.

I did away with my own post's .Becouse of saftly reasons.

Your right Jackfish there is a diffrents but .. PSI and the use of it dates back much father then 1960. and thats the messurement system
used by many of us.


Martin

PA Bullet's

Well great then. It should be easy to find a CUP max. I figured my books reached back pretty far, but I can only find psi for the 1895.
Anyone have the number? Just for shits and giggles, since it sounds like I can use the 40k number for estimates.

The Lyman reloading manual is one of the most respected sources available. It’s clearly written, a pleasure to read, and it sheds some interesting light on the history of terminology in the measurement of chamber pressure. Before about the 1960's the only measurement system we had for chamber pressure was the copper crusher method. Up until that time, what we now call CUP was commonly known by two different names: CUP and PSI. The two were used practically interchangeably. Of course, this use of PSI was incorrect. It wasn't much of a problem until piezoelectric and strain gauge systems became commonly available. These systems, of course really do measure in PSI. When they arrived on the scene, it caused a lot of concern and confusion. “For years, 52,000 PSI (crusher method with erroneous designation) had been published as maximum for the 270 Win. Suddenly, there were new publications showing 65,000 PSI …as maximum.†Lyman 47th Reloading Handbook, p92

If you look at any publications before about 1965, and they say that PSI and CUP are not the same, and that you should not attempt to convert one to the other, they are talking about the old, incorrect use of the term PSI, not the modern, correct use of PSI from strain gauges and piezoelectric pressure meters.

So, perhaps the greatest area of misunderstanding of pressure terminology, has arisen from earlier practice of referring to chamber pressure as some number of "pounds per square inch (psi)". Many earlier ballisticians believed that results of a firearm chamber pressure tests were accurately described as psi. The truth was their test results had little to do with actual pounds per square inch.

Their "crusher" testing and the testing still used in many ballistic labs, uses a barrel with a hole drilled into the chamber perpendicular to the bore's axis, usually 1" from the rear edge of the chamber. A slip fit piston is fitted into this hole with its end contoured to precisely fit the inside of the barrel chamber. In testing, a cartridge is loaded into the chamber and the piston slipped into place. A copper crusher is then stood on top of the piston and is securely held in position with an anvil. When fired, the cartridge case has a small disc rupture from it at the location of the piston hole. The hot and rapidly expanding gasses in the chamber push equally on the bullet base and on the piston base. The piston in turn moves heavily on the copper crusher, which is forced to collapse to a varying degrees depending on the total amount of pressure applied to it by the piston.

The amount of "crush" of the copper cylinder is then measured carefully and this crush length is compared to a tarage table which lists a specific value for the amount of crush which occurs.

There is, of course, more to the crusher pressure testing system then the foregoing few words might suggest. The point to be made is that the copper (lead for shotguns and some handguns) crusher method is a valid and useful tool for ammunition evaluation, but it does not actually express pressures in true pounds per square inch. This did not escape the attention of newer generation ballisticians. They set out to correct the misnomer of pounds per square inch and used instead the designation copper units of pressure (CUP's) or lead units of pressure (LUP's). However, the erroneous term PSI had become so accepted that it was frequently used interchangeably with CUP or LUP. While such use was technically wrong it created no major problems when everyone was talking about the same thing; the result of a copper or lead crusher pressure test.

Sources: Denton Bramwell and The Reload Bench

Who do you believe?

Hodgdon #27: All Marlin 1895 45-70 loads limited to 40,000 CUP.

Hornady #4: Marlin 1895 45-70 loads are limited to 40,000 CUP.

Barnes #1: The Marlin 1895 chambered in 45-70 is intended to be used with loads up to 40,000 CUP.

Mic McPherson 1994 Handloader's Digest: "The 1895 is built with the same tough steel as the 444 Marlin, which is based on the same action. Maximum pressure specification for the 444 Marlin is 44,000 CUP. Since the 45-70 case has about 10 percent greater cross sectional area than the 444, 45-70 loads at about 40,000 CUP should generate approximately the same bolt thrust as maximum loads in the 444."

Joe D'Alessandro, RealGuns.com: "The Marlin can handle 40,000 c.u.p., not much less than the 50,000 c.u.p. limit for this cartridge for the super duty Ruger No.1 action."

OK, now swallow hard.

Catapultam habeo. Nisi pecuniam omnem mihi dabis, ad caput tuum saxum immane mittam.

Jackfish, although I appreciate the succinctness with which you explain the copper crush method, it's something I think most of us understand already. As to who I believe, it seems they all are saying the same thing, i.e., 40k CUP. That seems to "read" right with Powley. Now where the "swallow hard" part comes in, is totally lost on me.
Thanks everyone.

Check this out:
Lyman sets up a universal receiver with both copper crush and piezo measurement. Fires a bunch of 10rnd 30-06 in it.
The factory, control load had an average psi of 54.1k, and average CUP of 46.4 (10k EV for both!!!)
Jacketed bullet, fast powder, the numbers were 49.7k and 42.5k.
Jacketed bullet, intermediate powder: 58.1k and 46.6k.
Jacketed bullet, slow powder: 52.3k and 42.9k.
That all looks kinda like I'd expect. Now things get weird.
Lead bullet, fast powder: 37k, 40.4k
Lead bullet, intermediate powder: 25.9k, 29.3k
Lead bullet, slow powder: 18.1k and 15.4k
Unless there's some SERIOUS typos happening, CUP is more than psi for the lead bullets with fast and intermediate powders, at least for the '06 in that UR on that day.
Strangely, the variations are all about 1.15:1 on one side or the other, i.e., the flipflopped numbers for the first two sets of lead loads would fit in with everything else.
Could they have put those numbers in the wrong column?
If so, then we can stick with the idea of 45k psi = 40k CUP.

quote:

Jackfish, although I appreciate the succinctness with which you explain the copper crush method, it's something I think most of us understand already.

This was a response to Martin Potts regarding the use of CUP vs. PSI to demonstrate he might be afflicted with adhering to the discrepancy described.

quote:

but .. PSI and the use of it dates back much father then 1960. and thats the messurement system used by many of us.

quote:

If so, then we can stick with the idea of 45k psi = 40k CUP.

You could if you wanted to, but that wouldn't make it right. As has already been stated twice, in the Marlin 1895 45-70 40,000 CUP is about 43,000 PSI. The SAAMI spec for the Marlin 1895 450 Marlin is 43,500 PSI and the 450 Marlin has a slightly smaller cross sectional area interfacing the bolt face than the 45-70. Who were your sources promoting 45,000 PSI in the Marlin 1895 45-70?

The "swallow hard" comes from you not seeming to accept what some people present.

Catapultam habeo. Nisi pecuniam omnem mihi dabis, ad caput tuum saxum immane mittam.

Dude, you've lost me completely. Not at all sure where you're coming from, but it doesn't sound friendly.
As evidenced by the Lyman tests, you really can't equate psi to CUP. Even the same bullet measured different variances, i.e., there might be a 3k units difference in one shot, and another shot of the same load might measure 1k difference. There seemed to be no real conversion factor available.
Anyway, I'm allowing that 40k seems right, and you say I'm not accepting what's presented.
Way more than I bargained for starting this post. Looking for a number in CUP to tell Powley for some made-up wildcats. For now, I'll go with 40k, since it seems to be reasonable.
Cheers to all, and goodnight.

I guess you could say I'm as lost as you, but I'm not. As to being friendly, you blew that by ignoring credible responses to your question.

Your question was answered with the first response.

Then you said:

quote:

I would guess it's around 40k, but thought maybe someone hadit somewhere....

Yeah they did. But you still didn't believe it:

quote:

Anyone have the number? Just for shits and giggles, since it sounds like I can use the 40k number for estimates.

Estimates? No, that is the value in CUP for the safe operating pressure of the Marlin 1895 45-70. You obviously were still incredulous, so I took four minutes to lookup and provide five sources. Then you said:

quote:

it seems they all are saying the same thing

No, it doesn't "seem" they all are saying the same thing, they are all saying the same thing.

Then when provided twice with the safe operating pressure for the Marlin 1895 45-70 in both CUP and PSI you erroneously hypothosize:

quote:

If so, then we can stick with the idea of 45k psi = 40k CUP.

quote:

Anyway, I'm allowing that 40k seems right

No, it is right.

And then finally you still are not sure:

quote:

For now, I'll go with 40k, since it seems to be reasonable.

What do you think it is going to change after 25 years of the literature saying the safe operating pressure of the Marlin 1895 45-70 is 40,000 CUP?

Goodnight indeed.

One must always remember to look for pressure signs so that when one see them they are already over the safe maximum for the Marlin.

Me_Plat, and just what pressure signs are you going to see in the Marlin 1895 45-70 that will indicate one is over the safe maximum? The classic signs of excessive pressure (primer and primer pocket condition, sticky extraction, extractor marks, etc.) are unlikely to show up in the Marlin 1895 45-70 until one is quite a bit over its safe operating pressure. Not very comforting. I think you should really care.

Jakfish, somhow I missed your first post, or else I would've just asked you to clarify.
Now your attitude makes a little more sense.
It's been a pleasure.

Sorry for the misunderstanding. Thanks. Good luck with your experiment.

Are any of you able to tell me the maximum working pressures for the Win. 71 or the '86?
Thanks,
FRank

Frank, the literature suggests the safe operating pressure of the modern Winchester 1886 in the 45-70 Gov't is 50,000 CUP. The Winchester M71 is essentially the same action as the 1886. However, any cartridge based on the 348 Winchester necessarily has a larger cross sectional area interfacing the bolt than the 45-70. Hence, the safe operating pressure of those cartridges in a Winchester 1886 or 71 would probably be around 45,000 CUP or around 50,000 PSI.