pressure -- marlin 444 vs marlin 45-if 70

[mkl]

I read somewhere that the Marlin 1895 rifles in 444 Marlin and 45-70 are basically the same action. The writers argument was that the 444 action is rated at 44,000 cup that the 45-70 should be safe at the same pressure level. This would imply that the tier 3 loads (ruger #1, etc.) would be safe in the Marlin 1895 in 45-70 caliber.

Any comments as to the validity of this assertion?

I don't plan on trying the above, but was just curious if anyone has any actual test data to confirm or deny the 444Marlin = 45-70Marlin in the 1895 actions as far ae pressure levels are concerned.

Edit: I don't know how the "if"got in the title; just ignore it.

 

[mcb]

I suspect you probably could push closer to 444 Marlin but I will throw out the following thought to consider.

Assuming both barrels have the same outside diameter, which I believe is true, and for my math I assumed that the OD is ~.800 (happy to redo the math with a more accurate measurement).
-The 444 Marlin has a minimum chamber diameter at the base of the cartridge of .470 inch.
-The 45/70 has a minimum chamber diameter at the base of the cartridge of .507 inch.

If we load both cartridges to the same peak pressure the larger diameter chamber of the 45/70 will increase the stress on the gun. The hoop stress in the barrel at the chamber will go up by ~28%. The thrust on the bolt goes up by ~16%. The margin of safety would probably tolerate that but it would likely lead to increase wear on the action, maybe. If you're dead set on trying this work your loads up slowly an ask your self do you really need that moderate increase in velocity/energy?

 

[Slamfire]

Assuming both barrels have the same outside diameter, which I believe is true, and for my math I assumed that the OD is ~.800 (happy to redo the math with a more accurate measurement).
-The 444 Marlin has a minimum chamber diameter at the base of the cartridge of .470 inch.
-The 45/70 has a minimum chamber diameter at the base of the cartridge of .507 inch.

If we load both cartridges to the same peak pressure the larger diameter chamber of the 45/70 will increase the stress on the gun. The hoop stress in the barrel at the chamber will go up by ~28%. The thrust on the bolt goes up by ~16%. The margin of safety would probably tolerate that but it would likely lead to increase wear on the action, maybe. If you're dead set on trying this work your loads up slowly an ask your self do you really need that moderate increase in velocity/energy

Outstanding analysis!

 

[Enfielder]

Outstanding analysis!

As opposed to the usual backwater approach of running it a bit hot and backing it off when the case splits or the bolt enters your forehead.

 

[Slamfire]

As opposed to the usual backwater approach of running it a bit hot and backing it off when the case splits or the bolt enters your forehead.

So we don't get a good blowup picture. Bummer

 

[earlthegoat2]

There is plenty of load data out there that shows lever action 45-70 only being loaded to 27-37k CUP with a very few 40k CUP outliers.

The same data sources show 444 Marlin typically being loaded to maxes of 40-44k CUP.

This should give an idea that the load data providers don’t think it is a good idea to push the 1895 action in 45-70 up to 444 Marlin pressures.

 

[Ranger99]

Never considered any pressure issues.
I load for accuracy with my 444 Marlins
and never take pressure or velocity into
account. I'm going by published data so
I'm assuming all is well. The deer and
varmints I've killed never gave me any
backtalk concerning what was flung
their way, so I remain blissfully ignorant

 

[3Crows]

F=PxA. The area of the .45-70 cartridge upon the bolt is larger as is the bore and bullet base than that of the .444 Marlin. Calculate the Force for both .444 and .45-70 at their maximum operating pressures, there is simply more "horsepower" in the .45-70 even at a lower working pressure. The .45-70 does not need to be pushed that hard to equal the .444 for muzzle energy but the accepted and oft argued limit is 40,000 CUP for the Marlin 1895 in .45-70 and that must kick like a _________!

There is another consideration, the barrel threading into the receiver to allow the magazine tube is relatively thin for the .45-70 to clear the cartridge rim. I do not know if Marlin carried the truncated threads over to the .45-70 after doing such with the.450 or if truncated threads were found not needed and dropped from both. I do not know what Ruger is doing in this regard either for this critical area. The .444 Marlin would have more thickness there. Essentially the .444 Marlin needs that higher pressure to accomplish it's design goals and the .45-70 does not because they are not intended really to occupy the same niche. That the .45-70 killed of both the .444 and the .450 is sort of a shame, but then, .45-70 Government is always the right answer to any question .

 

[earlthegoat2]

There is another consideration, the barrel threading into the receiver to allow the magazine tube is relatively thin for the .45-70 to clear the cartridge rim. I do not know if Marlin carried the truncated threads...

Is this where the minor diameter of the barrel threads is increased and the major diameter is left the same so as to thicken the barrel metal around the breech?

I see this done on hot rod 1895 custom builds from time to time.

 

[Enfielder]

So we don't get a good blowup picture. Bummer

View attachment 1119083


View attachment 1119084

Entertainment at its best!!

 

[3Crows]

Is this where the minor diameter of the barrel threads is increased and the major diameter is left the same so as to thicken the barrel metal around the breech?

I see this done on hot rod 1895 custom builds from time to time.

Yes sir, you have it. Thread truncation is basically taking the top of the thread off on the barrel and the same on the receiving female thread in the receiver which reduces the amount of material needed to accept the male thread and also removes the V in the (OD) of the female thread thus eliminating to a large degree a stress riser from which a crack might propagate. Rolling threads can accomplish a similar result. This is not my area of engineering expertise and am not trying to pass myself off as such. In propeller design once upon a time there were threaded propeller blades which were threaded into a collet for retention in the hub. These threads were critical and during subsequent overhauls it was found that the threads were often scratched or damaged leading to blade failure and thus catastrophic propeller failure which is really bad for all involved. The threads were truncated on subsequent product to eliminate the possible stress riser.

 

[mkl]

Thanks all for the replies. As I said in my original post, I have no intention of trying to push my 1895 to tier 3 pressure levels; mid-level tier 2 is about the maximum recoil my 78 year old shoulder will tolerate.

For any who may want to try pushing the Marlin 1895 to Ruger pressure levels, I refer you to the picture in post #5.

 

[3Crows]

Slight change of subject but pertinent, I have read, understanding that in general CUP is not the same as PSI but I have read that some calibers, and in this case. 45-70, that we can consider the two interchangeable?

I had surgery on my shoulder to reattach the bicep tendon after a car wreck in which a cell phone texting woman ran through a double stop sign. I am still a little sore there now a year latter. After going to the range Friday last and going through about 40 or 50 rounds of Trail Boss at 13.0 and some H4198 at 30 to 32 grains and some HMS Cowboy, all with 405 grain HCL bullets, my shoulder has a bruise on it. Of course that is from shooting off a bench on bags. I could not wish to endure the recoil a 400 plus grain bullets might deliver ahead of 44,000 psi/cup!

The blown up rifle in the photos provided, thank you, to my eye that appears to be some sort of obstruction as at least a contribution or a seriously overloaded (double charged at max) cartridge? I say this due to the banana peel like splits so far up the barrel. I hope whoever did that is okay .

 

[Jim Watson]

So is the action the same for .444, .45-70, and .450 Marlin?
The .450 Marlin was apparently introduced to provide a factory load comparable to the popular but not officially sanctioned "modern .45-70." Its SAAMI maximum is 43500 ppsi vs 42000 ppsi for .444. A Hodgdon top load for .45-70 "lever action" is 37500.

Back in the 1970s Jac Weller wrote of plant tours. He said that Marlin was sending barrels for the then-new .444 out to Remington for heat treating to handle its higher pressure since they did not have the equipment.

 

[GeoDudeFlorida]

Slight change of subject but pertinent, I have read, understanding that in general CUP is not the same as PSI but I have read that some calibers, and in this case. 45-70, that we can consider the two interchangeable?

EDIT: Nah. Not really.

 

[Jim Watson]

But by chance, the SAAMI maximum pressure for .45-70 IS the same number in both systems.

I think there is way too much time spent mansplaining the difference in crusher and pizeo pressure readings.
How many of us here have either type of gauge? We are dependent on the literature. What boots it that .30-06 maxima are 50000 CUP and 60000 ppsi? We are not measuring it, we are looking at the powder charge said to give the maximum, either way.

 

[GeoDudeFlorida]

But by chance, the SAAMI maximum pressure for .45-70 IS the same number in both systems.

I think there is way too much time spent mansplaining the difference in crusher and pizeo pressure readings.
How many of us here have either type of gauge? We are dependent on the literature. What boots it that .30-06 maxima are 50000 CUP and 60000 ppsi? We are not measuring it, we are looking at the powder charge said to give the maximum, either way.

"Mansplaining"? LOL!! Okay. Well, I'm fine letting it go with, "Nah," from now on and ignoring the questions entirely. I'm not here to explain anything or give an opinion, after all. But that won't stop the Science Guys from perpetuating the myth that CUP and PSI are interchangeable in some circumstances. I know better and have never had a problem so I'll let the REAL experts give a nod and passively agree. What harm could there possibly be?