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Thread: Pressure?

  1. #1

    Question Pressure?

    Question is this: I recently purchased a Win 71, 348 cal and it's recommended loads are around the 35,000 to 36,500 psi. Those pressures seem to be standard for that lever gun. I read where folks have rechambers the 71 to more intense rounds such as the 450 Alaskan, 450 Ackley and other larger rounds. Now it seems to me that these more powerful rounds will have greater pressures...but still utilize the same lever action. Does this mean the 71 action can safely withstand a lot more pressure than the recommended loadings of the 348?
    If you like getting kicked by a mule...then you'll "love" shooting my .458.

  2. #2

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    Quote Originally Posted by Maydog View Post
    Question is this: I recently purchased a Win 71, 348 cal and it's recommended loads are around the 35,000 to 36,500 psi. Those pressures seem to be standard for that lever gun. I read where folks have rechambers the 71 to more intense rounds such as the 450 Alaskan, 450 Ackley and other larger rounds. Now it seems to me that these more powerful rounds will have greater pressures...but still utilize the same lever action. Does this mean the 71 action can safely withstand a lot more pressure than the recommended loadings of the 348?
    Not a clue, but I can say that the loads I use in my 450 are rated in the 35k range. And they're PLENTY, so I'm not quite sure why you'd need to press higher than that in the original 348. If I was going to dink around with higher pressures I'd sure use one of the recent manufacture models rather than an original, just out of respect for the original.

    The only original 348 I know of still in regular use was purchased new by the current owner and digested nothing but factory loads in the 50 years or so since. There's very little bluing left on that old veteran and it's taken quite a few brown bears and no end of deer. The action is still tight as a drum.

  3. #3

    Talking

    Quote Originally Posted by BrownBear View Post
    Not a clue, but I can say that the loads I use in my 450 are rated in the 35k range. And they're PLENTY, so I'm not quite sure why you'd need to press higher than that in the original 348. If I was going to dink around with higher pressures I'd sure use one of the recent manufacture models rather than an original, just out of respect for the original.

    The only original 348 I know of still in regular use was purchased new by the current owner and digested nothing but factory loads in the 50 years or so since. There's very little bluing left on that old veteran and it's taken quite a few brown bears and no end of deer. The action is still tight as a drum.
    Hi Brown: I'm not interested in higher pressure...just a curiosity. I have real nice rifle that I intend to hunt with, and it will do all I want it to. It must be quite strong though if it can stand those higher pressures. Just because it's an older cartridge, doesn't make it any less effective and I can't wait to hunt with it...and I do respect it, like you said. Thanks.
    If you like getting kicked by a mule...then you'll "love" shooting my .458.

  4. #4

    Default

    Quote Originally Posted by Maydog View Post
    Hi Brown: I'm not interested in higher pressure...just a curiosity. I have real nice rifle that I intend to hunt with, and it will do all I want it to. It must be quite strong though if it can stand those higher pressures. Just because it's an older cartridge, doesn't make it any less effective and I can't wait to hunt with it...and I do respect it, like you said. Thanks.
    I suspect the lack of bonified efforts to increase pressures is simply a question of timing. The 348/71 blossomed and faded long before any of the factories ventured into +P or +P+ loadings. There just wasn't the market incentive to add it to the list of candidates. Same applies for the newer high performance powders floating around.

    If the combo had been more readily available like the various Marlin 45-70s as the craze hit, I think you'd see similar efforts and probably a lot higher regard for the 348. I've seen loads for the 348 and 450 that obviously push up the pressures, but I put as much faith in them as politicians. I will say that if I was inclined to push pressures with guns, I'd be a lot more comfortable doing it with the 71 than with the Marlin, even recognizing that I really like the Marlin.

  5. #5
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    Default

    Came across this article and thought you might be interested. Now I want one too.

    http://www.leverguns.com/articles/taylor/model71.htm

  6. #6
    Member pinehavensredrocket's Avatar
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    Default

    the model 71 (sister to the 1886) is a very strong action that will handle pressure at a level higher than the .348 cartridge is designed to contain. this sharply tapered bottleneck case is inefficient and develops bolt thrust that is undesireable and much greater than it should be.

    it is the cartridge that limits your rifle's pressure ceiling, and in the stock form should not be over loaded. the ackley improved chamber removes alot of the body taper and will therefor handle more pressure. follow your load manual on this one, unless you decide to rechamber to a different round.

    happy trails.
    jh

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    Default Sounds good but...

    The force on the bolt face follows the simple F = P x A ( force = area x pressure) formula. While a tapered case may bind up in the action at a lower pressures the case doesn't have enough strength to carry any significant load by gripping the case walls tighter. Figure out the area of the case wall and the tensile strength of catridge brass and you can see why this is true.

    You can rebarrel to a case with a smaller head and load to higher pressures but re-chambering won't help the bolt thrust from pressure in the .348 parent case.


    Quote Originally Posted by pinehavensredrocket View Post
    the model 71 (sister to the 1886) is a very strong action that will handle pressure at a level higher than the .348 cartridge is designed to contain. this sharply tapered bottleneck case is inefficient and develops bolt thrust that is undesireable and much greater than it should be.

    it is the cartridge that limits your rifle's pressure ceiling, and in the stock form should not be over loaded. the ackley improved chamber removes alot of the body taper and will therefor handle more pressure. follow your load manual on this one, unless you decide to rechamber to a different round.

    happy trails.
    jh
    Living the urban lifestyle so I can pay my way and for my family's needs, and support my country. And you?
    ".. ask not what your country can do for you, ask what you can do for your country" JFK

  8. #8

    Talking Messin with a good thing

    I'm more than satisfied with the 348 cartridge and I won't mess with it. It'll do what I need it to do and if I want more power, it's just a matter of reaching into the gun safe for it, and I won't have to alter a fantastic win 71 in the process. I have a Marlin 45-70 that's loaded warm but it might get more rest now that there's a new guy on the block. Heck, they're all good...pick one and enjoy it.
    If you like getting kicked by a mule...then you'll "love" shooting my .458.

  9. #9

    Default

    Quote Originally Posted by Maydog View Post
    I have a Marlin 45-70 that's loaded warm but it might get more rest now that there's a new guy on the block.
    Bet on it!!!!!!

    While I've got my beloved 450 Alaskan, I don't own a 71 in 348 because I already have three 358 Winchesters. Ballistics are so similar that I just couldn't justify a 348. Or should I say I couldn't justify KEEPING a 348 around 40 years ago, back when dollars were short and food was needed on the table. Let one slip through my fingers after owning it only a few months, but kept the rent paid.

    Comparing the 348 to the 358 is a good thing in my long experience. I might call my scoped bolt action 358 a 250 yard gun, but I'd stop a little short of that with open sights, even peep sights like I've got on both the other 358's as well as the 450. But I have proven the 358 to be a 200 yard gun, fer sure.

    And you really owe it to yourself to explore cast bullets. I probably put 20 cast bullets down the bores of my 358's for every jacketed bullet, as I would almost certainly do with a 348.

    Your poor old 45-70 is going to get mighty lonely once you have the first dance with your new girlfriend!

  10. #10

    Talking

    Speaking of lonely? My Marlin made several others lonely and now it get's a little taste of it. I agree about the 200-250 yards with open sights...but it just puts hunting back into the equation. Hunting opportunities are getting less and less, so I just want to get more out of them when I go, savour the experience more. With my scoped mag, they can be over fairly fast sometimes, and then I cuss myself out. It can be a long time between seasons as you well know, so I see no need to rush it. If I don't fill my freezer, it's not the end of the world. I think a lot of us find it more important to fill our egos than our freezers, but I'm shifting my priorities...and enjoying it more. Less pressure, you know.
    If you like getting kicked by a mule...then you'll "love" shooting my .458.

  11. #11

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    Quote Originally Posted by Maydog View Post
    ...but it just puts hunting back into the equation. Hunting opportunities are getting less and less, so I just want to get more out of them when I go, savour the experience more. With my scoped mag, they can be over fairly fast sometimes, and then I cuss myself out. It can be a long time between seasons as you well know, so I see no need to rush it. If I don't fill my freezer, it's not the end of the world. I think a lot of us find it more important to fill our egos than our freezers, but I'm shifting my priorities...and enjoying it more. Less pressure, you know.
    Boy, are you ever a setup for using traditional muzzleloaders!!!!! All that is waiting for you plus a whole bunch more. Once I started with the traditionals, and especially building my own stuff, all my other guns have gotten lonely. I've bought six guns in last year, and every single one of them was a traditional muzzleloader. My wife has even gotten hooked and started shooting lots more, and that's a good thing.

  12. #12

    Talking

    Quote Originally Posted by BrownBear View Post
    Boy, are you ever a setup for using traditional muzzleloaders!!!!! All that is waiting for you plus a whole bunch more. Once I started with the traditionals, and especially building my own stuff, all my other guns have gotten lonely. I've bought six guns in last year, and every single one of them was a traditional muzzleloader. My wife has even gotten hooked and started shooting lots more, and that's a good thing.
    I can't argue about that Brown. I've done the muzzleloader thing for a long time, and I guess that's why the levers seem so natural to me, open sights, etc. I have a 58 Zoave, 58 Big Bore, 50 TC, 45 custom. 45 Bounty pistol. I enjoy these also and don't have a problem hunting with them...I just gotta draw the line, lest I'd look like a porqupine with all the rifles strapped to me. Oh yeh, I can't forget about the naval blunderbuss that'll stop a bus either (I still want to shoot that beast).
    If you like getting kicked by a mule...then you'll "love" shooting my .458.

  13. #13

    Default No So

    Quote Originally Posted by tvfinak View Post
    The force on the bolt face follows the simple F = P x A ( force = area x pressure) formula. While a tapered case may bind up in the action at a lower pressures the case doesn't have enough strength to carry any significant load by gripping the case walls tighter. Figure out the area of the case wall and the tensile strength of catridge brass and you can see why this is true.

    You can rebarrel to a case with a smaller head and load to higher pressures but re-chambering won't help the bolt thrust from pressure in the .348 parent case.
    The parent case (348 Win) is a severly tapered case. Tapered cases produce BOLT THRUST . Just as a splitting wedge produces force only in reverse. The straight walled cases like a 450 Alaskan and AI are straighter walled cases. These cases tend to grip the chamber when pressure is applied to the case and the reduction in taper reduces bolt thrust. This is provided you load to the SAME pressure as the parent case. In not sure what the pressure of the 450 Alaskan or AI is. However if you load according to P.O. Ackley's research I feel you would be well within the working limits of your rifle.
    That said, I wouldn't even consider rechambering a M-71 until I had shot a couple hundred rounds through it to see if you really want/need more power; unless it had a bad barrell.
    At close range(under150 yds) on moose sized animals it won't let you down. Enjoy your new rifle !!
    " Americans will never need the 2nd Amendment, until the government tries to take it away."

    On the road of life..... Pot holes keep things interesting !

  14. #14

    Default

    [QUOTE]
    That said, I wouldn't even consider rechambering a M-71 until I had shot a couple hundred rounds through it to see if you really want/need more power; unless it had a bad barrell.
    At close range(under150 yds) on moose sized animals it won't let you down.

    I agree completely. I feel it'll have all the power for the game I intend to hunt with it (blackies, mulies, antelope, elk and deer. I don't know if I can get my loads worked up in time for my upcoming elk hunt, but I'll try.
    If you like getting kicked by a mule...then you'll "love" shooting my .458.

  15. #15
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    Default Not quite like it appears

    The primary thrust on a bolt face is generated by the pressure in the case acting against the area inside the case parallel to the bolt face. The cross sectional area of the case in relatively small and brass is realtively weak in tensile strength. Even if the walls are straight and the brass grips the walls of the chamber the case is not strong enough to prevent the head of the case from being forced against the face of the bolt by the internal pressure. This is why headspace is important- if the case walls grip the chamber and there is excess headspace the case simply stretches until it is restrained by the bolt face. When fire-forming you oil the cases so they will slide back against the bolt face and blow the shoulder out instead of the case stretching.

    A tapered case will slide back and expand and wedge against the bolt face and make the action harder to open but a tapered case just doesn't increase the thrust on the bolt to any significant degree.

    Years ago the relatively weak Krag action was used for a number of small wildcat cartridges that oerated a relatively high pressures. This is possible because of the much smaller bolt thrust produced by the small cases. You can put a .22 Hornet on a Krag action and load it to 55,000 psi safely while the orginal .30-40 cartridge operating at that pressure would quickly break something.


    Quote Originally Posted by brav01 View Post
    The parent case (348 Win) is a severly tapered case. Tapered cases produce BOLT THRUST . Just as a splitting wedge produces force only in reverse. The straight walled cases like a 450 Alaskan and AI are straighter walled cases. These cases tend to grip the chamber when pressure is applied to the case and the reduction in taper reduces bolt thrust. This is provided you load to the SAME pressure as the parent case. In not sure what the pressure of the 450 Alaskan or AI is. However if you load according to P.O. Ackley's research I feel you would be well within the working limits of your rifle.
    That said, I wouldn't even consider rechambering a M-71 until I had shot a couple hundred rounds through it to see if you really want/need more power; unless it had a bad barrell.
    At close range(under150 yds) on moose sized animals it won't let you down. Enjoy your new rifle !!
    Living the urban lifestyle so I can pay my way and for my family's needs, and support my country. And you?
    ".. ask not what your country can do for you, ask what you can do for your country" JFK

  16. #16

    Default Not so

    Quote Originally Posted by tvfinak View Post
    The primary thrust on a bolt face is generated by the pressure in the case acting against the area inside the case parallel to the bolt face. The cross sectional area of the case in relatively small and brass is realtively weak in tensile strength. Even if the walls are straight and the brass grips the walls of the chamber the case is not strong enough to prevent the head of the case from being forced against the face of the bolt by the internal pressure. This is why headspace is important- if the case walls grip the chamber and there is excess headspace the case simply stretches until it is restrained by the bolt face. When fire-forming you oil the cases so they will slide back against the bolt face and blow the shoulder out instead of the case stretching.

    A tapered case will slide back and expand and wedge against the bolt face and make the action harder to open but a tapered case just doesn't increase the thrust on the bolt to any significant degree.

    Years ago the relatively weak Krag action was used for a number of small wildcat cartridges that oerated a relatively high pressures. This is possible because of the much smaller bolt thrust produced by the small cases. You can put a .22 Hornet on a Krag action and load it to 55,000 psi safely while the orginal .30-40 cartridge operating at that pressure would quickly break something.
    When the 348 was designed it was a rimmed cartridge; IT HEADSPACES ON THE RIM !! The rim is supported and the case walls go where they expand to. The fact that straight walled cases provide less bolt thrust is more than documented by both Gibbs and Ackley.
    Common sense and the physical properties should tell you that if a case is forced backwards instead of outwards it produces MORE bolt thrust.
    That's why the bullet weight and velocities can go up and still not exceed the SAMMI pressure of this rifle's original cartridge.
    AND; I'm not aware of any reloading manual that says to insert an oiled round into a chamber and fire to fireform a case; The chances of hydraulic pressure increases cause this to be a very dangerous action. It could destroy the firearm and the shooters as well. Most fireforming is done with a charge of powder, or powder and cream of wheat (over powder wadding).
    " Americans will never need the 2nd Amendment, until the government tries to take it away."

    On the road of life..... Pot holes keep things interesting !

  17. #17
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    Default Basic engineering

    Head space is an issue regardless of cartridge design because the case isn't strong enough to restrain the backward thrust - the case simply stretches until it is stopped by the bolt face. High pressure brass rifle cases simply aren't strong enough to prevent the pressure against the bolt face. If we were dealing with strong steel cases that didn't stretch and could contain the pressure and prevent the head of the case from being thrust back agains the bolt face your assumption would be correct- but we are dealing with weak brass cases that stretch easily.

    For low pressure black powder loads the case design probably does have some effect. A .30-30 loaded with black powder probably has more thrust than a .38-55 loaded to the same pressure - but in modern guns the thrust in both cases is so low it is insignificant. For older weaker guns and steel it may have been an actual issue.

    Lightly oiling your cases when fire forming with bullets is a well known practice - it allows the case to expand to fit the chamber rather than gripping the walls and stretching in some areas. With a filler the pressures are so low it dosen't make much difference but it can make a mess.

    I'll check my reference books and see what Gibbs and Ackley have to say. There could have been some measurment errors- unfortuantley those guys didn't have the modern tools to record things that we have today.

    I'll also see if I have a sectioned .348 case laying around so I can get a cross sectional area. Finding the tensile yield strength of brass should not be hard so calculating the maximum restraint by the cartridge design should be easy. I'll show you the figures and why the case design doesn't matter that much.

    Quote Originally Posted by brav01 View Post
    When the 348 was designed it was a rimmed cartridge; IT HEADSPACES ON THE RIM !! The rim is supported and the case walls go where they expand to. The fact that straight walled cases provide less bolt thrust is more than documented by both Gibbs and Ackley.
    Common sense and the physical properties should tell you that if a case is forced backwards instead of outwards it produces MORE bolt thrust.
    That's why the bullet weight and velocities can go up and still not exceed the SAMMI pressure of this rifle's original cartridge.
    AND; I'm not aware of any reloading manual that says to insert an oiled round into a chamber and fire to fireform a case; The chances of hydraulic pressure increases cause this to be a very dangerous action. It could destroy the firearm and the shooters as well. Most fireforming is done with a charge of powder, or powder and cream of wheat (over powder wadding).
    Living the urban lifestyle so I can pay my way and for my family's needs, and support my country. And you?
    ".. ask not what your country can do for you, ask what you can do for your country" JFK

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