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bbl life limits for miliary guns?

Discussion in 'Shooting Related Threads' started by joe kuhn, Dec 25, 2008.

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  1. joe kuhn

    joe kuhn Furry Lives Matter TS Supporters

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    Those boys shoot alot of rounds. My questions are:

    1. What are the life limits on their barrels and how were they determined?

    2. Is there a smooth bore bbl in the military with established life limits?

    Thanks, Joe
     
  2. joe kuhn

    joe kuhn Furry Lives Matter TS Supporters

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    And question 2?
     
  3. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    An old friend in CA taught me to reload my rifle cartridges and how to accurize my hunting rifles. He said the same things as PBB does too. Another thing he said was the higher chamber pressures would create more heat and wash out the throat area quicker even with hunting rifles.

    Mike, next time your at the P factory you might ask about some of the questions I ask below? I think it would be extremely interesting to know the process they use?

    I'm wondering about the "proofing" method manufacturers use to proof shotgun actions and barrels. Some estimates I've read here say some proof loads exceed SAMMI safe working pressures by 5 times that amount! The question I have is this. How do we know after such a strain is placed on said receiver/barrel, is it possible that the test may do more harm than good on a few barrels/chambers, long term? It's off to the market if it stands one such test the way I understand the process. I know first hand metal manufacturers can cast metals with impurities embedded in the metal itself at times. Would this "proof" test show any such impurities? Not every time in my opinion and past experience with working with metals say it wouldn't show up, every time. The only possible way to rule out said impurities would be to X-ray the metal before the machining or hammering process began. Just because a pipe can stand intensely high pressure once doesn't mean it won't fail with repeated high pressure abuse. Do barrel/receiver makers X-ray in addition to proofing the final result?

    Hap
     
  4. Haskins Bill

    Haskins Bill TS Member

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    The main gun on the Abrahms tank is a smooth bore.
     
  5. TOOLMAKER 251

    TOOLMAKER 251 Active Member

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    When the US was conducting tests on the EM2 rifle back in the 50's Springfield armory determined the barrel was good for 10-15,000 rounds. When the Army was looking for a new sniper rifle the requirement was for a gun that would hold .35MOA at 100 yards for 10,000 rounds fired from a machine rest. They were supprised that after 10,000 rounds that accuracy improved slightly. A few barrels were tested up to 20,000 rounds and never exceded the .35MOA requirement. (major John Mende Ret.) This is a 7.62x51 round which has around 60,000 PSI.
     
  6. KENENT1

    KENENT1 Active Member

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    a friend had an old sks from some russian breg country, and the rifelng was warn out half way down the barrel, and we could pretty much keep then on a paper plate @ 100 yds.....almost all of 'em.

    I think he paid $60.00 for it.


    tony
     
  7. Shooting Coach

    Shooting Coach Well-Known Member

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    Depending on the barrel, the military match calibers of yesterday, the revered 30/06 and fantastic 7.62, were good for Match accuracy up to 8,000 rounds or so. Practice rifles would give about 1.5 MOA at 12,000 rounds.

    The 5.56 with the fast twist and heavy bullets go about 4,000 rounds. Rapid fire eats the throat. The 5.56 is freebored for the heavy bullet 600 yard load. This is not good for the throat either.

    On a summer day at Perry, any of the Classic Service Match Rifles, Garand, M1-A, or AR-15 will burn you if you touch the barrels right after the rapid fire stage.

    The 7.62 is still used for some Service Match Rifles, but the easier to maintain and re-barrel AR-15 has about taken over at Perry.

    There is a 100+ gr load for the 5.56 round that is effective and accurate at ONE THOUSAND YARDS.
     
  8. TOOLMAKER 251

    TOOLMAKER 251 Active Member

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    Mike, You can learn something new today. Look up US army M24 sniper weapon system. The article will be under WWW.snipercentral.com These barrels have the 5R rifling (polygonal) I have a 700 Remington with a Schneider 5R barrel with a little over 2,200 rounds thru the tube. Bore scoping shows very little throat erosion.
     
  9. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    Thanks Mike, I suspected none X-rayed. I've worked in steel mills producing all kinds of steel products and know some of the inner workings fairly well. Most is great steel as proved with line tests but some bad does slip through once in a while. My experience in using some of those various grades of steel in the field for various applications makes me cautious. That caution would require me to X-ray steel for receivers and barrels if I was in charge of building them with total confidence and my livelihood depended on it. Hap
     
  10. g7777777

    g7777777 TS Supporters TS Supporters

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    As stated above- how accurate is accurate enough?

    They have put over 30,000 rounds through M16 barrels and determined that although accuracy decreased- it wasnt that much

    If you are shooting at peron or animal or most things- it wont matter- you never need to replace a barrel- throat wear or not

    Exceptions- headspace or where tenths of an inch in accuracy matter

    sometimes just recrowning a muzzle will decrease accuracy an amazing amount

    regards from Iowa

    Gene
     
  11. TOOLMAKER 251

    TOOLMAKER 251 Active Member

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    Mike, When I said my throat was worn very little, the bore scope showed wear typical of a non 5R rifled barrel that had 100 rounds or less on it. Also when freshining up a throat you don't have to take a 1/2 off the shoulder. 1/16 or less is ok. I have many barrels for my Hall action in 6mm (6ppc) throats run about .030 long. 1 Shilen barrel which I had over 1,000 rounds thru it agg. a .191 (5 targets 5 shots each) Do some research on the 5R rifling. The information was furnished thru major John Mende who was the manager of the development of the M24 weapon system. Shooting coach, who is using a 100 grain bullet in a 5.56 and having great success at 1000 yards. A bullet of that weight fired from a 5.56 would become subsonic long before reaching 1,000. I spoke to a friend of mine, John Sylvester who was the shooter of the year in 2004 at camp Perry and he knows of no one using it in a 5.56 maybe you are thinking of someone shooting it in a 22-250?
     
  12. Shooting Coach

    Shooting Coach Well-Known Member

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    Dear Toolmaker

    This load exists and is available. I did not say folks were using it with great success. It has been tested, and can be obtained, along with suitable barrels.

    I did say it was effective and accurate to 1000 yards. Obviously, it will have a rainbow trajectory.

    It does allow the 5.56 to be more effective than a falling pebble at extreme range.

    It seems to me the 80 gr bullet used in the 600 yard load is about as far as one can go with commonly available arms and ammo.
     
  13. TOOLMAKER 251

    TOOLMAKER 251 Active Member

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    Shooting Coach, I am aware of 2 Mfg. of the 100 gr. .223 but what would the velocity be at 900-1,000 yards? As your aware a bullet traveling at supersonic speed when falling to subsonic becomes unstable. I myself don't see how a bullet of this weight seated 3/4" into the case can be launched at a speed where it could still be supersonic at that range. I could be wrong, it will not be the 1st. time or the last.
     
  14. TOOLMAKER 251

    TOOLMAKER 251 Active Member

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    Mike, Go to www.snipersparadise.com and read the june 2001 article by Boots Obermeyer. You will gain alot of info about rifling, barrel's and pressures vs bullet weight. I know you heard of him, he is considered the most knowledgeable rifle barrel maker in the US.
     
  15. TOOLMAKER 251

    TOOLMAKER 251 Active Member

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    Sarge, I beg to differ with you on little serious testing of barrel life. In the early 50's our military did extensive testing of the US T25 rifle which evolved into the M14. Also much testing was done on the EM2, and FN in our quest for a new light service rifle.
     
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