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Thread: Bent Barrel

  1. #11
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    Nope. The test barrel makers use (or at least, used to use back when it was done mostly by hand) was a big window with windowframes in it.

    Look down the bore, out the window, into the sky. Move the barrel until you have the line of a pane frame in sight.

    the line of the frame, running down the bore, will show if the bore/barrel is straight, or bent.

    The old hands would sight a barrel, then use a barrel press to straighten it, and check again. In the better shops, if it took more then a couple of attempts to straighten it, the shop foreman would find out who the klutz was; the straightener or someone further up the line.

    Look out your window, with something straight in view. use that, and get back to us. If you have any questions, use a barrel you know to be straight as a comparison.

  2. #12
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    Bent Barrel

    Understand that there aren't to many methods available that can straighten a of of steel, rod, tube, or barrel without knocking it out of roundness.

    I'm not sure if there is a roundness, or concentric it's specification to a barrel (I'm sure there as as designed by the OEM)...or additionally a straightness specification.

    I just personally don't know of any methods that won't offset another dimension in trying to straighten.

    If the ID of the barrel gets a flat spot or another form of indentation from OD input in trying to straighten...it may straighten the shit out if it. But make it dangerous to fire. I.e, the bullet hits a flat spot as it passes down the bore.

    Then you and the barrel are both ****ed up.

    I'd contact the OEM to see about warranty on something like this before letting a "competent" smith "fix" it.

    Just my .02...and I make Tubes, rods, shafts, and bars for a living...just not barrels.

  3. #13
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    A cleaning rod won't work. You need something that goes into the barrel and fits inside almost perfectly. A real .MIL gage does this and will stop even if the barrel is dirty.



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  4. #14
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    You need one of these... or one from a different manufacturer.

    http://shop.pacifictoolandgauge.com/...products_id=56
    US Army Infantry 2008-2012
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  5. #15
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    Bent Barrel

    Another answer to the OP is that zeroing an aimpoint at 100 isn't a viable alternative. Zero at a 100 won't mean a thing at 200if the bullets zinging to the right as well as dropping. It will be that much further right at 200 and beyond.

    Zeroing is only to account for ballistic drop (wind and other environmentals too) and essentially a perfectly straight barrel. So that from 100-200 you only have a vertical or minimal wind shift left right for such variables.

    Again, just my .02

  6. #16
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    Are you near Douglas or Savage? They have/had barrel straightening presses.

  7. #17
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    Quote Originally Posted by jwperry View Post
    Visually, the curve in the barrel looks to start at/around the necking up of the barrel to the gas block and continues to the muzzle. Total deflection being right around 1/8" (estimate using the ole' MK1 eye ball).
    That damn good for your "ole'MK1 eye ball". Using inverse tangent of 8"/900" (25 yards), an 8" worth of deflection at 25 yards, equates to angle of ~1/2 degree. Using similiar triangles, 8"/900" = x/14.5", with x - the barrel deflection coming out to ~0.129".

    So just 3 thousandth off. Might have to re-cal your MK1 eye ball.

    Quote Originally Posted by jwperry View Post
    Is there any safe way to straighten out this portion of the barrel so that I can have enough adjustment to have a 100 yard zero or do I have $500 of wasted steel taking up space in my upper?
    I'm unfamiliar with straightening presses, but if you were planning to DIY bend it back with weights, it's probably more trouble than it's worth. I did a quick calculation on bending stress. Assuming a constant 0.75" bore, 14.5" long, fully clamped on the opposite end of the force, solve for the force required to yield the barrel. Depending on the yield strength of the barrel in shear, 416 stainless can range from 20ksi to 80ksi based on heat treatment or lack thereof, which means the required force can range from 460 lbs to 1841 lbs. Keep in mind that's a really simplified hand calc analysis, and even if you could do it, you'd have to be careful of the creep rate, period you load at yield as it deforms. Assuming you had the weights, and rig to do it, if you had a laser bore guide you could visual check it that way without deflection transducers.

  8. #18
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    If I had to guess I'd have to say its less likely a bent barrel and more likely either a slight rail misalignment, or possibly a slightly out of true receiver face causing deflection between the barrel and rail mounted sight. To fix you can either true the receiver face or very slightly realign the rail.
    Last edited by SA80Dan; 04-04-13 at 18:02.
    Dan

  9. #19
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    I had a bent barrel once. I wanted to order a custom barrel from a reputable manufacturer but they wouldn't do the custom work themselves. They referred me to a reputable gunsmith who was one of their distributers. They suggested I order through the distributer and have them do the work. When I got the barrel the symptoms were just like yours, windage maxed out and crap groups. The bend was visible by removing the barrel and looking through the chamber and it also visibly wobbled when rolled on a flat surface. I contacted the manufacturer and at first they tried to say the gunsmithing voided the warranty but after forwarding the original e-mails where they told me to order through this distributer and have them do the work they relented and replaced the barrel. I was still out about $150 in custom work but at least it wasn't a total loss.

    I recommend contacting the manufacturer.

  10. #20
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    i have a shotgun in my posession that was ran over by a tractor many years ago and bent the barrell. my dad got it for nothing and ended up taking the barrell off and plugging one end and filled the barrel full of fine sand and plugged the other end. then proceeded to stick it between two oak tree's and pull on it very slowly until he couldn't pull it anymore. the barrel would only go back to where it was straight and wouldn't go anymore. i don't know if this would be safe on a .223 barrel and i am talking about a more forgiving shotgun barrel but i can't see where this thing was ever bent.

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