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Thread: Bullet Keyholing

  1. #11
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    Quote Originally Posted by Tornado_Racing View Post
    Does this mean my barrel is shot out and has to be replaced after only 6k?
    Yep.

    I know your accuracy standards are probably different than mine and you don't consider a barrel shot out until it keyholes, but I would have, for my target shooting purposes, considered it a tomato stake probably around 3,500 round when it probably wouldn't have held a 3.5 MOA 10 ring.

    Mil Standard is what, about 5MOA?

  2. #12
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    If it were me I would just clean it and shoot it with new ammo and see if that fixes it.

    If you are still getting keyholes, than I would buy a new barrel. I would not speed a lot of time and money trying to fix a chrome molly barrel with 6K down the tube.

  3. #13
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    Would I loose my grouping and noticed keyholing in a week or should it develope over time?

    Last week I was grouping well out to 50 yards just pending hot/cold barrel and ammo used. The XM193 (hot barrel) and 75 grain TAP (cold barrel) grouped within a half dollar (no magnification as my AR has an Aimpoint H1).

    ETA: Sorry for the half dollar comparision as I do not fully understand 1-3 MOA, sub MOA, etc.
    Last edited by Tornado_Racing; 05-10-10 at 13:33.

  4. #14
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    Quote Originally Posted by 5pins View Post
    If it were me I would just clean it and shoot it with new ammo and see if that fixes it.

    If you are still getting keyholes, than I would buy a new barrel. I would not speed a lot of time and money trying to fix a chrome molly barrel with 6K down the tube.
    When you suggest new ammo, do you mean steel or brass? I try to alternate between steel and brass hence the 3k each.

  5. #15
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    Quote Originally Posted by Tornado_Racing View Post
    Would I loose my grouping and noticed keyholing in a week or should it develope over time?

    Last week I was grouping well out to 50 yards just pending hot/cold barrel and ammo used. The XM193 (hot barrel) and 75 grain TAP (cold barrel) grouped within a half dollar (no magnification as my AR has an Aimpoint H1).

    Sorry for the half dollar comparision as I do not fully understand 1-3 MOA, sub MOA, etc.
    In a nutshell 1 MOA (minute of angle) is basically a 1 inch pattern at 100 yards. That's rounded off of course. For a more detailed explanation read here.
    Steve

  6. #16
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    Quote Originally Posted by SteveL View Post
    In a nutshell 1 MOA (minute of angle) is basically a 1 inch pattern at 100 yards. That's rounded off of course. For a more detailed explanation read here.
    At 50 yards it would be .5 MOA or sub MOA and my grouping would roughly be 3.0 MOA @ 100 yards?
    Last edited by Tornado_Racing; 05-10-10 at 13:43.

  7. #17
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    Quote Originally Posted by ralph View Post
    It is indeed possible the barrel is toast..I did the same thing with my first AR,(bushmaster) lots of mag dumps..5000 rnds later accuracy is gone, keyholing, yup, just a few mag dumps too many. In my case, a new barrel and I was back in business..Now, to the OP..you said in your post the barrel in question was a chrome moly barrel. If it's not chrome lined, you may be able to save it..you'd have to pull the barrel and have it rechambered..very probably the throat is toast,Usually the rifling itself is in good shape, If the throat it self is gone, rechambering/rebarreling are your only options. I don't know how much this would cost, But if it was me,I'd use this opportunity to upgrade to a higher quality barrel if possible. I'd consider either a CHF barrel from DD, BCM, or a Noveske barrel, and maybe back off the mag dumps..
    If indeed I need a new barrel I will go with the DD CHF 14.5" Lightweight, VLTOR .625 Lo Pro GB, and a PWS FSC 556 Comp.
    Last edited by Tornado_Racing; 05-10-10 at 13:58.

  8. #18
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    More like inside a 3" circle with good ammo.

    A gun that shoots greater than 3MOA is a failed gun that will not be accepted by gov't, so 3MOA is what's called the threshold (minimum performance level), with 1MOA being the objective (ideal performance level). Most fall well inside the spec, and the median for fielded gov't guns is around 2MOA.

    Quality of ammo will affect your print. If you're testing, spend the money to use match grade ammo in the 55-62gr range.

    Quality of the shooter affects it even more, so there's that....

    Your barrel still may or not be ganked. I'm sorta wondering if shooting ammo over 62gr in a 1-in-9 barrel may have contributed to what you're seeing. I don't know enough to say that shooting the heavier stuff will wear the barrel faster, but bullets longer/heavier than 62gr don't stabilize well in your twist rate.
    Contractor scum, AAV

  9. #19
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    Quote Originally Posted by Riverine View Post
    More like inside a 3" circle with good ammo.

    A gun that shoots greater than 3MOA is a failed gun that will not be accepted by gov't, so 3MOA is what's called the threshold (minimum performance level), with 1MOA being the objective (ideal performance level). Most fall well inside the spec, and the median for fielded gov't guns is around 2MOA.

    Quality of ammo will affect your print. If you're testing, spend the money to use match grade ammo in the 55-62gr range.

    Quality of the shooter affects it even more, so there's that....

    Your barrel still may or not be ganked. I'm sorta wondering if shooting ammo over 62gr in a 1-in-9 barrel may have contributed to what you're seeing. I don't know enough to say that shooting the heavier stuff will wear the barrel faster, but bullets longer/heavier than 62gr don't stabilize well in your twist rate.
    Gotcha............Most of what I have run through is 55 grain. Only 200 rounds of 62 grain M855, 10 rounds of 64 grain M856, and 10 rounds of 75 grain TAP.

  10. #20
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    Yeah, that's negligible. Unless you coated them with sandpaper!

    WHAT AREN'T YOU TELLING US!?!?
    Contractor scum, AAV

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