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Thread: Key holing everything! WTH?!

  1. #31
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    What is the twist rate of the barrel? What bullet weights were you shooting specifically?

  2. #32
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    It is not unusual to see military barrels condemned around the 5k round mark via errosion gauging

  3. #33
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    Regardless of how clean you think your muzzle and crown is I highly recommend pulling the flash hider or muzzle brake. Cleaning the crown and shooting the gun w/o anything attached to the muzzle and let me know your results. Usually the gun will shoot like a shotgun w/buckshot and a cylinder choke at 25yds far before it'll keyhole.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

  4. #34
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    Something isn't right here.... only 5k through it and out of the blue it's keyholing when it hadn't before???

    Is it possible it had been doing this much longer but wasn't shot on paper?

    And can we quit citing that retarded Vurhwhappinblog retarded barrel destruction nonsense? This site is better than that.
    Last edited by markm; 02-18-14 at 08:07.
    "You people have too much time on your hands." - scottryan

  5. #35
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    Unless you can put an eyeball on the barrel's throat, gas port, and crown (using a borescope) you'll just be guessing as to the barrel's condition. You may get lucky or not.

    There are a number of reasons for bullets to keyhole that badly at 25 yards/Meters: there's not enough rifling to stabilize the projos; the bullets you're shooting are too long for the twist rate; the barrel's been otherwise damaged; or something's wildly throwing off harmonics (the bullets may be hitting something or the flash suppressor might be cracked between slots or tines).

  6. #36
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    The OP mentioned a Vortex FH. We did have a rifle that was inexplicably keyholing at even close ranges during a carbine class. We pulled the Vortex off of it and reshot it with no problems. First guess was muzzle strikes on the Vortex, however we weren't investing a lot of troubleshooting time, just getting it back into running shape for class. I'd look the whole FH over to make sure there's no distortion on the prongs before investing in a new barrel.

  7. #37
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    That is strange. I have a Sabre 14.5 middy that will shoot nearly MOA with Matchkings, but can literally shoot 10" plus groups a 25 yards with flat base 55 gr Hornady Soft Points. It's the weirdest damned thing. Clint, here, thinks the bore opens up a few thowie near the muzzle.
    "You people have too much time on your hands." - scottryan

  8. #38
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    Quote Originally Posted by Blankwaffe View Post
    Is there a large amount of carbon build up at the muzzle in the FH?

    Here is a thread that Robb Jensen/gotm4 posted pics and info on the subject:

    https://www.m4carbine.net/showthread...-AR15-s-barrel

    May not be the issue but worth a look.
    No. No major buildup at the muzzle. Recently switched from a spikes tactical dynacomp to a smith vortex because I was contemplating possible baffle strikes when leaving the barrel. I have had this same issue even with NO muzzle device.
    -BTO-

  9. #39
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    Quote Originally Posted by eodinert View Post
    What is the twist rate of the barrel? What bullet weights were you shooting specifically?
    1:9 non chrome lined barrel. 95% of it is 55gr with the other being 62gr. FMJ, HP, polymer tipped, soft point, even green tip LAP.
    -BTO-

  10. #40
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    I'd see if a bolt gun builder in your area could pin guage the bore. Twist is plenty fast enough to stabilize all those bullets. I'd bet you have an inconsistent bore diameter.
    "You people have too much time on your hands." - scottryan

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