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Thread: Key holing everything! WTH?!

  1. #41
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    Quote Originally Posted by Robb Jensen View Post
    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.
    Attached is a "group" from a couple weeks ago with no muzzle device attached. The muzzle was thoroughly cleaned and inspected as well as I could.
    Attached Images Attached Images
    Last edited by funkybassplayer; 02-18-14 at 10:48.
    -BTO-

  2. #42
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    How much were the groups opening up before it started key holing? That looks like an 8 inch target, and I know this probably isn't deliberate aimed fire, but that makes this spread is about 24 MOA... If it's doing it with no FH, barrel is simply done. 5K rounds seems fast, but a non chrome lined barrel is definitely going to wear faster than expected, especially with accelerated firing.
    "SEND IT" happens to be my trigger words...

  3. #43
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    Quote Originally Posted by markm View Post
    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?
    All shooting has been done of paper, cardboard, some sort of target.

    Quote Originally Posted by sinister View Post
    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).
    Quote Originally Posted by B+Shooter View Post
    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.
    The vortex FH is brand new and I was having the same issue with the dynacomp that I had been using even before all of the "sesame seed holing" began.
    -BTO-

  4. #44
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    Quote Originally Posted by _Stormin_ View Post
    How much were the groups opening up before it started key holing? That looks like an 8 inch target, and I know this probably isn't deliberate aimed fire, but that makes this spread is about 24 MOA... If it's doing it with no FH, barrel is simply done. 5K rounds seems fast, but a non chrome lined barrel is definitely going to wear faster than expected, especially with accelerated firing.
    The groups weren't really opening up that I saw. That target was shot off hand from about 25yds with DD fixed iron sights (love em) and it was not deliberately aimed. Shot off bags with the iron sights I can still get 5rds in about a 1.5" group at 50yds. Granted I'm not sharp shooter but I think that's a respectable group for factory ammo.
    -BTO-

  5. #45
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    I was goin through the pics of targets that I have and found this one.


    This is from around the time I started to see the key holing begin. As you can see there are a number of holes showing proper bullet impact and then a bunch of profile impacts.

    I believe this was 2 magazines worth sent down range and I began to assume that the normal impacts were from the cold barrel and then as the barrel began to heat up then the tumbling began.

    Any thoughts on this? And again I am really appreciating all of the input and knowledge that y'all are offering up!
    -BTO-

  6. #46
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    A word on choosing a barrel or upper. There are more factors at play than just the material the barrel is made out of, although that is important too. I will mention two important ones.

    Gas port size- you don't want your rifle to be overgassed. It can cause problems down the road. Most companies do over-gas their rifles because they want them to work with crappy ammo. Which is the wrong fix to an almost non problem. Pick a company that you are assured has the proper gas port size. DD and BCM are two of them.

    Quality control.- You want a company that has high standards here. Very many companies do not invest in checking chamber dimensions, bore uniformity. They do not high pressure test nor Magnetic particle test their barrels. ON the other hand, I know that BCM meticulously inspects every upper, lower, barrel, bolt, carrier, etc that is made for them, and HP/MP EVERY barrel and bolt.

    Since I learned the efforts Paul at BCM goes to to make sure his product is the best it can be, I have changed my outlook on choosing a rifle. There are a few I trust more than others. BCM, DD, Nov are a few of them. Sadly most companies don't put the effort. Including a few mentioned on this thread.
    Last edited by Shiz; 03-04-14 at 22:25.

  7. #47
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    I have a 7.5" 5.56 barrel used on an M16 lower as a 'blast O tron' that I've replaced. It likely had 5k to 10k through it (as well as 22LR). It started key holing like yours. The rifling is almost non-existent. The gas port is also flame cut on the inner bore significantly.

    Either your barrel is somehow copper fouled reducing the effect of existing rifling or the rifling is worn down.

    Don't use a suppressor on this either...

    I'm guessing the barrel is toast. Sorry.

  8. #48
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    Quote Originally Posted by funkybassplayer View Post
    I believe this was 2 magazines worth sent down range and I began to assume that the normal impacts were from the cold barrel and then as the barrel began to heat up then the tumbling began.

    Any thoughts on this? And again I am really appreciating all of the input and knowledge that y'all are offering up!
    You should have someone spot for you and watch exactly when the bullets are going wonky. In any case, I'd dump this barrel quick.
    "You people have too much time on your hands." - scottryan

  9. #49
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    Key-holing bullets without a muzzle device of any kind indicates bullets are too heavy or simply that the barrel's toast.

    Low-grade mass-produced barrels coupled with abuse can ruin a barrel in less than 2,000 rounds. I've seen some custom barrels from mass blanks do screaming tight groups for about 1200 rounds before any kind of precision goes completely out the window.

  10. #50
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    Ok guys. Just placed my order for one of BCM's BHF 14.5" KMR uppers. Also gonna get one of thier bCG's. Heard nothing but good stuff about BCM so gonna take the plunge. Update and range report to come shortly, hopefully.


    -BTO-
    -BTO-

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