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h2oskier
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Posted: 1/14/2012 9:04:24 PM
[Last Edit: 1/22/2012 4:40:54 PM by h2oskier]

THE IMAGE ABOVE IS A PAID ADVERTISEMENT
I took my just built Ar15 out to the range today. I shot about 150 rounds through it dialing in the aimpoint ML2 and then just having fun. The target was at 50 yards. I noticed that 5 of the bullets keyholed the target or went sidewaysd through the target. My upper is a Larue DMR 16" stealth with 1:8 twist. I unfortunatly used 4 different types of ammo so I am unable to pinpoint if it was a ammo issue. Any help would be appriciated.

Ammo used:
Remingtom UMC 55gr
Black Hills 55gr FMJ
Winchester 62 gr FMJ
ASYM 75 gr tactical match grade (tightest grouping)

MTNmyMag
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Posted: 1/14/2012 9:15:49 PM
not sure could be bad ammo but that is weird
Big-Bore
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Posted: 1/14/2012 9:17:23 PM
A 1:8 twist with 55 gr. bullets is a very marginal combination. It is a whole lot better than a 1:7 but still, a 1:8 is pretty fast for a 55 gr. bullet. A 55 should stabilize OK in a 1:8 but a 1:9 or 1:12 would be better, and with UMC being reportedly slightly under powered, my money lies with the UMC ammo being the culprit.
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usmcscout
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Posted: 1/14/2012 9:17:59 PM
Crooked barrel
"Semper FI"
h2oskier
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Posted: 1/14/2012 9:23:39 PM
Originally Posted By Big-Bore:
A 1:8 twist with 55 gr. bullets is a very marginal combination. It is a whole lot better than a 1:7 but still, a 1:8 is pretty fast for a 55 gr. bullet. A 55 should stabilize OK in a 1:8 but a 1:9 or 1:12 would be better, and with UMC being reportedly slightly under powered, my money lies with the UMC ammo being the culprit.





That is what I suspected also. I need to go back and be more specific with ammo during each 20 minute shooting session.
458winmag
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Posted: 1/14/2012 9:24:34 PM
Who was shooting next to you?
h2oskier
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Posted: 1/14/2012 9:32:33 PM
Originally Posted By 458winmag:
Who was shooting next to you?


Pistols shooting 25 yard targets on both sides directly next to me. It was a miss mash beyound that.
Dano523
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Posted: 1/14/2012 10:44:03 PM
Double check the FS being loose, with possibly a loose FS that was causing bullet strikes to the FS, with and end result of a few tumbled rounds.

Short of that, funky ammo with some of the bullets a tad cross width under sized, barrel fouled with too much copper to cause the problem, or 5 stray rounds from another shooter.


So on that note, double check the FS to make sure it tight, has no bullet strike, and even check the amount of copper that you are pulling from the barrel rifling when using something like sweets bore solvent to see if the build up is abnormal for only 150 rounds (us did clean the barrel fully before shooting, correct?).
Posted By PlaymoreMinds:

'Twas not the <cough> sweet and innocent <cough> PlaymoreMinds...

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iNeXile556
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Posted: 1/14/2012 10:46:23 PM
[Last Edit: 1/14/2012 10:48:56 PM by iNeXile556]
55gr is just fine for 1:7, instability is from too slow a twist not too fast. I shoot 40-80gr from my 1:7 without a problem.

I'll wager, and this is no reflection on you, that the keyhole rounds are more likely from ricochet round off the ground.
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markfall
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Posted: 1/14/2012 11:16:18 PM

Originally Posted By iNeXile556:
55gr is just fine for 1:7, instability is from too slow a twist not too fast. I shoot 40-80gr from my 1:7 without a problem.

I'll wager, and this is no reflection on you, that the keyhole rounds are more likely from ricochet round off the ground.

Ricochets would leave more deformed holes than that.
We only got two things from prohibition: the NFA of 1934 and NASCAR.

and I hate both.
h2oskier
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Posted: 1/14/2012 11:16:30 PM
Originally Posted By Dano523:
Double check the FS being loose, with possibly a loose FS that was causing bullet strikes to the FS, with and end result of a few tumbled rounds.

Short of that, funky ammo with some of the bullets a tad cross width under sized, barrel fouled with too much copper to cause the problem, or 5 stray rounds from another shooter.


So on that note, double check the FS to make sure it tight, has no bullet strike, and even check the amount of copper that you are pulling from the barrel rifling when using something like sweets bore solvent to see if the build up is abnormal for only 150 rounds (us did clean the barrel fully before shooting, correct?).


I did not clean my new barrel before shooting.....Is that a problem?
458winmag
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Posted: 1/14/2012 11:17:04 PM
Originally Posted By Dano523:
Double check the FS being loose, with possibly a loose FS that was causing bullet strikes to the FS, with and end result of a few tumbled rounds.

Short of that, funky ammo with some of the bullets a tad cross width under sized, barrel fouled with too much copper to cause the problem, or 5 stray rounds from another shooter.


So on that note, double check the FS to make sure it tight, has no bullet strike, and even check the amount of copper that you are pulling from the barrel rifling when using something like sweets bore solvent to see if the build up is abnormal for only 150 rounds (us did clean the barrel fully before shooting, correct?).


Did you meen FH?
458winmag
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Posted: 1/14/2012 11:20:27 PM
Originally Posted By markfall:

Originally Posted By iNeXile556:
55gr is just fine for 1:7, instability is from too slow a twist not too fast. I shoot 40-80gr from my 1:7 without a problem.

I'll wager, and this is no reflection on you, that the keyhole rounds are more likely from ricochet round off the ground.

Ricochets would leave more deformed holes than that.


We have a winner
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Posted: 1/14/2012 11:27:04 PM

Originally Posted By h2oskier:
Originally Posted By Big-Bore:
A 1:8 twist with 55 gr. bullets is a very marginal combination. It is a whole lot better than a 1:7 but still, a 1:8 is pretty fast for a 55 gr. bullet. A 55 should stabilize OK in a 1:8 but a 1:9 or 1:12 would be better, and with UMC being reportedly slightly under powered, my money lies with the UMC ammo being the culprit.





That is what I suspected also. I need to go back and be more specific with ammo during each 20 minute shooting session.

First thing that popped into my mind also

I have never been a fan of Remington UMC


Also use more than one target, keep track of the rounds used with each target
IYAOYAS
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35mm_Shooter
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Posted: 1/14/2012 11:38:17 PM
Amazing, when it's a Larue upper, the problem is everything but the rifle. Ricochets off the ground?? .....
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Posted: 1/14/2012 11:42:59 PM
[Last Edit: 1/15/2012 12:00:16 AM by Big-Bore]
Originally Posted By iNeXile556:
55gr is just fine for 1:7, instability is from too slow a twist not too fast. I shoot 40-80gr from my 1:7 without a problem.



I would not say a 55 gr. bullet is "just fine for a 1:7" because all of my 1:7s do not shoot their best with anything less than 69 gr. Even the 1:8s do not like them all that much, preferring the midweights the best. My 1:7s shoot 55 gr. bullets within MOGrapefruit but they certainly do not shoot their best with the lighter bullets. But still you are correct, over stabilized bullets may not be as accurate as heavier bullets but it is under stabilized bullets that will tumble.

As far as ricochets off the ground. Could be. I have seen some pretty queer things happen from ricochets. Look in the last issue, the NV2011-04 match, issue of the Fifty Caliber Shooter's Associations VHP magazine. There is a picture of a bullet shot at a 1000 yard match that landed short, ricocheted off the ground and stuck in the target tip first like an arrow, not penetrating the target and the bullet was not deformed much at all. They cannot nickname the shooter Skip (already taken and retired) but they did suggest calling him "Stick."

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Posted: 1/14/2012 11:43:29 PM

Originally Posted By 35mm_Shooter:
Amazing, when it's a Larue upper, the problem is everything but the rifle. Ricochets off the ground?? .....

The ammo is a paradox. Underpowered enough to strike the ground in front of the target, yet tough enough to not deform before ripping through the target.



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458winmag
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Posted: 1/14/2012 11:56:36 PM
Damn.
These 55 gr's really get long when they key hole!
Derek45
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Posted: 1/15/2012 12:08:22 AM
1:8 and 1:7 shoot 55gr just fine.

What type of muzzle device are you using ?

take a good look at it, and the crown
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Posted: 1/15/2012 12:21:42 AM
It's either the flash hider, or there was a problem with the barrel, or, one of the ammo types in question is undersized. Remove the flash hider, then, one by one, fire a box of each ammo at a separate target. If only one ammo brand shows the problem, bingo. If they all do, it's the barrel.
If none do. Reinstall the F/H, and repeat the test. If they all do it. It's the flash hider. If one does it, it's that ammo.

55gr will shoot fine in any 1/7 twist. It is overly long bullets that have stabilization problems with 1/9-1/12 twist barrels. It's the length and not the weight, but since the heavier bullets are normally longer, weight is associated with the symptom. There are heavier, shorter bullets that stabilize in the slower twist barrels just fine. What you have with a fast twist like 1/7 is over stabilization. Normally this tends to cause a round to self destruct if it's construction is like that of a varmint round.
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Posted: 1/15/2012 1:40:00 AM
Sounds to me you have a very dangerous barrel the needs to be disposed of. Send it to me for proper disposal....

Seriously, though, most likely the problem is bad ammo. From what I've heard, Larue barrels are top-notch and most likely NOT the problem.

Also, could be somebody else hitting your target at the range.

Next time you go to the range, test the differenct ammo on different targets. And try to pick a lane away from other shooters.

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Posted: 1/15/2012 10:09:23 AM

Originally Posted By h2oskier:
Originally Posted By Dano523:
Double check the FS being loose, with possibly a loose FS that was causing bullet strikes to the FS, with and end result of a few tumbled rounds.

Short of that, funky ammo with some of the bullets a tad cross width under sized, barrel fouled with too much copper to cause the problem, or 5 stray rounds from another shooter.


So on that note, double check the FS to make sure it tight, has no bullet strike, and even check the amount of copper that you are pulling from the barrel rifling when using something like sweets bore solvent to see if the build up is abnormal for only 150 rounds (us did clean the barrel fully before shooting, correct?).


I did not clean my new barrel before shooting.....Is that a problem?

It may or may not be causing the bullet tumbling but a new barrel/rifle should always be thoroughly cleaned before shooting. I'm not sure about Larue but most manufacturers use some sort of coating to protect the components from rusting while being stored and/or shipped and that will need to be cleaned out/off or it could cause you problems.
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iNeXile556
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Posted: 1/15/2012 10:31:34 AM
[Last Edit: 1/15/2012 10:33:25 AM by iNeXile556]

Originally Posted By Big-Bore:
Originally Posted By iNeXile556:
55gr is just fine for 1:7, instability is from too slow a twist not too fast. I shoot 40-80gr from my 1:7 without a problem.



I would not say a 55 gr. bullet is "just fine for a 1:7" because all of my 1:7s do not shoot their best with anything less than 69 gr. Even the 1:8s do not like them all that much, preferring the midweights the best. My 1:7s shoot 55 gr. bullets within MOGrapefruit but they certainly do not shoot their best with the lighter bullets. But still you are correct, over stabilized bullets may not be as accurate as heavier bullets but it is under stabilized bullets that will tumble.

As far as ricochets off the ground. Could be. I have seen some pretty queer things happen from ricochets. Look in the last issue, the NV2011-04 match, issue of the Fifty Caliber Shooter's Associations VHP magazine. There is a picture of a bullet shot at a 1000 yard match that landed short, ricocheted off the ground and stuck in the target tip first like an arrow, not penetrating the target and the bullet was not deformed much at all. They cannot nickname the shooter Skip (already taken and retired) but they did suggest calling him "Stick."


Skip!


I agree about the light rounds not being optimum in the faster twist, but it will still stabilize and as you agreed, not keyhole.
I have had keyholes from ricochets on numerous occasions. I've even did the ricochet shots for fun, (my own range, no danger) try for 10 ring off the ground!. They can and do keyhole.

You can damn near aim ricochets off water.
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Posted: 1/16/2012 11:09:54 AM
Originally Posted By pavlovwolf:
It's either the flash hider, or there was a problem with the barrel, or, one of the ammo types in question is undersized. Remove the flash hider, then, one by one, fire a box of each ammo at a separate target. If only one ammo brand shows the problem, bingo. If they all do, it's the barrel.
If none do. Reinstall the F/H, and repeat the test. If they all do it. It's the flash hider. If one does it, it's that ammo.

55gr will shoot fine in any 1/7 twist. It is overly long bullets that have stabilization problems with 1/9-1/12 twist barrels. It's the length and not the weight, but since the heavier bullets are normally longer, weight is associated with the symptom. There are heavier, shorter bullets that stabilize in the slower twist barrels just fine. What you have with a fast twist like 1/7 is over stabilization. Normally this tends to cause a round to self destruct if it's construction is like that of a varmint round.



+1
I've never encountered a 1-7 that would not shoot 55gr OK. I do get key holing from longer (heavier) bullets in my 1-9 barrels.
Aimless
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Posted: 1/16/2012 12:00:35 PM
I've never seen 55gr come out of my 1/7 sideways Someone was cross firing on that range or something weird is going on with that ammo.
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Posted: 1/16/2012 12:08:08 PM
My money is on the ammo; try it again with some more "quality" ammo, like Hornady for example; see what happens.
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