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Started By
Message
Brand new AR build wont hold a pattern
Posted on 3/21/16 at 7:58 am
Posted on 3/21/16 at 7:58 am
Asking for a friend, seriously. A buddy of mine just finished building an AR with sentinel arms barrel and spikes billet upper/lower combo. The rifle feeds reliably but wont shoot a pattern. Bullet strikes are all over the map. We thought we fixed it because the barrel nut had slightly loosened up. Torqued it back down and it shot great, then the problem started again. We retightened the barrel nut, but due to lack of light we were unable to test fire it again. My question is, what in the world could be making the barrel nut loosen up, and/or make this "premium" part rifle shoot like and AK that's been run over by a tank?
7
Posted on 3/21/16 at 8:52 am to 4X4DEMON
What optics do you have on the rifle?
Posted on 3/21/16 at 8:55 am to 4X4DEMON
quote:
this "premium" part rifle
quote:
sentinel arms barrel and spikes billet upper/lower combo
What optic is "he" running?
This post was edited on 3/21/16 at 8:57 am
Posted on 3/21/16 at 8:55 am to Shexter
3x9 leupold rifleman I think.
Posted on 3/21/16 at 8:57 am to 4X4DEMON
What scope mount is he using?
Posted on 3/21/16 at 8:57 am to Carson123987
$200 barrel is premium to me. Sorry I'm not Ballin like some folks
Posted on 3/21/16 at 8:59 am to 4X4DEMON
quote:
$200 barrel is premium to me
Posted on 3/21/16 at 9:03 am to northern
Excuse my ignorance your highness. What should I do with this piece of shite boat anchor?
Posted on 3/21/16 at 9:11 am to 4X4DEMON
quote:
4X4DEMON
We're just pickin on you
Seriously though, what scope mounts is he using? 90% of the time, my customers need their scopes remounted properly or a new mounting setup.
quote:
then the problem started again. We retightened the barrel nut
shouldnt have to be doing this. follow the torque instructions that came with the rail you used.
This post was edited on 3/21/16 at 9:27 am
Posted on 3/21/16 at 9:23 am to 4X4DEMON
Try lubing the BCG a little more than normal. Some rifles like it "wetter" than others.
Posted on 3/21/16 at 9:24 am to 4X4DEMON
How much torque are you putting on the barrel nut? The spec is fairly wide for a reason and it's suggested to be tightened to max spec (with the proper anti-seize lube) then backed off (do this 3-4 times) and re-torqued as far as possible in spec to allow the gas tube to fit. Those combination "armorers" tools are not that good, dedicated 3-pin wrench and a decent sized torque wrench do the proper job with the upper locked in a vice block that secures the barrel extention too.
This post was edited on 3/21/16 at 9:25 am
Posted on 3/21/16 at 9:25 am to 4X4DEMON
I've had a gunsmith, friend's step dad from Fredericksburg, do a demonstration with a shitty rifle that he was hired to 'sight in'. He ran a piece of paper between the stock and barrel while cold, then fired two rounds, then put the paper back in. You could see the gap on the right side decreasing. Fired a couple more shots and he couldn't even slide the paper back between barrel and the stock. fricking thing was just warping as it got hot.
He sighted it in by letting it cool between shots. Job done...gun, TPOS.
He sighted it in by letting it cool between shots. Job done...gun, TPOS.
This post was edited on 3/21/16 at 9:29 am
Posted on 3/21/16 at 9:27 am to doubletap
quote:
Try lubing the BCG a little more than normal. Some rifles like it "wetter" than others.
Posted on 3/21/16 at 9:30 am to 4X4DEMON
quote:
Excuse my ignorance your highness.
Haha. Sorry. Extra salty this morning I guess.
How big of a variance in a pattern are we talking?
Did you shoot with irons and optics?
Are you using a torque wrench for the barrel nut? Id be most worried about the fact it is coming loose.
Posted on 3/21/16 at 9:30 am to 4X4DEMON
quote:
The rifle feeds reliably but wont shoot a pattern. Bullet strikes are all over the map.
Sounds like shooting fundamentals - at first glance.
quote:
We thought we fixed it because the barrel nut had slightly loosened up. Torqued it back down and it shot great, then the problem started again. We retightened the barrel nut, but due to lack of light we were unable to test fire it again.
Threads could be stripped - not likely, because you would probably have noticed with the loosening/tightening.
quote:
My question is, what in the world could be making the barrel nut loosen up, and/or make this "premium" part rifle shoot like and AK that's been run over by a tank?
This is what I would do - drop all the fancy optics and zero the thing (if possible) with iron fricking sights. If 30 to 60 rounds doesn't pattern with iron sights, you have some fundamental problems that I would recommend taking the thing to a professional.
IF you can zero it with iron sights and it doesn't pattern through the glass - it is either the glass, the mount, or a combination of shooter/mount/glass - again, all IMHO.
This post was edited on 3/21/16 at 9:31 am
Posted on 3/21/16 at 9:35 am to 4X4DEMON
quote:
Bullet strikes are all over the map
How far all over the map are we talking about? What distance are you shooting?
A gun not shooting well can be any number of things. You just need to pinpoint what is the issue. First thing is to eliminate the scope. I would bore sight it with iron sights and test fire it at about 25-30 yards. Get tight groups there then move up to 50-100 yards.
If you can't get tight groups at 25 yards you have a bad barrel, bad ammo, or bad shooter.
Posted on 3/21/16 at 9:44 am to Carson123987
I know ya'll just frickin around. It's early and I worked last night, had to be back at 0730. I'm probably just in a shitty mood.
Posted on 3/21/16 at 9:48 am to jdavid1
Only used the glass, as no iron front sight was available at the time. Multiple shooters, from a rest had patterns that would be as much as a foot off the target, but never consistently in the same place. After the first issue, where the barrel nut was retightened, it shot consistent groups. On the next outing it was all over the berm again. Glass used with Leupold rifleman mounted on leupold rings/bases. Those were removed and remounted to ensure proper mount. Barrel was tightened in a vise block with hi-temp anti seize in the fashion of on/off/on/off/on/off/on.
Posted on 3/21/16 at 9:54 am to 4X4DEMON
quote:
Multiple shooters, from a rest had patterns that would be as much as a foot off the target
What distance were you shooting?
quote:
Barrel was tightened in a vise block with hi-temp anti seize in the fashion of on/off/on/off/on/off/on.
With a torque wrench I assume?
This post was edited on 3/21/16 at 9:57 am
Posted on 3/21/16 at 9:57 am to northern
Originally 100yds, the next trip to the range after we worked on it again 50 (shot great) then 100 (shot great), let it sit for a week back to range @ 100 again and it shot like shite
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