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AR accuracy issue??

pizzamanny

Sergeant
Full Member
Minuteman
Dec 9, 2011
281
3
47
sc,spartanburg
I just put a new optic and mount on my AR hoping to shoot precision with it.I have not shot this ar much. At 100 yards it will put 2 rounds in one inch and then the next will go 5 inches away. I am using winchester white box. Scope and mount seem to be properly mounted and torqued. Is this normal? where would you start looking for the problem? I was shooting my 308 also and had no problem making accurate and repeatable hits so I do not think it was me.
 
What kind of optic
What kind of mount
What kind or rifle
Prone? From a bench with rest? Offhand?

Winchester White Box is not 'precision' ammunition by any sense of the word. I'd start by trying some match ammo...
 
I'd check the fluid levels in the flux capacitor, if that checks out ok I'd measure the angle in your dangle. Two starting points
 
Fundamentals...

1) Ensure that the Larue mount's throw levers are properly secured to your ARs picatinny rail per ML's instructions for same;

2) Ensure that your ring cap screws are properly secured/torqued down;

3) Ensure that nothing is making contact with your rifle's barrel whether it be the handguard, accessory rails if you have any mounted, benchrest, bags, etc. (also...you just said the rifle is a "DPMS AR-1518inch barrel" but made no mention of its configuration such as free-floated barrel or not, what trigger, whether its factory or a basement/garage build, etc., etc., etc. Any number of different things can cause fliers like what you are getting from the butt of the rifle to the muzzle.)

4) Change to an ammo that is capable of consistent, repeatable results for accuracy testing purposes because WWB, while its ok for plinking, is pretty worthless for determining a rifle's true potential or otherwise for troubleshooting whether the ammo or the rifle itself is causing/contributing to wild fliers.

5) Blame the carpenter...not the tools! ;) Joking aside...shooting your average semi-auto is NOT like shooting a bolt action or other rifle. Shooting one rifle fine (you didn't say if your .308 you mentioned shooting ok was a bolt or a semi) does not mean you'll shoot another in the same way. Any lapse in fundamentals can cause your accuracy potential to go south in a hurry whether its from poor trigger control/manipulation, slopping follow-through, poor or inconsistent position on the rifle/optic, etc., etc. If you confirm all the other items above like ring/mount torque, etc., to swapping to a decent ammo, and your results are basically unchanged...try letting a proven shooter with an AR have a run at it and see if the outcome is any different.

Good luck in getting to the source of the problem. If you do find it and get it resolved, let us know.
 
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I had a similar problem with my DPMS....my first issue was the scope(cheap) and once I got that fixed it was combination of my abilities and the ammo. having only shot bolt guns growing up, I had to change my shooting habits to get consistent results. And on top of that those results rely heavily on ammo. Try a slightly heavier bullet like a 62gr and get a couple of different brands of 55gr. See what the rifle likes but take your time. When I had first started shooting my LR308, I would have sworn it was the rig....turns out it was mostly me because fundamentals between semi's and bolt guns are different.
 
5 moa with winchester white box... that sounds about right. If your trying to shoot for accuracy, you should try some match ammo. There are alot of different brands out there, but bulk white box ammo is not the best for shooting groups. Its like using Mil-Surp ammo, it wasn't made for that.

But once you get all of the other stuff posted above fixed, go back and try again. While you may take an MOA or two off, don't expect amazing results with white box ammo.
 
you need to start reloading if you aren't already. My AR build (1 in 8 twist) wouldn't shoot under 4 moa with any of the cheap ammo out there, including so called NATO 5.56. Started reloading, settled on a 75 gr OTM from Hornady at 2500 fps and my groups went under 1" all the time and I'm no marksman. Each rifle likes it's own weight and velocity, it's up to you to find out what it is.
 
I have a Colt LE6920 M4 that shoots about MOA at 100 yds. I am spoiled because of the super accurate bolt and DCM gun.

After the holidays I'm going to order a Bushmaster DCM barrel with their DCM float tube, gas tube and forearm to install on my LE6920 M$. It should shoot extremely well and still look like a regular thin barrel even though it will be 1" in diameter under the hand guard.

http://www.bushmaster.com/electronic-documents/2005CatalogV2/DCM Rifles & Competition Parts.pdf
 
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That Winchester ammo is crap. That's probably 2/3 of your problem. Get some quality match ammo (RE: Black Hills 69-grain SMK) and start handloading.

Another issue I have seen from working on several of my friends' and co-workers' DPMS rifles/uppers is that they seem to not always have the barrel torqued down correctly. If the suggestions found in this thread don't fix your issue, I would start looking and barrel nut torque. I have seen no fewer than 5 DPMS uppers out of spec ... and two of them could have the barrel unscrewed easily by hand.