DPMS ar-15

by Guncrazy21 on Sun Dec 25, 2011 2:01 am

I have a dpms ar-15 .223 and have been having trouble sighting it in. I use an eotech with a 7x magnifier and the barrel has a 1x9 " twist. I usually use American eagle FMJ ammunition (just to save on money) but I absolutely can not make it shoot any less than a 5 " group , from as close as 40 yards all the way out to 150. I am pretty sure the eotech is accurate, but I dunno what else it could be. Maybe the ammo or does anyone know anything about dpms barrel quality?

by MrClean on Sun Dec 25, 2011 7:51 am

First I would check the mount point(s). Make sure nothing got up under there when the EOTech was being installed that is preventing a solid lockdown. Do you have iron sights coexisting? If so, I would shoot using them to rule out any issue with the EOTech. I've never had any issues w/ my EOTech's but do have a friend that had one keep going off zero. But never heard of one just shifting enough to cause large groups.

Did it ever group tight? Maybe prior to installing EOTech? Or is this first shooting? Was it a new rifle or used? How many rounds down it if used?

Now to my first thought. It's a DPMS. I am in no way meaning that to be a bash. But I don't even order them anymore for customers. I had enough of their hit/miss quality over the years and their customer service department. The final straw was a SASS rifle that we ordered and waited over TWICE the promised delivery time for. When finally arrived.... guess what.... customer (whom I KNOW is an excellent shot) couldn't get any better than a 4" group at 100yards was just slightly irritated.

But I have seen many many DPMS rifles that were reliable and very accurate as well. I would first start by removing and mounting again, being sure nothing is in the mount area that could be giving you a "shifty" mounting. Then shooting with iron sights. Surely someone will let ya borrow a rear BUIS if you have the front sight post. If you are still having same results with iron sight it must be the bbl. If used, check bore to see if it is horribly fouled or otherwise damaged. Possibly a new bbl is in order. Sad

by miker84 on Sun Dec 25, 2011 9:27 am

Yeah, it oughta do better than that. I'm with MrClean on checking the optic mounts.
Pics of gun?

by jakeg823 on Sun Dec 25, 2011 9:40 am

I have the same issue with my DPMS oracle. Both with BUIS and my Trijicon reflex. As far as reliability is concerned it can't be beat. But 5" groups at 50yds is the norm for me as well. Might do a barrel swap at some point myself when I have the extra cash to blow on one

by Stumpbud on Sun Dec 25, 2011 10:00 am

Man! That is bad luck, I don't what I would do if I any gun that only shoot a 5" group. I hope you can get something figured out. I would hate to even sell a gun like that to any one I know.

by miker84 on Sun Dec 25, 2011 10:02 am

Have y'all tried 62gr to see if it does better?

by 308th_sps on Sun Dec 25, 2011 9:01 pm

Also have someone re-torque the barrel nut.

308th_sps

by jakeg823 on Sun Dec 25, 2011 9:01 pm

miker84 wrote:Have y'all tried 62gr to see if it does better?

I haven't. Hard enough time finding 55gr for a reasonable price. I don't think I've ever seen factory 62gr on a shelf(outside of that remington corlokt bull

) and I'm not to the point of reloading .223/5.56 yet

by crazyace85 on Sun Dec 25, 2011 11:33 pm

My dpms is doing about 5" groups at 25yards and has keyholing. Lol. Thousands of rounds and recent slidefire action is the cause for me. Not sure of your circumstance but maybe that helps. Keep in mind most commercial ARs do not have chrome lined barrels and thus barrel life is shorter and they won't hold up to full auto as well. Chrome-moly isn't chrome lined as a lot of folks misunderstand.

by beltfed on Mon Dec 26, 2011 12:59 am

Heres my thoughts. A 5" group @ 40 yds is not going to be caused by bad ammo, improper barrel twist, poor shooter capability or a bad muzzle crown. Those are all things that open up groups maybe a couple inches at 100 yards.......maybe.

Your problem is, in my opinion, parallax, parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight.

In my opinion your problem most likely lies here:

with a 7x magnifier

Please forgive me if I am wrong but based on your lack of info regarding the magnifier I would assume you are using non EOTech magnifier.

The cheaper made magnifiers are not parallax free, or fixed at a given distance either. If your magnifier is not guaranted parallax free at 40 yards your aiming dot will wander on the target and change the barrels point of aim regardless of how well you center the dot on the bull.

4" of dot travel may not even be noticeable at 40 yards to the naked eye so before you knock my theory I would suggest finding a good quality scope with adjustable parallax, side adjust or objective lens adjustable is fine, so long as it is adjusted properley. A good Nikon or Leupold will probably yield the accuracy your rifle is most likey capable of even with cheap ammo.

Most people confuse the parallax adjustments with the "focus" adjustment knobs on rifle scopes. Fixed magnifiers do not have a parallax adjustment. they are usually parallax free. The reason a name brand magnifier costs $500 and a cheap one costs $100 is the expensive ones are made to be parallax free, or at least parallax free after 25 yards in most cases.

Its an inevitable result of magnifying an image and it takes a good quality optic to eliminate parallax.

Thats just my opinion, take it with a grain of salt......and maybe some pepper to spice it up. Good luck in your findings.

by kaferhaus on Tue Jan 17, 2012 2:36 pm

+2 on the re-torque of the barrel nut. I've "fixed' several ARs that way

DPMS ar-15

DPMS ar-15

Re: DPMS ar-15

Re: DPMS ar-15

Re: DPMS ar-15

Re: DPMS ar-15

Re: DPMS ar-15

Re: DPMS ar-15

Re: DPMS ar-15

Re: DPMS ar-15

Re: DPMS ar-15

Re: DPMS ar-15