AR 10 issues

[jakhamr81]

I've been having some issues with my AR10. I can't seem to get consistent groups under 2 moa. I noticed today that my first rounds of most groups shot are about an inch high. I was wondering if this could have anything to do with the way the first round is chambered? I am using the charging handle to chamber, and when it runs dry I use the bolt release. I should mention that it is an Armalite .308 with free floating Noveske barrel shooting 175 SMKs.

I am open to any other possibilities.- Thanks

 

[DavidAR10]

Re: AR 10 issues


What scope and has it been verified on another rifle?

If yes:
1) 168gr FGMM
2) 175gr FGmm
3) 175gr Corbon Match
4) 150gr Hornady SST Custom Classic

If that don't work:
1) You have a picky barrel and I'd toss it
2) It has always been you.

 

[ORD]

Re: AR 10 issues

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DavidAR10</div><div class="ubbcode-body">
What scope and has it been verified on another rifle?

If yes:
1) 168gr FGMM
2) 175gr FGmm
3) 175gr Corbon Match
4) 150gr Hornady SST Custom Classic

If that don't work:
1) You have a picky barrel and I'd toss it
2) It has always been you.

</div></div>

In addition to the above...try:

1) ensure that your rings/mounts/etc. are all properly torqued down/mounted/etc.

2) try single feeding/skipping the mag and see if that improves anything (could be that your rounds are getting beat up in the mag, upon chambering, etc. and causing accuracy issues).

Also, how are you shooting the rifle (prone, bench from bipod/bags/etc.)? How much time do you have on the trigger of a semi-auto (no offense to you...its just that shooting an AR-10 isn't like your average bolt gun, etc. and it can be a challenging transition)? Let someone else shoot it before you go tossing the barrel!

 

[jakhamr81]

Re: AR 10 issues

I have a Nightforce F1. I have not checked it on another rifle for some time but will give that a try next time at the range. I'm pretty sure it's not me, I shot my 5.56 and was holding .5 moa, however, it is possible that I am changing my position after the first shot and not noticing. I was thinking about picking up a box of Gold Match just to make see the gun shoot. I may also try loading one round at a time.

 

[jakhamr81]

Re: AR 10 issues

Scope/ mount was the first thing I checked. I've got more time on a gas gun than a bolt (about 15 years). I am however new to a .308 AR. That's why I was thinking I may have an effed up position that I am unknowingly adjusting. I am shooting mostly prone with bi pods and rear bag, trying to get straight behind the gun.

 

[BCP]

Re: AR 10 issues

Could be you, could be that when it's cold it throws the first shot high (I have a 223 AR that does that).

 

[Mo_Zam_Beek]

Re: AR 10 issues

Who built the weapon?

Has the barrel nut torque been checked?

Do you have a decent trigger?

Are you sure you are perfectly centered behind the optic at the moment that each shot breaks?


Good luck

 

[zunrj5]

Re: AR 10 issues

Try doing some dry firing and pay close attention to the reticle when you break the shot. If you see it jump try changing how much you are weighting the bipod. You should find a weight/pressure that gets rid of the hop in the reticle and hopefully some of that vertical spread out on the range. Gas guns are much more unforgiving than bolt guns. Remember consistency is key. I hope this helps.

-John

 

[cuffm4615]

Re: AR 10 issues

jakhamr what powder are you using? I was getting pretty shitty results with my LR308 until I started using Varget. The groups got much better but in my opinion they were nothing to write home about when compared to my bolt guns. I also switched my trigger to a Geissele DMR which was like a dream come true. Anyways, I was never fully satisfied with the factory barrel so the rifle is now being converted to a 260 rem with a Krieger bbl., but thats besides the point.

 

[madcratebuilder]

Re: AR 10 issues

Have you tried using commercial 165 match grade ammo?

I have a 21" Noveske barrel on a ArmaLite lower, a ArmaLite two stage I tuned. With DAG surplus it's a sub 2 moa rifle at 100 & 200 yds. With commercial match I'm able to get .7-8 moa, the shooters limit.

Check barrel nut, check head space. Can you inspect the barrel and chamber? Is the crown damaged? A Noveske barrel should be a tack driver.

I've found the .308 AR platform rifles to be the easiest rifles to shoot I have ever handled.

 

[Lowlight]

Re: AR 10 issues

A 5.56 is NOT a 308 and just because you can shoot a 5.56 around .5 doesn't mean you can do the same with a 308... different animal, like the difference between a dog attacking you and a Bear.

 

[dumbbell]

Re: AR 10 issues

OP. Do yourself a huge favor and subscribe to the online training. I used to have the same issue with my ar-10, and if i knew then what i know now, i wouldnt have sold the gun and would have saved a ton in wasted ammo. The online training is priceless if you want to know how to drive ur semi 308 correctly.

 

[benchmstr]

Re: AR 10 issues

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">A 5.56 is NOT a 308 and just because you can shoot a 5.56 around .5 doesn't mean you can do the same with a 308... different animal, <span style="font-weight: bold">like the difference between a dog attacking you and a Bear</span>. </div></div>
what if you are really short and its a large dog? like a labrador? i hear thats the short persons normandy! lol

 

[jakhamr81]

Re: AR 10 issues

I just got done checking the bore, chamber, crown, and headspace. The chamber has a couple reamer marks, nothing too serious. The crown is good. There's a few signs of fire cracking, and the chamber checked out a bit on the tight side bit within spec. I ordered some Federal 168s, they've always performed well in everything I've shot them in.

There was quite a bit of carbon build up in the rifling as I was shooting almost always suppressed. I got all the carbon removed and I will hopefully get out this weekend or early next week to try again.

We shall see.

 

[Awesymoto]

Re: AR 10 issues

Is your rifle brand new? I had issues in my DPMS for the first few hundred or so rounds, No idea why but it took a while to settle down. Possibly the parts needed to mate together, like piston rings in an engine? No idea, not a machinist, metallurgist, etc.
Now it drives good groups with relative ease. It was either A. like i mentioned above the rifle took a minute to settle, or B. I took a minute to adjust to it.

I also have had "mystery" problems, then tightened my rings up a hair, and they went away....

 

[rchman]

Re: AR 10 issues

"Driving" a 308 AR is tough. I had trouble getting consistently good groups with mine (often 1.5 MOA-2MOA). My brother would get behind it and ring out 3/4 MOA.

Meanwhile, I can consistently get 3/4-1 MOA with my AR15 and match ammo.

 

[toadbrown]

Re: AR 10 issues

Good info guys!

 

[jakhamr81]

Re: AR 10 issues

I had a chance to shoot it this weekend and I am glad to say that I am averaging right around or just under 1 MOA again. I shot about 40 rounds of my 175 SMKs and had groups as tight as .60 and the largest being 1.12.

I believe the main culprit was the carbon build up in the barrel. It was pretty stubborn, carbon solvents weren't touching it. I pulled out several clean patches so I thought the bore was clean. I brought the gun to my armorer who checked the head space, throat, and bore. He had to use JB compound, and after a few patches of that he could not see any more carbon in the groves.

I will have to pick up some JB with my next Brownells order.