Barrel length on AR-10

[Kenneth66]

My nephew has a DPMS AR-10 with a 16" barrel . We have tried several brands of hunting and match ammo in it . It has a pro staff five 4-18 sf for glass .
Shooting at 100 yds it just will not group . He bought the rifle new , we tried griding the scope on targets to eliminate canting . Trigger is a a beast but I have shot worse . He and I both have gave it a good workout . Three inch groups was the best we could get out of it some were as much as five inch groups . This rifle should do better than this I would think . Would it be the short barrel ? It is chambered for 308 or 7.62x51 .
Thanks , Kenneth

 

[AndyA]

I have a DPMS Oracle in 308 with a 16" barrel and the trigger was the worst. I replaced it with a CMC single stage trigger at 3lb pull and that helped a lot. Also what are you shooting for ammo? PMC is junk and wouldn't group but Federal Gold Medal Match really tightened things up. My reloads are even better.

 

[mac86951]

I have a DPMS Oracle in 308 with a 16" barrel and the trigger was the worst. I replaced it with a CMC single stage trigger at 3lb pull and that helped a lot. Also what are you shooting for ammo? PMC is junk and wouldn't group but Federal Gold Medal Match really tightened things up. My reloads are even better.

+1; also try glass on another rifle if you suspect it.

Many items could be loose too; free floated barrel?

-Mac

 

[mic2377]

Other issues can at foot in the AR design. Things like a loose barrel nut or out of spec chamber. How does the brass look?

Another factor is 308 AR's are NOT easy to shoot well. Heavy, gritty triggers, a long recoil impulse, and uncomfortable stocks all add up.

I don't think it is related to barrel length - I have shot many 16" ones that are accurate as their longer-barreled cousins.

I would try and feed it some 168 gr Fed Gold Medal Match and go from there. If that doesn't work more work may be in order.

 

[Kurz]

Three inch groups was the best we could get out of it some were as much as five inch groups .

Trying to diagnose rifle failures online is like hunting and pecking on a keyboard. There are simply too many variables to attempt to solve a problem in a short post. However...

Check your scope first. It is not impossible that Nikon shipped a goof and you wound up with it. I'm not disparaging Nikon by any means but every manufacturer makes one mistake every now and then.

I suppose for the $20.00 investment that you could try the GMMC next since anything more will involve work. But I have my doubts that it will cure 3" groups. But I've been wrong before.

Personally, I would suspect the DPMS barrel and assembly. No matter what DPMS claims, their 'precision manufactured barrels' aren't. These assemblies, like those built in most other plants are put together by unskilled labor who have been trained in place to do assembly line work. And like any other assembly line, there is a chance for a failure of parts that aren't tightened properly or need some other attention due to alignment.

But the solution requires detective work and some better than average knowledge of the function of the LR-308. If you don't have this ability then I suggest that you find a gunsmith that does and let him go through the rifle thoroughly. AR-type rifles have a unique set of potential problems when compared to bolt action rifles, there are a bunch of moving parts that need to be in agreement and alignment with each other. Misalignment, over-gassed, under-gassed, gummy parts, loose barrel nut, on and on.

If you opt for a gunsmith to handle this, you may want to consider letting him do a tiny touch of trigger work. There isn't much he can do with the fixed relation of the parts so be prepared for the possibility of having to buy a new trigger to solve that problem.

Good Luck with the search!

 

[savagedasher]

Put a RAS Tuner brake on it along with the wege between the receiver . Larry

 

[ronsatspokane]

Trying to diagnose rifle failures online is like hunting and pecking on a keyboard. There are simply too many variables to attempt to solve a problem in a short post. However...

Check your scope first. It is not impossible that Nikon shipped a goof and you wound up with it. I'm not disparaging Nikon by any means but every manufacturer makes one mistake every now and then.

I suppose for the $20.00 investment that you could try the GMMC next since anything more will involve work. But I have my doubts that it will cure 3" groups. But I've been wrong before.

Personally, I would suspect the DPMS barrel and assembly. No matter what DPMS claims, their 'precision manufactured barrels' aren't. These assemblies, like those built in most other plants are put together by unskilled labor who have been trained in place to do assembly line work. And like any other assembly line, there is a chance for a failure of parts that aren't tightened properly or need some other attention due to alignment.

But the solution requires detective work and some better than average knowledge of the function of the LR-308. If you don't have this ability then I suggest that you find a gunsmith that does and let him go through the rifle thoroughly. AR-type rifles have a unique set of potential problems when compared to bolt action rifles, there are a bunch of moving parts that need to be in agreement and alignment with each other. Misalignment, over-gassed, under-gassed, gummy parts, loose barrel nut, on and on.

If you opt for a gunsmith to handle this, you may want to consider letting him do a tiny touch of trigger work. There isn't much he can do with the fixed relation of the parts so be prepared for the possibility of having to buy a new trigger to solve that problem.

Good Luck with the search!

Good suggestions but I have to disagree about their barrels. Having scoped a few fresh factory barrels (and a lot of not so fresh), one of the best I've ever seen is the 24 inch barrel on the first gen LR-308 I've got in trade from my brother-in-law. I expect to see some tooling marks all barrels, even those "select match" barrels but that thing was as smooth as a baby's butt. Shoots pretty good as well. I'd call it 3/4 MOA with my loads which did not require a lot of load development. Having said that, I've seen some ugly barrels that shoot lights out. Never have air gauged barrels though and that could be the deciding factor.

P.S. The trigger on my DPMS was one of the worst I've had. More than a mile of creep and gritty to boot. 20 minute trigger swap with a $70 ALG and good to go. Cheap trigger but very good for the money.

 

[Kurz]

Good suggestions but I have to disagree about their barrels. Having scoped a few fresh factory barrels (and a lot of not so fresh), one of the best I've ever seen is the 24 inch barrel on the first gen LR-308 I've got in trade from my brother-in-law. I expect to see some tooling marks all barrels, even those "select match" barrels but that thing was as smooth as a baby's butt. Shoots pretty good as well. I'd call it 3/4 MOA with my loads which did not require a lot of load development. Having said that, I've seen some ugly barrels that shoot lights out. Never have air gauged barrels though and that could be the deciding factor.

P.S. The trigger on my DPMS was one of the worst I've had. More than a mile of creep and gritty to boot. 20 minute trigger swap with a $70 ALG and good to go. Cheap trigger but very good for the money.

I will always agree with most of the stock AR's needing a trigger upgrade. Many are supplied with the very cheapest of parts which are not worth the effort to stone even a little. It's better to buy an upgrade and appreciate your intelligence for making that decision.

Barrels, like some other components, can run the gamut from excellent down through just plain awful. Of course there will always be exceptions (as you mention) but that's not the gist of most reports since we're essentially looking for the broad cross section not the diamond in the rough. Maybe I was being a little harsh... Less expensive AR's use less expensive components so they can maximize the profit. Sure you can find a good one every now and then but the general consensus is for a less than stellar but acceptable review. The kicker is what level of acceptance we are willing to take for our uses. Not everyone needs the absolute best barrel. That's why the middle of the road market exists and flourishes.

Personally I would settle for 3/4 MOA on a stock AR for general purpose shooting. My competition AR's need to perform at a higher level. After building dozens of bolt action rifles for PRS competitions, I decided to build a killer AR10 clone mostly because of the mover stage. The 6.5 Creedmoor allowed me to shoot more than adequately at the steel stages but it really shined on those movers! I was finished and off station far faster than the bolt guys and with a 100% hit count.

I think that one of the real bugaboos about AR barrels is the huge selection of unknown or unstated makers of barrels available from dozens of websites for reasonable amounts of money. There are so many that it is nearly impossible to determine which ones might be the better selection. So I settle on making my own from Bartlein blanks.

Good Shooting!

 

[Kenneth66]

Thank all you for your for your responses . I will pass this on to him when Isee him again Monday or advise him to visit the site . We did shoot some good match ammo along with some good hunting ammo . With some we would get two shots with in 3/4"-1" and the flier would open it up to three inches or more. . With the hunting ammo it shot all around . Match ammo consisted of Fiocchi , Black Hills , Federal , and there was another brand I can't recall at the moment . Hunting ammo was a variety of Winchester , Remington , and Federal . So I guess from here it will depend on how much he wants to put into the rifle . Thanks , Kenneth

 

[mic2377]

If he decides on a barrel swap I would consider a Criterion, both myself and friends have had excellent luck with these in 308 AR's. They are not horribly expensive either.

 

[jonbearman]

I have an armalite in .308 and it digests everything with handloads doing the absolute best. I shoot the hornady 168 grain match with ball powder to get under an inch with ease. The 110 vmax for woodchucks works ok and groups around one inch. How are you cleaning your barrel as it sounds like it has quite a few rounds down it now. Some barrels copper up fast especially if shot in rapid fire or no cooling between rounds etc. The factory triggers are too heavy in my opinion so I opted to put a chip mcormick in mine. Thr trigger helped a lot. I have shot match loads at 100 yds in the 3/8ths range. A good rest will help as well.

 

[Txhillbilly]

I have a DPMS LR-260H,and it has always shot excellent. I changed the trigger out with a RRA 2 stage NM trigger before I ever shot it because I know how the factory triggers are on all AR's.
I use this rifle for hunting hogs,so the only bullet it gets fed are the 140 gr Sierra Gameking that I load for it.
With the AR platforms,there are so many things that can affect the accuracy of them. You have to start trouble shooting everything to find out the causes. It can be a real pain at times.