About to give up on my large frame AR

[LVLAaron]

Previous struggles shared here: http://forum.accurateshooter.com/threads/trouble-with-a-newly-build-308-ar10.3940473/

Short version – 2 inches groups regardless of load. Tried 12 loads in .3g increments, every load looked the same. Ugly. Replaced the barrel with a Faxon match barrel and adjustable gas block.

Broke in new barrel with Black hills ammo (and gas block completely closed) had some pretty good single/bug hole groups. Was happy.


Went shoot again for load dev, not a lot of luck. This time the gas port was open so the gun would cycle and lock open. (no pictures of this trip)


Using Sierra bullets and data. Sierra says their accuracy load for the 168g HPBT was 42 grains of RE-15 so I used that as my middle load.

Plan was to shoot 5 groups with the port open and 5 with the port closed.

Loads:
41.0
41.5
42.0 (Sierra pet load)
42.5
43.0


Results. (second group on the bottom row is 4 shots, had a dud primer (first out of thousands of CCI-BR2!))

https://imgur.com/EQtscWN


I’m not sure what else I can do, if this is what I should expect for a gas gun, etc. I’m about to sell it and just get a Tikka t3x CTR

 

[Ledd Slinger]

Gonna be hard to sell it after posting that data all over the Internet. Have you contacted the barrel manufacturer?

My best friend bought a Noreen Arms Long Range Assassin in 300 win mag. I couldn't get it to shoot under 1.5" group for him with any handloads. Most groups were around 2". Found one box of factory ammo where it shot a 1" group. Best it ever did, then wouldnt do it again. He eventually called Noreen Arms and described the issue. They told him to send it in so he did. They tested it more themselves and ended up replacing the barrel for free. It shoots much bether now.

 

[people]

When the gas off it shot good you say. Does it shoot the factory stuff good with the gas on? How does it shoot the hand loads with the gas off.

I would try different primers. I know you do not want to try different primers or brass but I would look into different primers. Some rifles just do not like some components.

Your brass should be good to go. But it would not hurt to try something else.

On my AR-10 I needed to add weight to the carrier to tame it down. I had a tubb carrier weight system so I stuck in the heaviest one and it helped.

 

[B Nettesheim]

I havent read through everything but have you tried Varget, 4320, 4064 or the newer alliant stuff in that range? Try Winchester primers maybe. Dont give up yet.

 

[Mastershot]

Check your seating depths, neck tension and runout.

 

[Sniper338]

I read the first paragraph of your original post and have no clue who or what those manufacturers are besides aero precision. Are they all low end cheap stuff? is it a budget build?

I have several aero precision uppers/lowers, I know thats not the problem.

 

[spencerhenry]

My ar10 loves 168gr sierras and imr4895.

 

[DirtySteve]

Ok, I don't want to sound mean or anything like that but... I doubt you will get that barrel to shoot much better. I had not heard of the first barrel you used I have heard of Faxon but never known anyone to use one. I checked and at the price they are selling them I doubt they are true match grade barrels. I checked and Midway has Shilen barrels for AR10's and they are a very reputable barrel maker. That would be my recommendation.

 

[Depart123]

You are finding out through experience why there are so comparatively few people on here touting the accuracy of thier semi-autos, especially the big ones.

They suck, plain and simple.

I don't mean that accurate ones don't exist, because they do. You just have to pay through the nose for them. Occasionally a unicorn pops up, it happens. I'm sure someone will chime in shortly about their AR10 that shoots bug holes...blah...blah....blah.

Reality is that 2moa for a big semi is pretty standard. If it does better than that....then you won.

 

[Rodney]

Would try a different powder like 308sawyer said. I’ve got a rifle that is finicky when it comes to the powder selection. Once I found the powder it liked, was like a whole different gun. I mean groups went from 1.25” to .5” at 100 yards. Couldn’t believe the difference it made. Good luck and don’t give up, you’ll crack the code for that thing. Don’t forget benchmark, I’ve had good luck in my ar-15 with it, and it will work for 308 to.

 

[LVLAaron]

Gonna be hard to sell it after posting that data all over the Internet. Have you contacted the barrel manufacturer?

My best friend bought a Noreen Arms Long Range Assassin in 300 win mag. I couldn't get it to shoot under 1.5" group for him with any handloads. Most groups were around 2". Found one box of factory ammo where it shot a 1" group. Best it ever did, then wouldnt do it again. He eventually called Noreen Arms and described the issue. They told him to send it in so he did. They tested it more themselves and ended up replacing the barrel for free. It shoots much bether now.

Read through my other thread that I linked to. Had a ton of trouble with one barrel, got a different one. This one is less troublesome, but I'm starting to think it's something else. I've been through all kinds of loads and combinations, etc.

 

[LVLAaron]

I havent read through everything but have you tried Varget, 4320, 4064 or the newer alliant stuff in that range? Try Winchester primers maybe. Dont give up yet.

With the original barrel I went through Hornady and Peterson brass, 8208, Varget, Black Hills factory stuff, IMR4166 and probably something else...

 

[LVLAaron]

I read the first paragraph of your original post and have no clue who or what those manufacturers are besides aero precision. Are they all low end cheap stuff? is it a budget build?

I have several aero precision uppers/lowers, I know thats not the problem.

Not budget. The barrels aren't 5-600 dollars but Ballistic Advantage OEM's barrels for a lot of people, their stuff is supposed to be great, has a 1moa guarantee. Faxon is newer and I've seen lots of AR15 guys shoot bug holes so I thought I'd give it a try.

 

[spencerhenry]

You are finding out through experience why there are so comparatively few people on here touting the accuracy of thier semi-autos, especially the big ones.

They suck, plain and simple.

I don't mean that accurate ones don't exist, because they do. You just have to pay through the nose for them. Occasionally a unicorn pops up, it happens. I'm sure someone will chime in shortly about their AR10 that shoots bug holes...blah...blah....blah.

Reality is that 2moa for a big semi is pretty standard. If it does better than that....then you won.

My armalite ar10t shoots one ragged hole with 125gr tnt and 168gr sierra. Guess I got lucky?

 

[LVLAaron]

Would try a different powder like 308sawyer said. I’ve got a rifle that is finicky when it comes to the powder selection. Once I found the powder it liked, was like a whole different gun. I mean groups went from 1.25” to .5” at 100 yards. Couldn’t believe the difference it made. Good luck and don’t give up, you’ll crack the code for that thing. Don’t forget benchmark, I’ve had good luck in my ar-15 with it, and it will work for 308 to.

I have sierra 175's and 8208/Varget on hand I can try and run through it this weekend

 

[Delfuego]

On my AR-10 I needed to add weight to the carrier to tame it down. I had a tubb carrier weight system so I stuck in the heaviest one and it helped.

Same here.

The Tubb CWS helped with overgassing and helped the brass from getting chewed up. I dont think he sells them, but it might be worth a call to him. JP sell heavier bolt carriers and tune-able buffer systems. I would immediately check to see if the bolt headspaces properly to the barrel. Bolt, barrel and barrel fit into the upper make up most of the accuracy in an ar. Maybe the upper receiver is out of spec? Loose fitting barrel? I never heard of that bolt/bcg, might want try get another bolt.

I feel you pain on this, ar stuff is supposed to be plug and play, but it never is. Large frame ar is even worse. I think going forward I would only buy a complete from a good company (JP/Seekins) or from a select few builders like (Compass Lake). Good luck!

 

[Sniper338]

Not budget. The barrels aren't 5-600 dollars but Ballistic Advantage OEM's barrels for a lot of people, their stuff is supposed to be great, has a 1moa guarantee. Faxon is newer and I've seen lots of AR15 guys shoot bug holes so I thought I'd give it a try.

oh ok. I honestly didnt know.

 

[gravelyctry]

Have you actually verified the barrel twist? Actually measure it rather than rely on what the manufacturer put on the outside of the barrel?

 

[Depart123]

Previous struggles shared here: http://forum.accurateshooter.com/threads/trouble-with-a-newly-build-308-ar10.3940473/

Short version – 2 inches groups regardless of load. Tried 12 loads in .3g increments, every load looked the same. Ugly. Replaced the barrel with a Faxon match barrel and adjustable gas block.

Broke in new barrel with Black hills ammo (and gas block completely closed) had some pretty good single/bug hole groups. Was happy.


Went shoot again for load dev, not a lot of luck. This time the gas port was open so the gun would cycle and lock open. (no pictures of this trip)


Using Sierra bullets and data. Sierra says their accuracy load for the 168g HPBT was 42 grains of RE-15 so I used that as my middle load.

Plan was to shoot 5 groups with the port open and 5 with the port closed.

Loads:
41.0
41.5
42.0 (Sierra pet load)
42.5
43.0


Results. (second group on the bottom row is 4 shots, had a dud primer (first out of thousands of CCI-BR2!))

https://imgur.com/EQtscWN


I’m not sure what else I can do, if this is what I should expect for a gas gun, etc. I’m about to sell it and just get a Tikka t3x CTR

The fact that it shoots fairly well when the gas is off shows that it is not the load.

Try one more thing. Someone mentioned this in the earlier thread, load rounds from the magazine one at a time. So put a round in the magazine, lock the bolt back, insert magazine, and let the bolt go home from pressing the bolt release. Fire the round letting the bolt lock back and repeat.

What this will do is make sure every round is loaded from the magazine and the bolt will lock up with no bolt drag from rounds pushing up from the magazine. If the groups tighten up, then you know bolt drag from the magazine is preventing consistent bolt lock up.

I use 10 round magazines in my precision AR's for this reason. I usually put just 5 rounds at a time in them. When single loaded in the manner described above, this gun shoots under 3/4 MOA consistently. When I use a 20 or 30 round magazine the very same loads will open up to 1 3/4 MOA.

 

[NickB1075]

I think you have been given some great info to start with. I have used two Faxon barrels in my ar15, as well as a few friends and we all came to the conclusion they are OK barrels. I went back to my WOA and will not look back ever again for the ar15. Some shot better then others but none were one hole shooters. That's just my experience with them.

On that note before throwing in the towel I would try some "good old" powders that the service rifle shooters often used in the m1a and Garands. For example 4895, or my personal favorite IMR 4064. Loading for gas guns is a different ball game in my opinion.

It has been a while since I shot service rifle but for the 308 r15 was not often a go to powder for the gas guns.

Nick