Accuracy problem AR10 Faxon Gunner .308 18"

[bltmonty]

Hello members,

I need some help with my Faxon gunner .308 barrel. When I shoot more than two or three shots, it begins drifting right. The following photo shows a string, shot at 80 yards, after I waited 15 minutes for the barrel to completely cool down. I shot the first one in the middle of the duct tape. I waited about 20 seconds and shot the next one to the right. After about 10 seconds, I shot the the 3rd and 4th, and after 10 seconds, I shot the 5th and 6th, all moving right. I get MOA in vertical but, obviously, not horizontal.

I can put on another AR10 upper .308 barrel (a cheap non-name barrel) on the same lower on the same day, same rest, and same loads, and I don't get the stringing problem.

When this first happened, I changed the scope, thinking it was the problem; but the drifting continued with a better scope. I am using 168gr SMK and 168gr Hornady HPBT and Lake City and Lapua brass; I have tried four different powders and even cheap 147 grain bullets. I am not getting pressure signs and loads are below maximum charges. It has an Aero Precision upper and toolcraft BCG.

FWIW, I own ten ARs and other rifles, and reload for 13 different cartridges. and can usually get MOA, even .5 MOA on all my AR pistols and rifles.

I have sent Faxon customer service two emails, and no response. I have a one shot AR barrel.

 

[d2wing]

Could be the barrel. Could be a fault in the assembly or fit of the upper. Could even be a Bolt or BCG problem. Free floated I assume.

 

[CopperClad]

Take it all apart, clean the day light out of it, then reassemble to spec. See it that clears the drift problem.

 

[citizenconn]

What kind of optic are you using? Try it with the optic then try it with iron sights and see if you get the same issue?
I don't often see an AR barrel with problems that shifts in only only plane like that without there being some other causative factor.

 

[BreechFace]

Not sure if the mods will care about this or not, if they don't like it they can clear this post.

Maybe try and post in AR15.com in the Faxon Industry page, and see if you get some response then. Sometimes it takes a polite question asked on a public forum to get a response.
https://www.ar15.com/forums/Industry/Faxon-Firearms/700/

There are Faxon members there that go by "Faxon_ " with the blanks being different names like Pat, Martin, etc.

 

[BreechFace]

I've had good luck so far with one of their barrels, but I've seen my fair share of Faxon issues on forums to think that they don't put out a lemon now and then.

 

[Shawn Dodson]

I've tried two of the 20" Faxon Big Gunner .308 barrels on my AR308 and the accuracy of both were very disappointing. Neither barrel grouped well at all with any loads. Faxon replaced my first barrel under warranty and it was as bad as the first one, so I just gave up with Faxon and bought a Wilson Combat Tactical Hunter fluted barrel and drove-on.

 

[C-grunt]

I second amp-rat's idea. Take it apart and put it back together just to make sure something did come loose or get installed slightly off.

If that doesnt work then we have it narrowed down to the barrel.

 

[redcon1]

Harmonics crown sub- optimal charge weight?

 

[bfoosh006]

Did you happen to lap the upper , prior to the barrel install ?

Is the barrel shimmed in place, or Loctited ?

Nothing in even close contact to the gas block ?

 

[mshootnit]

Hello members,

I need some help with my Faxon gunner .308 barrel. When I shoot more than two or three shots, it begins drifting right. The following photo shows a string, shot at 80 yards, after I waited 15 minutes for the barrel to completely cool down. I shot the first one in the middle of the duct tape. I waited about 20 seconds and shot the next one to the right. After about 10 seconds, I shot the the 3rd and 4th, and after 10 seconds, I shot the 5th and 6th, all moving right. I get MOA in vertical but, obviously, not horizontal.

I can put on another AR10 upper .308 barrel (a cheap non-name barrel) on the same lower on the same day, same rest, and same loads, and I don't get the stringing problem.

When this first happened, I changed the scope, thinking it was the problem; but the drifting continued with a better scope. I am using 168gr SMK and 168gr Hornady HPBT and Lake City and Lapua brass; I have tried four different powders and even cheap 147 grain bullets. I am not getting pressure signs and loads are below maximum charges. It has an Aero Precision upper and toolcraft BCG.

FWIW, I own ten ARs and other rifles, and reload for 13 different cartridges. and can usually get MOA, even .5 MOA on all my AR pistols and rifles.

I have sent Faxon customer service two emails, and no response. I have a one shot AR barrel.

Sell the barrel and buy a different brand.

 

[bltmonty]

thanks everyone. I have checked the gasblock, and nothing is touching it; I did install the barrel nut with my high end mechanic's torque wrench and used locktite.

The charge weights on my loads are near maximum--by ejection marks and primers, so it's not a low charge weight; but I have not put the rounds through the chrony.

I posted my inquiry at the Faxon page on AR15.com. I hope to get some kind of response. I actually believe the barrel is flawed. I will let you all know what happens.

 

[BreechFace]

I posted my inquiry at the Faxon page on AR15.com. I hope to get some kind of response. I actually believe the barrel is flawed. I will let you all know what happens.

It would not surprise me in the least if it's flawed. I have a Faxon barrel that so far has been good, but as I said before there is a significant amount of online forum posts about issues getting Faxon's to group. The barrels look very nicely machined and really have great profiles, but seemingly their accuracy is hit or miss.

I think in a similar vein as Faxon one can get much better results with Ballistic Advantage barrels.

 

[illinoisburt]

Since it seems to be consistent I would suspect the barrel/receiver fit is not true. Pull the barrel nut and check that the barrel sits completely flush with the receiver all the way around. If there is a tiny gap somewhere in theory the tightened nut will pull things in tight but as metal heats and expands the barrel may move to close that gap then spring back as it cools. A couple thousandth may not be much but that enough to move point of impact significantly.

 

[BreechFace]

Since it seems to be consistent I would suspect the barrel/receiver fit is not true. Pull the barrel nut and check that the barrel sits completely flush with the receiver all the way around. If there is a tiny gap somewhere in theory the tightened nut will pull things in tight but as metal heats and expands the barrel may move to close that gap then spring back as it cools. A couple thousandth may not be much but that enough to move point of impact significantly.

This is a very good point that should be considered.

I always lap my upper receiver faces out of habit on my assemblies.

 

[Gordon]

And more than likely the consistence of the grouping travel when heated suggest that it indeed is a seating problem against the receiver . lathe turning then lapping would be best. You could try valve grinding compound lapping and looking at the pattern for full contact and reseating it to specs .

 

[bltmonty]

I will try this, thank you.

 

[ClemY]

Something that nobody mentioned, consider getting it cryo treated. If the barrel warps when it heats up, cyro treatment can cure that.

 

[mshootnit]

It would not surprise me in the least if it's flawed. I have a Faxon barrel that so far has been good, but as I said before there is a significant amount of online forum posts about issues getting Faxon's to group. The barrels look very nicely machined and really have great profiles, but seemingly their accuracy is hit or miss.

I think in a similar vein as Faxon one can get much better results with Ballistic Advantage barrels.

Well I guess that is why they judge a match barrel by the air gauge, and not the bore scope.

 

[illinoisburt]

I posted my inquiry at the Faxon page on AR15.com. I hope to get some kind of response. I actually believe the barrel is flawed. I will let you all know what happens.

Any updates?

 

[bltmonty]

no updates, whatsoever. I think I'm done with Faxon. After emailing customer service twice, starting in late March and a phone call two weeks ago, I certainly cannot rely on them.