*UPDATE* pg2

https://www.ar15.com/forums/AR-15/Did-I-buy-the-wrong-barrel-for-my-needs-6-5-grendel-/121-773542/?page=2#i8454306

Yes!
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20" faxon gunner 6.5g. Getting 2520fps with 123gr hornady black eldm factory ammo.

The Good:
New Grendel puts first 2 shots touching at 100y.

The Bad:
Opens up QUICK after that.

The Ugly:
Instead of waiting for the barrel to cool down, I pressed on anyway, blew through 30 someodd rds of eldm, then decided to try and be badass and hit a 10" gong at 700y in 20mph wind with last round of second box. Miss. Damnit. Came home, broke the whole thing down and rebuilt it, even relevelled and mounted the scope. So, now I basically have to do it all over again.

The Problems:
When I say blew through rounds though, no shot was taken less than 30 seconds apart, and there was time to cool while the range was cold. However, I did not wait 10+ minutes for each shot or shot group as I've seen and read of others doing with light profile barrels. This is after 2 range sessions with it (40 rounds each time, same everything else from time between shots to shooting conditions).
I also believe it is overgassed as the cases are dirty around neck and shoulder upon ejection, ejection is at 0200 with rifle tube, tubbs flatwire spring and rifle buffer. There were no ejector stamps on the bottom of the cases or flattened primers but definately exctractor pull marks.

The Preconceived Notion(s):
Now I've seen, experienced and even posted all the evidence of lightweight barrels still retaining darn good precision through heat build up, but this barrel went from two touching to 3 moa without mag dumping or even what I personally consider to be rapid fire really.

Possible Solutions:
I replaced the aluminum spacer in the rifle buffer with two steel weights from a spare carbine buffer (including rubber spacers) to bring the rifle buffer weight up to 6.1oz. during the rebuild. Stop waiting so long between individual shots and instead wait longer between groups. Rebuild should also solve any possible out of torque issues from original build.

My Needs:
1.5 moa minimum on demand and a 10" gong at 700 yards all while the barrel is warm (not hot, warm) would be nice (environmental conditions not withstanding ) as that's at least what I get with every other barrel I have.

Conclusion:
Do I need to change my ways, or my barrel?

Why did you not go with the 20" faxon heavy fluted match grade barrel? The fluting they do saves a ton of weight. That barrel would be much better for the type of shooting you are doing.

Poor reviews, both in text and video.

I wish I had more experience with more barrels and more shooting at distance with mine, but I have a 16” Gunner and it’s excellent. I’m not much of a target marksman, I just sighted it 2” high at 100 and it’s sub 1”, like yours is. I’ve not shot groups much beyond that. I just shoot furry brown things that make excellent table fare.

I wish you luck!

Barrel.

Personally never had much luck with rack grade barrels, Faxon or otherwise.  
On my Grendel and 6mm ARC I went through a couple of barrels, Odin Works and BA, to get where I wanted to be.  Only when I stepped up to a higher quality barrel did I see the consistent accuracy I wanted.  Ended up with a Proof Research stainless barrel on both.

Proof Barrel

Once you get everything on the build squared away or eliminated from doubt bring along another good shooter to shoot a cold group.  If the sequence of two tight, then group opening continues, or it doesn't group tight enough at all, then you can either chase ammo or chase barrels, or both. Being a nitrided  barrel I doubt it breaks in much.  You could try lapping the front rim of the upper receive’s barrel socket for even and full contact area.  You didn’t mention muzzle devices but that could have an impact.

Many Grendel extractors benefit from a little rounding of the “points” to get more area of extractor contact/engagement.  It wouldn’t surprise me if a Faxon barrel is a little generous on the gas port. Back when Wolf 100 grain was cheap, it got used even by precision oriented shooters for fun, and it needs a bigger gas port.

Good luck.

This is my story as well.  Same barrel, same vendor.  Also have one from XCaliber which is every bit on par with the Proof.

Budget barrels produce budget results.

So far, it does seem that this is a good hunting barrel.  If all someone wanted or needed was 1~2 shots, this barrel can do it. I am and was not looking for a an HBAR that I could blow through a hundred plus rounds with and still not care like a champ. But opening up to 3 moa in less than 40 rounds of what I consider to be relaxed shooting is disconcerting.

Thank you for the well wishes.

Damn, I had my eye on an Odin Works next.

My Odin Works barrel was ok but not the quality of the Proof barrel.  It functioned fine and as I recall it was a pretty solid 1-1.5 MOA barrel.

The Proof barrel is cut rifled, hand lapped and clearly higher quality.

I do plan on giving it another chance since the rebuild.

Yeah, being nitrided I don't expect any change after the first hundred rounds or so. Muzzle device is VG6 Gamma 6.5 with JP double crush washer and I torque all my crush washers like barrel nuts, 3 times while rotating the crush washer between each torquing to ensure even crushing and with the last time ending up in alignment. I never use a crush washer that has to be torqued more than just over 90° at most as well. I'm hesitant to knock off edges of the extractor as I believe the heavier buffer will help with what I believe to be overgassing, which now makes more sense as I forgot about steel case.

If things don't go as I would like next time out with it, I honestly think I'm just going to use the money the lapping tool and compound would cost on another barrel instead.

Good to know, thank you for the information.

I have had a damn good winning streak, I'm not complaing, just trying to verify if it's dead Jim.

Thank you for the follow up info.

I dunno, I have a 20" Faxon Gunner in my 6.5 Grendel and my groups don't open up like that when shooting quickly.  My accuracy has been really impressive actually.  Mine was a group buy and is 416R with 5R rifling like their match barrels but it's the same barrel profile.  I chose this barrel and profile because everyone was getting really good accuracy for punching paper while still being light enough to be carried for hunting.    

Of all of us who got these barrels I've not heard of any problems with groups opening up.  If my only purpose was punching paper and/or ringing steel, I'd definitely choose a heavy match barrel.  I'm actually liking this particular rifle so much I'm thinking of putting a heavy match barrel in it from Shaw or Criterion and putting the Faxon Gunner barrel in a dedicated hunting rifle.

Wow, you came all the way over here to say that?  

Do you handload?

Budget ammo produces budget results.  You can tailor a load that will shoot well in nearly anything but a BCA tomato stake.

But, thank you for that tidbit of wisdom

My 19.5 inch Satern 6.5 Grendel barrel is a tack driver.

Yeah, I only read of the group buy barrels and Monster seems to be like another barrel manufacturer that cannot be named here in that their barrels are great but you have to be dedicated to checking their website to see when they're back in stock every day. I went with this one because it was the same profile as the group buy with the only differences being 4150 (should actually handle heat better technically) instead of 416r and normal button rifling (and poor reviews of the fluted match kept me away from that one).

Maybe I goofed somehow on the first build, complacency kills, so I'll give it another fair shot since the rebuild.

As I posted above, I'm not looking for 100+ round count sessions, but say a 10 round group to confirm zero and then some unrushed gonging for let's say another 30 rounds should be within this barrel's capability.

I will also keep Satern in mind as well, thank you.

Yes, I reload, have been doing so for 35+ years including wildcats, I suppose you've missed some of my threads about budget barrels, bore scope stuff, and overall performance with various hand loads vs. factory fodder.

OP posted he's using Hornady 123 ELD-M factory ammo and you refer to that as budget ammo? Interesting.

OP's problem, correct me if I'm wrong, is the groups open up "quick".

At this point, OP suspects either the barrel or something in the build process is causing this. I'm awaiting his range results from rebuilding.

IF it happens to be the "quality" of the barrel, or more accurately a lack thereof, that results in poor performance when things heat up, how is any other ammunition going to change the results? OP himself stated "Poor reviews, both in text and video." when asked why he didn't go with a different Faxon barrel... so there's that.

I'm not a budget barrel hater, I have quite a few of them that shoot better than they should for the price point. Budget barrels are just that, budget options. You absolutely will get one here and there that shoots fantastic, but when they don't, the answer is quite simple... budget products produce budget results, barrels included.

Your wants/needs should be easily attainable with your barrel.  I'm more inclined to believe there's some other reason for your accuracy issues or you got a wonky barrel.  Have you contacted Faxon about this?

I doubt the "ejection chart" applies to a shorter/fatter case.

Factory ammo through a less expensive barrel should be in the 0.3-0.4 MOA mean radius realm at best. 30 seconds between shots should be plenty of time to shoot groups without risk of opening up noticeably.

The bore was cleaned well before the first shots, correct?

I had a faxon back when I first got into 6.5g. It did not like to shoot well after shot 3 or 4 within 5 minutes. I not once could shoot a consistent mag using the asc 9rd.

Found a deal on a Lilja and have always been more than happy with it. 4-5in plates at 525yds were almost a given even with the wind. My buddy was hooked on precision shooting after seeing and trying haha

FYI I've had much better luck with cheap BA barrels

I have yet to contact Faxon as I'd like to rule myself out of the equation as best as possible first. I believe the rebuild and another shot and even a second shooter are completely fair attempts at this. I am in no way upset with them or trying to cast shade on them. I knew going in that this is a $200 price range barrel, the skinniest profile barrel I own and it's not designed for extreme precision, but my results so far are outside my expectations which is why I created the thread.

The ejection pattern in conjunction with the fouled case necks and shoulders and extractor pull markings are what lead me to believe it's overgassed. Dunno. I'll try the heavier buffer (along with everything else being rebuilt) anyway.

The bore was cleaned prior to ever being shot by spraying hornady one shot (the cleaner not the case lube) down it and on the first couple inches of bore diameter portion of an otis ripcord and given 3 passes.

As crappy as it may seem to post, glad I'm not the only one to experience this.

I have been using asc 15rd 6.8spc mags loaded to 10 at most (after 1rd and lockback, then 3 rds feed and lockback checks).

I've had the same luck with BA and they're usually who I go with for this sort of thing.

Thank you for the vote of confidence in Lilja.

I have an Odin Works 6.5g barrel, BCG and gas block set.  The accuracy is kind “fair” at best.

It’s very ammo sensitive. It does well with a few bullets, and poorly with others. It really likes FGMM (.75 to 1 MOA) and shoots the no longer imported Wolf (2 - 2.5 MOA) better than I would have believed.

Thank you for the first hand experience info.

I have two BA 6.5G barrels one 18” and one 20”.

I thought at one time BA dropped the 6.5G but it shows on their site.

With hand loads and 8208XBR they hover around MOA and on occasion just under.

Thank you for the continued info.

Honestly at this point, I think if things don't go better next range trip, I'm just going to pull the barrel, contact faxon and move on. This was just supposed to be a quick cheap lark into 6.5g, nothing serious. I really had my heart set on 6 arc, but I found 123gr eldm for $26 a box (versus like $35 for 6 arc at the same time) and went with it instead.

I hold no animosity towards 6.5g or faxon and I have no plans on spreading this tale far and wide out of bitterness whatever the outcome. It is what it is, an alternative chambering I tried for fun that may or may not work out.

My BA 6ARC shoots under MOA both with or without suppressor... but as you mentioned, ammo is extremely expensive right now and availability is limited.

I hand load and have brass on back order since Oct 2020.

Hornady hasn’t supported the cartridge since its release, apparently more concerned with the PRC offerings.

This is the correct advice

Yeah, the single ammo source and cost is what's been holding me back from 6 arc as a non reloader.

Thank you as well for the info.

At this point I'm in a holding pattern as to what I'm going to do until next range trip as I would like to keep my original plan of relatively cheap fun dive in check before I go deeper.

This would be an easy fix to check on,

Sometimes the gas tube grows enough to contact the gas key and bottom out.

Move your gas block forward a few thousandths.

Then retest.

I went through several Grendel barrels.  Ended up with a 1/9 twist Alexander Arms 20" that shoots like a dream.

How is the barrel fit to the upper receiver OP.  I have a Friend lap the face of my upper receivers.  I then use blue Loctite on the barrel extension then torque to spec.  My 16” Faxon Group Buy Monster logo barrel is a good shooter.  I’m using a carbine buffer spring and supplied buffer.   My Faxon barrel has the correct gas port size and ejects cases to 3-4 O clock.   I have not noticed the groups on my two Faxon opening up on my 6.5 Grendel after so few rounds.   My Cz 527 American bolt action 6.5 Grendel is a different story, it’s hard to get through five rounds before it starts patterning.

You know, the gas block journal is long enough to accomodate a FSB, and the round not fully seating forward in the chamber could also explain the fouling on the neck and shoulder of ejected cases. I don't see the gas tube stretching as it's nitrided, but contact is still within the realm of possibility. Thank you for the reminder that sometimes you need to account for a lack of handguard end cap, I'll move the gas block up a touch.

Thank you for another good option.

I have a sneaking suspicion that I really do have a strictly hunting barrel (no more than say 3 shots in a short amount of time and then lots of downtime to cool completely) like your CZ and also posted above. Was really hoping for around say two boxes of liesurely shooting.

Sorry for the double quote, forgot to adress your barrel fit quesfion. The barrel fits snug in the upper receiver, not friction/thermal fit, and not slop/fall right in either, which is why it was never mentioned specifically. If it was sloppy, I would've also considered shimming or bedding the barrel extension into the upper as well. I don't think I'm going to go with receiver face lapping as I'm not looking for extreme precision with this build and I don't need it for any of my other builds, so I think I'd rather put that money towards another barrel instead.

<This. Some cheap barrels surprise people, many are a disappointment.

Your bench setup and technique play a huge role in how consistent your rifle groups.

With only 30 rounds downrange your barrel isn't even close to broken in. Clean it really well and try again, but this time slow.

I use an Uncle Buds Bag up front with a 2x12 board underneath if I need elevation. I use a Protektor bunny ear bag in the rear with rubber shims underneath to adjust elevation.

I never shoot a bipod off a bench (hard surface).

IMO SPR profile barrels are they best compromise of weight v. performance. You already spent your money, so try to work with what you have.

Wilson Combat makes excellent barrel in this caliber.

This is a good post.   In particular the break-in topic.  The 5.56 AR15 has spoiled us on how forgiving that system is.  a decade or 2 ago, the topic of "barrel break in" was said to be a thing of the past and no longer relevant.   And in 5.56, that seemed to be true even.   But in the last few years, I've learned that's not true at all in heavier calibers.  Even good high end stuff, often needs a few hundred rounds to really be smoothed out delivering at its full potential.  I've found this true in 6.5mm barrels, I'll say that.  I've run cheap PSA 6.5 Grendel barrels that shoot poorly at first, but over time tightened up.  Same with even a Ruger Precision Rifle 6.5CM barrel.  That shoot pretty good at first, and after a few hundred rounds, really tightened up.  A serious shooter of such told me that would happen, and it did.  

And I will absolutely agree that sometimes a cheap barrel can shoot amazing.   I've found with barrels the throat is a lot more important than people payed attention to - mostly because for the longest time it wasn't common to have the tools to investigate such.  And most of the attention given to the crown these days. But now that bore-scopes are cheap, and you can see the throat of a new barrel - you can very quickly see if the lands are starting uniform, or if it's off-center.  A rushed cheap barrel with an off-center throat where the left of the bullet hits lands before the right side does by a 1/16", is never going to be a good shooting barrel.  But you get a cheap barrel where it is correctly centered, and you'll be surprised how well they can shoot.

Just wanted to update this now that I'm back from vacation and prevent another safe thread. I drove to the range today, all bright eyed and bushy tailed, only to find it's closed for the weekend for private event... so on to next weekend...

I've addressed the barrel cost already. I have 80rds down the tube. All shot no faster than 30sec apart with a range cold in there as well. The barrel's also nitrided, so I don't believe the traditional breaking in and speeding up (maybe the speeding up) are applicable. I have shot everything else I own on a bipod and can easily beat 3 moa. Again, I fully understand this is the skinniest profiled barrel I own and it's going to heat up quick, but going from two touching to 3 moa in under 10rds seemed and still seems extreme to me. I agree a thicker profiled barrel should yield better precision all else being equal. Thank you for the continued support.

Thank you for the vote of confidence in WC, I will add this to the new barrel vote tally.

Were the barrels you mention in your first paragraph nitrided?
And again, I went into this fully understanding that this is a $200 skinny profile rack grade barrel. At no time was I under the delusion that I'd be shooting sub moa all day, but 3 moa is still unacceptable for me. This was just supposed to be a fun (relatively) cheap dive into the shallow end of 6.5g. I have plenty of other toys to hunt, shoot and defend my life with. Thank you for the continued help.

I have a 16” stainless fluted Alexander Arms that I built will do TEN rounds of Wolf into 1.4” at 100
Every Hornady load
ELDM
Black HP
SST
Old AMAX
And Speer Gold Dots
All shoot .75” or better
1x8 Primary Arms ACSS
Chevron and just bags
I read a ton of people having issues getting Grendel’s
To group on here and reloading groups
Why not go to “the source” who invented it
And the barrel blanks are Spanish stainless from Bergara that are rifled here and fluted
They are not terribly expensive either
The other positive is they shoot Wolf amazing and I bought quite a bit to blast this is a fun round to shoot

Thank you for the first hand info, I will remember it.