Group Buy barrels any good?

[Jorge0272]

I purchased a 12in and an 18in group buy barrel. Are they any good?
Every thread I see, seems to say if you want a good Sub MOA shooting rifle, you need to spend at least $400 on the barrel.
I have yet to shoot the 18in barrel, but I did shoot the 12in today. At 50 yards Iwould get a nice group, then a bad group, then a good group, then a bad group.
Wonder if its the scope, the ammo or the rifle? I was using handloads.
Hornady 120gr ELD-M
31.2 gr of CFE223
Hornady brass with CCI SFP
COAL: 2.26
Could it be this barrel does not like this bullet? At 50 yards I should be getting almost one hole groups.
This rifle is basically my "hunting" rifle, so not needing 1/4in group at 100, but I would like at least 1in group at 100.
Any suggestions to look at??

[A.D.D. AR]

If it you are using the 120gr Eld M (and not the 123gr Eld M) then seating depth is critical due to the ogive shape of the 120. with the 120 and a SAAMI chamber , the COL should be something like 2.18'' or so.
the 123 Eld m is a better choice for the Grendel- different ogive shape- much less picky on COL, and usually around 2.24'' or so.
If you don't have the Hornady comparator bushing set, you owe it to your reloads to get a set- it helps immensely. then you will know where each different bullet (Hornady 123 eldm, nosler 120 bt, sierra 107, etc.) hits the lands in YOUR chamber.
hope this helps

[VASCAR2]

Every barrel is unique and rack grade barrels are luck of the draw on their accuracy. The more expensive barrels generally will shoot a wider variety of ammo well and generally don’t need as much or any break in. I have a 12 inch PSA Nitride CMV 6.5 Grendel pistol and I find it harder to shoot accurately compared to my other 6.5 Grendel AR-15’s.

The Group Buy barrels get good reviews whether the original Faxon group buy barrels or the current Green Mountain barrels. Honestly if I can get 1-2 MOA accuracy with a rack grade barrel I feel lucky. I don’t cherry pick groups and generally base accuracy on five or ten shot groups.

If you really want to be sure your getting an accurate barrel I would look at Lilja, Shilen, Wilson Combat, Criterion or other higher quality barrels.

[A5BLASTER]

I purchased a 12in and an 18in group buy barrel. Are they any good?
Every thread I see, seems to say if you want a good Sub MOA shooting rifle, you need to spend at least $400 on the barrel.
I have yet to shoot the 18in barrel, but I did shoot the 12in today. At 50 yards Iwould get a nice group, then a bad group, then a good group, then a bad group.
Wonder if its the scope, the ammo or the rifle? I was using handloads.
Hornady 120gr ELD-M
31.2 gr of CFE223
Hornady brass with CCI SFP
COAL: 2.26
Could it be this barrel does not like this bullet? At 50 yards I should be getting almost one hole groups.
This rifle is basically my "hunting" rifle, so not needing 1/4in group at 100, but I would like at least 1in group at 100.
Any suggestions to look at??

What did the load work up look like? What's the jump for that bullet on your chamber?

Have you ever shot almostone hole groups are one hole groups at 50 yards before?

What scope/mount?

What trigger?

Did you accurize the build are just slap it togther?

Have you much experience shooting groups with the grendel are shooting groups with a grendel pistol?

If you want consistent sub moa then yes it's better to buy a better then rack grade barrel. The group buy barrels are good barrels but they are rack grade barrels, not to say that with good shooting technique and a well worked up load you can't get one to turn in consistent moa are smaller groups. It's just that if you want a almost 100 % chance that it will do that you have to step up to a better grade of barrel.

How much torque is on the muzzle device?

Is the gas block contacting?

Is the gas tube binding?

Did you use a ton of torque on the gas block screws?

Is the gun slightly over gassed are under gassed?

As you can see we need more details about you, the rifle, the load, the trigger, how you was shooting i.e. off the bench, bagged, bipod, offhand braced on a Miller can?

We need intel.

[Jorge0272]

I do not know what the jump is for the load.
Yes, I did shoot almost one hole 5 shot group with my 556 right before the Grendel.
Scope is a Athlon BTR 1-6X24. Mt 556 has a Vortex PST 1-4
Trigger is a 2 1/2 lb Rise Armament flat trigger.
This rifle was built correctly all to the correct torque specs.
Gas block does not even come close to the rail. There is not way it can touch the rail during fire.
Shooting was done on a bench. Placed the Vertical grip onto the bench to steady the shot. Not the best I know, but it worked.
I will be taking the upper apart and checking it out. Maybe buying the upper lapping tool and re-torquing everything.

[grayfox]

The 12" barrels are harder to shoot well IME, that being said I do all my load workups over a chrony, that way I can identify the powder charge that gets me onto a node. Did you do this? The advice on the 120 class Eldm is also good, you would be better to work up on the 123 Eldm.
My 12.5 was doing a node MV around 2280-2300 for 123 sst, what MV does your 31.2 get.

[Jorge0272]

Going to try some 123 ELDs and also some SMKs.
Going to also purchase some factory ammo, probably American Gunner, and see how those shoot.

[A5BLASTER]

Going to try some 123 ELDs and also some SMKs.
Going to also purchase some factory ammo, probably American Gunner, and see how those shoot.

Ok so let's break it down what we know so far.

Unknown load possible hot and contacting the lands.

Slapped toghter rifle not built to maximize the accuracy it can do.

Crappy bench technique and postion.

Correcttorque specs is complete diffrent from what is best for accuracy. Muzzle device torque, torque on the gas block screws and even torque on the barrel nut will effect your groupings.

Main point is it's not 223/556 do to having more bullet mass and more felt recoil you have to man up and drive the rifle more then you would the 22 cal.

Here is what I suggest.

Get some good bench bags and bag the front and rear of the rifle for shooting groups.

Get a better trigger maybe needed.

Drop the barrel nut torque to 35 or 40 foot pounds.
Retorque the gas block screws to no more then 15 inch pounds, 10 is better if your gas block will hold with that torque setting.

Pull the muzzle device throw away the crush washer and get the accuwasher system and time the muzzle device so it times and stays put with blue locktite and no more then 5 inch pounds of torque ( basicly handtight)

If there is money leavt for upgrade parts drop a lowmass bcg and standard weight buffer and spring in and adjust the gas for lock back.

Lapp the reciver face and get some steel shim stock in a roll and do a freeze and heat barrel bedding job on the barrel.

Then lose the handloads and try several factory loads that others are getting good groups with.

You never said are showed what the load work up looked like we have to assume you didn't do one and just dropped a load in the rifle. If that is true, you need to stop and don't shoot handloads anymore until you get the correct tools to measure jumps and headspace and a chrongraph to watch speeds and know when you have reached max or high pressure in your chamber.

Hope this helps sir.

[Jorge0272]

A5Blaster, thank you for the help.
Its been much easier to find good loads for 556, 300Blk and 308. I guess Grendel seems to be a lot more finicky.
At least the good thing is I am not looking for different loads for different purposes. One load and I am good.
Going to take apart the upper and re-torque with your specs and order the accuwasher system and some tools. Don’t know about the BCG right now.
Going to take a bit though, I am in the middle of moving.

[FLshooter]

From my experience, the more you spend on a barrel ,the higher percentage you have of it being accurate.So if you spend around $500+ on a custom barrel ,you?re pretty much guaranteed sub moa accuracy. Does not mean you can?t get sub moa accuracy out of a group buy barrel. Just not guaranteed.In the luck of the draw.And with the lower the quality barrel,it might take you 200 - 300 rounds to break it in.With a custom rifle it will shoot consistently out of the box.
And as many have pointed out to me in the past ,you need to add the price of the ammo it cost you to break in the barrel to the final cost. And you will realize that in the long run a quality custom barrel line up costing you less. Also quality barrels shoot well twice as long too.

[sbowhuntr]

My 20" gbb is shooting sub moa after only 50ish rounds down the tube. I also have 4 other green mountain barrels, 2-22lr, 223 and a muzzleloader barrel and all shoot sub moa. I must be lucky i guess.

[lazyengineer]

My 20" shoots OK, but not super great. With tuned ammo, mine can crowd to 1.5-2 MOA. For many applications I suppose that's just fine.


100 gr Nosler BTHP with 8208 (book-max = 30.8) (Single 5-shot groups, so not definitive)
28.1 - 2504 fps - 1.5 MOA
28.5 - 2520 fps - 3.2 MOA
28.8 - 2570 fps - 2.2 MOA
29.5 - 2612 fps - 4.0 MOA
30.0 - 2663 fps - 2.1 MOA
30.5 - 2716 fps - 1.7 MOA


One thing about Maloniting; I love it and my custom match-rifle .223 barrels that I use in competition are malonited by oil-field tool hardnening company. But beware that maloniting also short-circuits barrel break-in. Imperfections in the cut-job on a barrel, once malonited, are preserved and don't wear down so fast.

For the price-point, I still think the group-buy barrels are good deal, especially for just general purpose usage, and usage like the 12". I think one CAN get a cherry sub-MOA shooter; but like others said, for that price point don't just assume and expect every barrel in the pile to be a sub MOA Barrel.

[lazyengineer]

To follow-up, I used a Hornady OAL measurement tool to measure the chamber OAL to the lands, with every Grendel bullet I have. Very interesting results. The throat is not too long, and if anything, is actually rather short. Indeed, some of my loads likely were longer than the throat, though not all. At 200 rounds, which I consider about the proper round count to measure throat AOL (new barrels sometimes don't measure right), I got the following table - in order of bullet wt:

OAL to tip - Bullet for 20" Monster BBL @ 200 rounds of erosion.
[COLOR="#008000"]2.235" - 90gr Speer TNT (spitzer)

2.208" - 95gr H. V-Max (tipped BT)

2.135" - 100gr H. ELD-M (tipped BT)
2.220" - 100gr H. AMAX (tipped BT)
2.242" - 100gr Nos. Monster Match (Nosler Custom Competition, HPBT)

2.220" - 120gr H. ELD-M (tipped BT)
[/COLOR]2.312" - 120gr Speer Gold Dot (bonded semi-BT)
2.235" - 120 SMK (HPBT)

2.230" - 123gr Nos. CC (HPBT)
--- - 123gr H. SST
--- - 123gr H. ELD
--- - 123gr H. HPBT (don't have the above bullets loose in inventory)

2.220" - 129gr H. Interbond SP (lead tipped Spitzer)
[COLOR="#FF0000"]2.313" - 129gr H. SST (tipped BT)
2.370" - 129gr Nos. AccuBond (Tipped BT)

2.350" - 130gr Nos. RDF (HPBT)[/COLOR]
Note that measurements with this tool are not always precise and can be prone to error, and can easily be +/- 0.010" or more.

Where Green means the bullet OAL is SHORTER than magazine length (2.250"), before hitting the lands
and Red means the bullet AOL is LONGER than magazine length, before hitting the lands.
Which is to say Green means you aren't forced to an accuracy straining long bullet jump to reload, but there is potential for accuracy and safety issues if load them to magazine length.
And Red means can't really index a load off the lands and so subject to bullet jump, but magazine fed rounds can't be loaded so long they will be forced into the lands.

For my next batch, I will match my reloads to be at least 0.010" below this, and yet no more than 0.030", if I can. Some of these I've been running too long.

[grayfox]

Lze, roger on your point about meloniting - freezing in any barrel imperfections... this is one reason I have decided not to go for the mid-grade melonited barrels. Nothing against them but for me it was a roll-of-dice as to whether I got a relatively smooth surfaced barrel pre-melonite, or not... My current leaning is to crome-moly (some of my RAP's) or SS (Grrrs) plus a couple others. But good or great quality barrels to begin with.

I don't think I will shoot-out any of the barrels I have for quite some time; so if/when that time comes I will just re-barrel and keep on truckin'.

I would also offer that, to me, those do look like a pretty much shorty-group of OALs. Not a real happy spot to be in, I feel for ya.

[LRRPF52]

One thing about shooting 5.56 compared to Grendel is that your fundamentals have to change to get a lightweight Grendel to shoot as well.

5.56 ARs are very easy to group with for me as there is hardly any recoil at all.

With Grendel and AR10s, you have to apply more rearward pressure on the grip, pulling the stock straight into your stock weld into your chest or shoulder pocket, however you choose to place the butt for the best optical alignment of your eye to the scope without having to move your head to the rifle.

With the 2 samples of 12" Group buy barrels I used for 2 different builds, they both shoot under 1 MOA consistently with different loads and different shooters.

I check receiver face for squareness and bed the extensions. On one of these builds, it was an interference fit that required hours of pounding to get the barrel into the 2A Balios Lite upper.

I can rapid-fire 5rd Groups like this with both of them:



Other shooter zeroing and grouping:





We were shooting suppressed with Bootleg adjustable gas carriers, TBAC muzzle devices and cans, NightForce NX8 on one, 1-4x24 GRSC on the other.

The NX8 center dot covers the aiming point at 100yds, so it's harder to group with but still allowed us to turn-out the groups you see.

We were shooting 120gr Federal Match, 123gr Hornady American Gunner, and 123gr ELD-M Black ammo.

Also, from what I've seen in these chambers, I could load a 140gr way longer than magazine allowable, so I would expect the 120gr ELD-M to shoot well and not be subject to the Grendel's compound throat COL that does better with a secant 123gr.

The other 12" I built for a good friend shoots the 107gr SMK really well on top of 8208XBR for him.

[BluntForceTrauma]

LZE, how was it shooting at 100 yards?

[lazyengineer]

LZE, how was it shooting at 100 yards?

Limited data, as most of my development and test work is done at 200. I'm not sure if I've ever shot this BBL at 100 yards, but will check when I get the chance.

Next time I go out, I'll set some targets up at 100 as well.

[lazyengineer]

Using a Lyman Borescope, let's take a walk through the 20" Team BBL at 200 rounds. Be aware that borescopes can be tricky - one can easily misinterpret things; detritus from a dirty barrel can look like pits or other problems that aren't actually there. So this was done after a rather thorough cleaning.

Starting with the crown, and doing a rotation for each shot (i.e. 365 degrees of photos), to seek for any issues. Start with a rotation around the crown:









Crown looks sharp and good to me.

[lazyengineer]

Gas port going back to breach (Middle of bbl)


Looks OK. The maloniting is eroding out some. There's visible machining chatter to the bore, probably not ideal. The PSA BBL's are similar. Some of my more premium barrels in other calibers don't have this.

[lazyengineer]

hroat to breach



Interesting to see the rifling essentially goes all the way to breach, with a short forcing cone. Curious wear pattern between the lands, where the maloniting is really wearing out in that pattern. Not all maloniting is the same; I use a tool hardning company to malonite my 5.56 competition BBL's; and they don't have that between lands wearing off in the forcing cone quite like that. But that's a different chamber too.

Can see the tool chatter in the first photo.