New 6mm Advanced Rifle Cartridge

[Ledzep]

In regards to 18” barrels, what is the preferred gas length now that you guys have had some time shooting them? Standard rifle or a rifle +1”? This would be primarily suppressed.

Rifle+1 is awesome for ejection location of my brass pile in my 18" unsuppressed. Also runs slightly over gassed with a can but not bad. I'm running non adjustable $20 gas block.

 

[Southern Custom]

Rifle+1 is awesome for ejection location of my brass pile in my 18" unsuppressed. Also runs slightly over gassed with a can but not bad. I'm running non adjustable $20 gas block.

Glad to hear your plus 1” is running.
I’m running Odin’ rifle plus 2 and I can firmly state it’s a nightmare with a carbine buffer system. The first block they sent me was leaking like a sieve. I switched to a Aero fixed block and immediately got lock back with 108 ELDMs but with 87g vmax it won’t strip the next round.
they sent me a new block which was much tighter and I figured I was good to go. Nope. Apparently it leaks around the front of the gas tube which is open on the Odin block vs closed for the Aero. Also leaking a bit from the adjustable set screw. I got lock back only half the time on my hottest loads. So I’m yanking the new one back off and going back to the Aero block. Don’t know what the hell Odin was thinking with this system. Even with a .101 port it still doesn’t get enough gas with only 2” of barrel in front. I suppose I’ll throw the Odin block on one of my over gasses Aero uppers. I’m sure it will eventually seal itself off. And maybe it’s a good excuse to finally buy a can.
On a positive note at least the barrel shoots fairly tight.

 

[r.tenorio671]

Glad to hear your plus 1” is running.
I’m running Odin’ rifle plus 2 and I can firmly state it’s a nightmare with a carbine buffer system. The first block they sent me was leaking like a sieve. I switched to a Aero fixed block and immediately got lock back with 108 ELDMs but with 87g vmax it won’t strip the next round.
they sent me a new block which was much tighter and I figured I was good to go. Nope. Apparently it leaks around the front of the gas tube which is open on the Odin block vs closed for the Aero. Also leaking a bit from the adjustable set screw. I got lock back only half the time on my hottest loads. So I’m yanking the new one back off and going back to the Aero block. Don’t know what the hell Odin was thinking with this system. Even with a .101 port it still doesn’t get enough gas with only 2” of barrel in front. I suppose I’ll throw the Odin block on one of my over gasses Aero uppers. I’m sure it will eventually seal itself off. And maybe it’s a good excuse to finally buy a can.
On a positive note at least the barrel shoots fairly tight.

...I've found that gas blocks that use the 2 setscrews on underside for retention are more prone to leakage than the clamp type of gas blocks. In the non-clamp types, lack of dimpling can exacerbate that leakage, sometimes, all depending on the fit of the gas blocks ID to the barrel gas journal's OD. I use both. Handguard selection for "clearance" of the type of gas block (set -vs- clamp) can be a factor. I have seen that set screw types will over time eventually resolve leakage once enough rounds have been fired that carbon build-up seals those loose fitting areas.....

 

[Yondering]

Glad to hear your plus 1” is running.
I’m running Odin’ rifle plus 2 and I can firmly state it’s a nightmare with a carbine buffer system. The first block they sent me was leaking like a sieve. I switched to a Aero fixed block and immediately got lock back with 108 ELDMs but with 87g vmax it won’t strip the next round.
they sent me a new block which was much tighter and I figured I was good to go. Nope. Apparently it leaks around the front of the gas tube which is open on the Odin block vs closed for the Aero. Also leaking a bit from the adjustable set screw. I got lock back only half the time on my hottest loads. So I’m yanking the new one back off and going back to the Aero block. Don’t know what the hell Odin was thinking with this system. Even with a .101 port it still doesn’t get enough gas with only 2” of barrel in front. I suppose I’ll throw the Odin block on one of my over gasses Aero uppers. I’m sure it will eventually seal itself off. And maybe it’s a good excuse to finally buy a can.
On a positive note at least the barrel shoots fairly tight.

This is a perfect example why I say the current fad of running extra long gas systems is misguided. On anything between 18" and 24", just use standard rifle gas. If the port is sized correctly (or gas is restricted correctly at the gas block) it'll run really nicely with no problems.

There's no good reason to try to use such short dwell time; it requires overly large port sizes which are not beneficial.

 

[Stevenhansell]

Has anyone loaded any of the Berger bullets yet? I’ve got 87 vld hunting, 95 classic hunter, and 105 vld hunting. Just curious how they shot on paper and any issues before I use up powder and primers trying them out. Have some hornady 105 bthp I’m going to load as well. Some 100 grain partitions but probably will leave those alone till before deer season next year. Still working through all the factory ammo I bought.

 

[ormandj]

Rifle+1” for 18” is great.

On that barrel, looking at the shoulder and crown, it looks like the machinist didn’t properly center the barrel before cutting. I’d be asking for a new barrel if I were you, I’d be worried about the threading being concentric to the bore.

 

[Silverjay]

Has anyone loaded any of the Berger bullets yet? I’ve got 87 vld hunting, 95 classic hunter, and 105 vld hunting. Just curious how they shot on paper and any issues before I use up powder and primers trying them out. Have some hornady 105 bthp I’m going to load as well. Some 100 grain partitions but probably will leave those alone till before deer season next year. Still working through all the factory ammo I bought.

I ran a few of the 95 classic hunters, they shot well. I didn’t get the velocity out of them I was looking for. According to my notes I was getting 2,720 with CFE.

 

[ormandj]

This is a perfect example why I say the current fad of running extra long gas systems is misguided. On anything between 18" and 24", just use standard rifle gas. If the port is sized correctly (or gas is restricted correctly at the gas block) it'll run really nicely with no problems.

There's no good reason to try to use such short dwell time; it requires overly large port sizes which are not beneficial.

It's not misguided to want to run a longer length gas system; this is just a great example of people making barrels who have no business doing so, because they clearly don't understand how to properly setup a gas system. I suspect I'm preaching to the choir here, but for other's sake, having a longer gas system is beneficial in a lot of ways, since you're allowing the chamber pressure to drop since the BCG movement/bolt unlocking is happening later. You obviously have to have the proper gas impulse on the piston (BCG) to cycle the action, which is driven by the correct combination of dwell time and gas port sizing, along with the cartridge in question.

Going rifle + 2" on an 18" is cutting it too close (gas is flowing to the BCG only during the time between the bullet passing the port and exiting the barrel) and would require a silly-large gas port to have a chance at functioning properly. On a 18" 6mm ARC, rifle+1" seems to be the best compromise in being softer shooting/cleaner while still maintaining full functionality with all types of ammunition. The only real downside is less availability of gas tubes in the rifle + 1" size.

I get very frustrated watching people struggle with poorly performing AR15s because someone chambered them barrels with improper gas port sizing/gas system lengths. It's beyond frustrating for the end users, and it only takes a little work to determine the proper setup on new cartridges. I don't know if it's laziness or what, but it really is disheartening to see these poorly setup gas systems leaving any shop.

 

[Yondering]

It's not misguided to want to run a longer length gas system; this is just a great example of people making barrels who have no business doing so, because they clearly don't understand how to properly setup a gas system. I suspect I'm preaching to the choir here, but for other's sake, having a longer gas system is beneficial in a lot of ways, since you're allowing the chamber pressure to drop since the BCG movement/bolt unlocking is happening later. You obviously have to have the proper gas impulse on the piston (BCG) to cycle the action, which is driven by the correct combination of dwell time and gas port sizing, along with the cartridge in question.

I'll repeat: The current fad of going to extra long gas systems is misguided. Too many people can't think beyond "some is good, more must be better".
Anything more than rifle length on an 18" is unnecessary. At that point it's not the gas system length that matters, but the port size. A longer gas system than that just makes the system more finicky about what ammo it will shoot reliably. Even in a 24" with this cartridge, standard rifle length works great, IF THE GAS IS TUNED CORRECTLY. That last part is pretty important, and too many low information gun owners try to avoid it by using a longer gas system instead.

There is no good reason to push an extra +1" length on that gas system, other than to validate your own choices. There's nothing magical about an extra 1" longer; it just needs a larger gas port.

 

[Southern Custom]

I'll repeat: The current fad of going to extra long gas systems is misguided. Too many people can't think beyond "some is good, more must be better".
Anything more than rifle length on an 18" is unnecessary. At that point it's not the gas system length that matters, but the port size. A longer gas system than that just makes the system more finicky about what ammo it will shoot reliably. Even in a 24" with this cartridge, standard rifle length works great, IF THE GAS IS TUNED CORRECTLY. That last part is pretty important, and too many low information gun owners try to avoid it by using a longer gas system instead.

There is no good reason to push an extra +1" length on that gas system, other than to validate your own choices. There's nothing magical about an extra 1" longer; it just needs a larger gas port.

So your comment begs the question. How large of a gas port can you run on a system like this. Since I’m now stuck with this ridiculous Odin barrel, I’d like to try and get this thing to run decently with more than the one load it functioning with now. I can feed it 108s all day long and it functions fine with the .101 port. As soon as I tried 87g it’s a no go. Won’t strip or lock back. I’ll throw on a reduced power spring next trip but I had to laugh when I pulled the Aero fixed block and replaced it with a new Odin tunable block they mailed me as a replacement for the first one that was way out of spec, and a tiny amount of leakage around the gas tube was enough to cause failure to lock back. Which of course means it’s running on the razors edge of functioning. I’ll be firing off another letter to Odin this week. We’ll see if they’ll exchange it for a 20” but I don’t have high hopes.
this has been a learning experience so thanks for the input.

 

[ormandj]

I'll repeat: The current fad of going to extra long gas systems is misguided. Too many people can't think beyond "some is good, more must be better".
Anything more than rifle length on an 18" is unnecessary. At that point it's not the gas system length that matters, but the port size. A longer gas system than that just makes the system more finicky about what ammo it will shoot reliably. Even in a 24" with this cartridge, standard rifle length works great, IF THE GAS IS TUNED CORRECTLY. That last part is pretty important, and too many low information gun owners try to avoid it by using a longer gas system instead.

There is no good reason to push an extra +1" length on that gas system, other than to validate your own choices. There's nothing magical about an extra 1" longer; it just needs a larger gas port.

We'll have to agree to disagree on this one. I prefer rifle + 1" on my 18" barrels, and I've turned/ported plenty of both lengths to experiment with. I'm not attempting to "validate" my own choices by pushing anything; I made the choice for my own barrels based on experimentation. I don't sell barrels to anyone, in fact my lathes are in storage right now so my 6mm ARC barrels I had chambered/turned/ported by Craddock, also in +1" because it's what I prefer. Either way, +2" on an 18" barrel is a bad plan, even with a crazy large port. I definitely agree in that regard, and also agree that standard rifle length can work fine with proper port sizing. I do not think it's optimal, but it definitely makes buying gas tubes easier, and it's not night and day different.

 

[ormandj]

So your comment begs the question. How large of a gas port can you run on a system like this. Since I’m now stuck with this ridiculous Odin barrel, I’d like to try and get this thing to run decently with more than the one load it functioning with now. I can feed it 108s all day long and it functions fine with the .101 port. As soon as I tried 87g it’s a no go. Won’t strip or lock back. I’ll throw on a reduced power spring next trip but I had to laugh when I pulled the Aero fixed block and replaced it with a new Odin tunable block they mailed me as a replacement for the first one that was way out of spec, and a tiny amount of leakage around the gas tube was enough to cause failure to lock back. Which of course means it’s running on the razors edge of functioning. I’ll be firing off another letter to Odin this week. We’ll see if they’ll exchange it for a 20” but I don’t have high hopes.
this has been a learning experience so thanks for the input.

I wouldn't try to fix it, Odin should make it right for you. The largest gas ports I see (7.62x39/300BO/etc) are 0.125". You have to remember your problem is the short time between the bullet passing the gas port before exiting the muzzle and the reduced pressure at that port during this time due to the distance from chamber/room for gas expansion/etc. I just don't see why you should be trying to fix their mistake for them. I have no idea if they'll exchange it for a longer barrel, but I wouldn't switch to a longer barrel due to your issues - just an appropriately setup gas system. They owe you a functioning barrel, not a finicky mess.

 

[Nikon147]

Due to basically every barrel maker being out of stock or having incredible lead times, I went with a BA 18" from Brownells. Geissele gas block that came with the Mk4 rail I put on it. Rifle Gas, with an H2 Buffer. ASC Grendel Mags.

Shot it for the first time this weekend. Ejecting right at 330/4 oclock. Barrel didn't shoot so well to start, but settled in after a couple strings. 1 malfunction with the mags (I have 4 and used all of them), so pretty good overall.

I'm going to have to go back again to really get a feel for the accuracy, one of the rings on my Larue mount cracked and I'm thinking some of the spread on my later groups was related to that.

Did manage to get two good 5 round groups, each under an inch at 100, so I'll take it for an inexpensive barrel and factory ammo.

I was shooting the Hornady Match 108gr.

Pretty neat little round.

I put new rings one when I got home, and I'll report back once I can get back out to the range.

 

[Yondering]

So your comment begs the question. How large of a gas port can you run on a system like this. Since I’m now stuck with this ridiculous Odin barrel, I’d like to try and get this thing to run decently with more than the one load it functioning with now. I can feed it 108s all day long and it functions fine with the .101 port. As soon as I tried 87g it’s a no go. Won’t strip or lock back. I’ll throw on a reduced power spring next trip but I had to laugh when I pulled the Aero fixed block and replaced it with a new Odin tunable block they mailed me as a replacement for the first one that was way out of spec, and a tiny amount of leakage around the gas tube was enough to cause failure to lock back. Which of course means it’s running on the razors edge of functioning. I’ll be firing off another letter to Odin this week. We’ll see if they’ll exchange it for a 20” but I don’t have high hopes.
this has been a learning experience so thanks for the input.

The inside of a gas tube is about .125”, so there’s not much benefit to going larger than that other than to account for some leakage at the gas block. I wouldn’t recommend that route myself though; done that and it’s less than ideal. Hopefully Odin will make it right with a different barrel that runs correctly.

Or load all your ammo with Leverevolution; the extra gas will make it run. I say that in jest, but there’s truth there too.

Seriously though, what you’ve described is exactly why this long gas system fad is so stupid. In an attempt to avoid gas tuning and still have a smooth shooter, people are ending up with barrels that are finicky about what ammo they’ll run. It’s a very similar effect to using extra light bolt carriers, but the same people who’ll tell you not to do that will recommend a longer gas system because that’s the fad right now.

In contrast, using a mid length or rifle gas system in the same barrel, when tuned correctly, will enable you to shoot both loads comfortably, within reason. In my experience anyway. Hopefully Odin will set you up that way, or with a longer barrel.

 

[Yondering]

We'll have to agree to disagree on this one. I prefer rifle + 1" on my 18" barrels, and I've turned/ported plenty of both lengths to experiment with. I'm not attempting to "validate" my own choices by pushing anything; I made the choice for my own barrels based on experimentation. I don't sell barrels to anyone, in fact my lathes are in storage right now so my 6mm ARC barrels I had chambered/turned/ported by Craddock, also in +1" because it's what I prefer. Either way, +2" on an 18" barrel is a bad plan, even with a crazy large port. I definitely agree in that regard, and also agree that standard rifle length can work fine with proper port sizing. I do not think it's optimal, but it definitely makes buying gas tubes easier, and it's not night and day different.

We’ll definitely disagree then. Do you know what a self fulfilled outcome is? If you can tell that much difference in 1” of gas system, then your gas tuning needs work.

I’ll also point out that you seemed pretty green at the start of these 6mm ARC discussions this year, so I’m having a hard time believing your claimed experience in barrel turning. When I’ve tuned gas systems of different lengths within a few inches of each other, you can’t tell the difference in feel or effect on the brass, but one is definitely more picky than the other. When I say tuned, I mean actually tuning each one, not just using the same gas port size for each and concluding the longer one shoots softer.

IMO your promotion of this fad of extra long gas systems is pretty bad advice.

 

[MichiganMitten]

We'll have to agree to disagree on this one. I prefer rifle + 1" on my 18" barrels, and I've turned/ported plenty of both lengths to experiment with. I'm not attempting to "validate" my own choices by pushing anything; I made the choice for my own barrels based on experimentation. I don't sell barrels to anyone, in fact my lathes are in storage right now so my 6mm ARC barrels I had chambered/turned/ported by Craddock, also in +1" because it's what I prefer. Either way, +2" on an 18" barrel is a bad plan, even with a crazy large port. I definitely agree in that regard, and also agree that standard rifle length can work fine with proper port sizing. I do not think it's optimal, but it definitely makes buying gas tubes easier, and it's not night and day different.

What size gas port for a 22" +2 gas, non-supressed?

 

[ormandj]

What size gas port for a 22" +2 gas, non-supressed?

Unfortunately I've not tested this combination, I have no idea.

 

[ormandj]

We’ll definitely disagree then. Do you know what a self fulfilled outcome is? If you can tell that much difference in 1” of gas system, then your gas tuning needs work.

I’ll also point out that you seemed pretty green at the start of these 6mm ARC discussions this year, so I’m having a hard time believing your claimed experience in barrel turning. When I’ve tuned gas systems of different lengths within a few inches of each other, you can’t tell the difference in feel or effect on the brass, but one is definitely more picky than the other. When I say tuned, I mean actually tuning each one, not just using the same gas port size for each and concluding the longer one shoots softer.

IMO your promotion of this fad of extra long gas systems is pretty bad advice.

I've been turning barrels for rifles for almost two decades now (as well as other lathe/mill/metalwork operations on firearms and non-firearms alike), but I am relatively new to AR15 barrels, and certainly very new to 6mm ARC compared to bolt action rifles. I don't see how that invalidates me turning multiple barrels, experimenting with gas system lengths and gas port sizing until I found what worked best for me on AR15s? I've done this on a few different cartridges and found it holds true across most of them running in the same pressure range, so I've quit experimenting on every single cartridge, though I do tend to port undersized and then increase port sizing as necessary for the lowest pressure ammunition I intend to run. I don't like being overpassed, especially as I primarily shoot suppressed, but I don't have a single AR15 here that has any reliability issues even with lighter ammunition, because I always port to ensure function with the lower pressure garbage in case I ever find a need to run it. I solve the gas issue with suppressed use with an AGB. I'm waiting on a third Bootleg adjustable carrier now; we'll see how these work before I go back to non-adjustable gas blocks.

Yes, I know what a self-fulfilling prophecy is. I would *prefer* standard rifle length, if it performed the same. It didn't, for me. I'm biased towards standardized parts, not against them...

Cutting a barrel blank down, turning it, chambering it, and porting it are all very simple operations. Doing this on a few barrels with minimum port sizing and two different gas lengths, comparing them side by side as you enlarge the port isn't exactly hard. It's not "that much difference", I've already stated it's *not* night and day different. Perhaps you misread that part? Either way, I'm done going down this rabbit hole, believe what you want. I still agree rifle + 2" is bad on 18", but I do think rifle + 1" is better (slightly) than rifle length, if both are ported properly, based on my experience. I'd rather have a straight rifle lengthen than a + 2", so we are clear.

 

[newageroman]

Some results...I was using the 4x and BDC to get to 1k. I was able to get a couple other hits on the sighing plate, but spotting became an issue so I stuck with 600/750. At 12x I'm holding the last circle, and at 750 I'm holding the point of the bottom post about 6" above the top of the target.
Notice my sighing shot on the big plate, then when I spotted hits on the bottom of it I just skipped the normal sized silhouette and went directly to the smaller one and got 3/4 hits. The swingers at 600 were also pretty fun, I feel sure I could go 1 swinger smaller.
I got to try some annealing with the AMP which was cool.

Overall digging this cartridge. more to come.

 

[TonyTheTiger]

What size gas port for a 22" +2 gas, non-supressed?

.100 ish on my 6 Grendel in that configuration. It still borders on undergassed with some loads. Starting over I'd probably go +1" gas.

 

[SBRSarge]

I finally shot my 6ARC. I only put ten rounds down range at 100yds. The first five were the Hornady Black load and got a 1.03 group. The next five were the ELD-M load and that grouped into a vertical 1.13” group. Horizontal spread on this second group was about .15”.

I’m happy, I was shooting more to check the function of my build break in the barrel, and was only half-assed worrying about group size. As the barrel gets worn in, I expect great things from this gun. I expect that I will as usual be the weak link.

I didn’t chrono the shots, but will next time I shoot when it hopefully is warmer.

The upper is a BCM into which I thermal fit an 18” Odin barrel. Shooting was done with my Omega can.

 

[Fret]

Has anyone here used H380 for bullets around 105 grains in the 6 ARC? I have powder that should work well with lighter bullets but not so well with these heavier bullets. Leverevolution seems to be a good one but can't seem to find any but found some H380 which is right next to Leverevolution on the burn chart. Got an ARC build in progress and just waiting on the CLE barrel.

 

[godofthunder]

Got my ARC out finally to do a little bit of shooting. Functioning great and the impact on steel at 250 yds compared to 223 is impressive. My razor 1-6 left me wanting more magnification though, so guess I'm on the hunt for a new scope for my rig.

 

[SWFShooter]

I tried it

Interesting, what cartridge were you loading it in? I've only used it in .30-06, and it has done well velocity-wise with a few different bullet weights, but I've read posts by plenty of folks that seem to be happy with it in 6mm GT, 6.5 CM, and 7mm-08.

That said, I think it's probably too bulky for best velocity in 6mm ARC, I've always heard that compressing ball powder can get peakier, quicker than most extruded. The StaBall ARC data on the Hodgdon site is compression limited and fairly anemic:

103gr VTAC - 30.7C gr @ 2,611 fps
107gr Sierra hpbt - 30.0C gr @ 2,557 fps
110gr A-Tip - 30.3C gr @ 2,555 fps

That's from a 24" barrel, they have a few different powders that are faster, and CFE 223 is much faster.

I tried it with 88s in 223, it was 50-75 fps slower than Varget, and very compressed to get there. Tried it in 6mm Grendel, which is very close to 6mm ARC, and again couldn't pack enough in there to get velocity up, about like the . Just too small of a case for that bulky of a powder. With the big case like the 30/06, you can get enough in the case to be scary, but should see decent velocity without having to push pressure. My 6mm Grendel results are comparable to that new 6mm ARC data on the Winchester page, I was referring to the Hodgdon Reloading data for 224 Valkyrie which shows it is faster than CFE223 with 90s...that never happened. Without a hydraulic press to seat bullets.

 

[Dino11]

Glad to hear your plus 1” is running.
I’m running Odin’ rifle plus 2 and I can firmly state it’s a nightmare with a carbine buffer system. The first block they sent me was leaking like a sieve. I switched to a Aero fixed block and immediately got lock back with 108 ELDMs but with 87g vmax it won’t strip the next round.
they sent me a new block which was much tighter and I figured I was good to go. Nope. Apparently it leaks around the front of the gas tube which is open on the Odin block vs closed for the Aero. Also leaking a bit from the adjustable set screw. I got lock back only half the time on my hottest loads. So I’m yanking the new one back off and going back to the Aero block. Don’t know what the hell Odin was thinking with this system. Even with a .101 port it still doesn’t get enough gas with only 2” of barrel in front. I suppose I’ll throw the Odin block on one of my over gasses Aero uppers. I’m sure it will eventually seal itself off. And maybe it’s a good excuse to finally buy a can.
On a positive note at least the barrel shoots fairly tight.

I posted this a while back, I had every type of malfunction you can imagine, feeding, firing, and ejection.

This is what worked for me and the rifle runs 100% since the fix.



Odin barrels are +2 on the rifle length gas system.

I have one of their 18" barrel with the +2 gas port. My gas port is .101 per the folks at Odin.

I was having the same issue as you, I think it is because the gas port is so close to the end of the barrel and does not give the gas enough time to fully cycle the BCG. I to was running my gas block fully open.

My rifle has a rifle length RE and stock, I called Odin to see if they had a fix for it and they stated they had only tested this system with a carbine length RE and buffer. So I was pretty much on my own to try and figure this out.

My fix for it was to remove 4 of the 5 steel wieghts out of the buffer and replace them with aluminum weights I made from 1/2" bar stock. This lowered the buffer weight from 5.2 oz to 3.4 oz, I then added a Wolff 10% reduced power action spring and all was good. I was able to adjust my gas block to almost closed position and the rifle is a very soft shooter. and because I am sending so little gas to the BCG the rifle barely gets dirty..

If I was you I would start with a reduced power buffer spring and see if that fixes your problem, you might want to try a different mag as well and don't fully load it. Try loading it with only two rounds and see if you get bolt lock on last round.

 

[Southern Custom]

Update on the Odin 18” rifle +2 barrel. Got it to run fine with 108 ELDMs. The 87g load wouldn’t strip or lock back so it was a single shot with that load. It took removing the first adjustable gas block they sent and replacing with a fixed Aero block. They sent me a second block that was a better fit but it leaked around the front of the gas tube which on this block is exposed. So back to the Aero fixed block for the second time.
Next I quit messing about and opened up the gas port to .125. This coupled with a 3oz buffer and reduced power spring and it locks back with the 87grain loads now as well. Ran it this way today for the first time and it’s finally sorted out. Barrel is putting up .5” groups with Lever and 108s. And .5 with H335 and 87g Vmax . Knowing what I know now I have to ask what the hell were they thinking with this barrel. Rifle length would have been fine. Even rifle plus 1” would have been ok. Plus 2 simply lacks the dwell time for consistent function. I’ve asked around and every person who has posted about this barrel has gone same crap. Hopefully Odin listens to our feedback and makes a change.

 

[TonyTheTiger]

@Southern Custom Odin just got sucked into the long gas system hype without really understanding what they were doing. You see that a good bit in the AR aftermarket with companies that mostly just try to ride popularity waves and have decent production capability but lack real interest in more technical knowledge of firearms. You can always spot these companies in product release vids from SHOT when the company owners describe their own products incorrectly while reading some very rudimentary knowledge off of a brochure.

 

[Triple D]

Yeah. When I first heard they were doing a +2 on an 18”, it left me scratching my head. Maybe a +1...but a plus 2 just didn’t seem like a smart move and is just asking for trouble.

 

[TonyTheTiger]

Yeah. When I first heard they were doing a +2 on an 18”, it left me scratching my head. Maybe a +1...but a plus 2 just didn’t seem like a smart move and is just asking for trouble.

Exactly. And I'm a guy that has a couple rifle gas 16" barrels, an intermediate 15" and 14.5" and a mid 12.5". So I really like pushing the limits of gas system lengths, but those aren't barrels for widespread sale to just anybody that can assemble an AR.

 

[alamo5000]

Can someone please do me a favor? This can be done with factory ammo or virgin brass that has been loaded.

Please measure the OD of the case neck after the bullet is seated (at it's widest point). At this point I assume everyone is using only Hornady brass.

If you can measure 4 or 5 cases so I can get an average, that would be very helpful.

Thanks!!!

 

[Dino11]

Update on the Odin 18” rifle +2 barrel. Got it to run fine with 108 ELDMs. The 87g load wouldn’t strip or lock back so it was a single shot with that load. It took removing the first adjustable gas block they sent and replacing with a fixed Aero block. They sent me a second block that was a better fit but it leaked around the front of the gas tube which on this block is exposed. So back to the Aero fixed block for the second time.
Next I quit messing about and opened up the gas port to .125. This coupled with a 3oz buffer and reduced power spring and it locks back with the 87grain loads now as well. Ran it this way today for the first time and it’s finally sorted out. Barrel is putting up .5” groups with Lever and 108s. And .5 with H335 and 87g Vmax . Knowing what I know now I have to ask what the hell were they thinking with this barrel. Rifle length would have been fine. Even rifle plus 1” would have been ok. Plus 2 simply lacks the dwell time for consistent function. I’ve asked around and every person who has posted about this barrel has gone same crap. Hopefully Odin listens to our feedback and makes a change.

I'm surprised that Odin did not tell you about using the reduced power spring and lighting the buffer. I have one of their first barrels so I was on the front side of the 6ARC, as they were one of the first manufacture of the barrels. I got in before all the damn Pandemic hype going on and nobody could get anything because everybody wanted something all at the same time.

I called them and relayed the information on the fix as they had no information on what to do as they said that they only tested it with a carbine length buffer system and it worked fine for them. I also had to go through the 105 Black box ammo ordeal, I actually worked with Odin and Hornady to get this figured out. So I was very discouraged at first with the 6ARC, it was one problem right after another. Didn't you get an adjustable gas block and tube with your barrel?

 

[Gtscotty]

I wish I had read about all these problems with the OW barrel function before I bought one, most of the accuracy reviews I found were good. It blows my mind that a barrel manufacturer producing a precision focused cartridge like the 6mm ARC could just skip function testing with rifle buffer systems.... That's really, really dumb.

Have the problems been only with rifle buffer systems, or have carbine buffer systems been problematic as well (say with lighter bullets)? I have some 70gr TNTs and 85gr GKs I want to try, maybe with 8208.

OW did pay for shipping to repair the honked up muzzle threads on my barrel, which is as it should be.

 

[Dino11]

I can't speak as to if carbine has a problem, I have three 6Arc rifles and they all have rifle length Buffer systems.

My other two barrels are Faxon 18" and 20", these two are standard rifle length gas port and neither of them had any issues. I will add that the Odin barreled rifle is by far the softest shooting by a huge margin. They all have the same muzzle device, the Odin Atlas. And the Odin barreled gun stays much cleaner shooting the same amount of ammo through it. The Leverevolution powder is not the cleanest burning powder, but it is my go to after using many other powders. A friend of mine has a BA barrel and of all the 6ARC's I shot the Odin barrel is the most accurate, prints consistent .3 MOA @ 100 yards with my hand loads.

 

[Gtscotty]

I can't speak as to if carbine has a problem, I have three 6Arc rifles and they all have rifle length Buffer systems.

My other two barrels are Faxon 18" and 20", these two are standard rifle length gas port and neither of them had any issues. I will add that the Odin barreled rifle is by far the softest shooting by a huge margin. They all have the same muzzle device, the Odin Atlas. And the Odin barreled gun stays much cleaner shooting the same amount of ammo through it. The Leverevolution powder is not the cleanest burning powder, but it is my go to after using many other powders. A friend of mine has a BA barrel and of all the 6ARC's I shot the Odin barrel is the most accurate, prints consistent .3 MOA @ 100 yards with my hand loads.

Sounds like if it runs reliably, it might be ok. Mine will be suppressed pretty much all the time, so that might help.

When I ordered the Odin, I honestly thought it was a +1 gas system, not sure why, I must have confused the specs with the proof barrels I was looking at too. What handguard length are y'all using with the +2 gas system? Will a 15"-15.5" cover at least the tube and part of the block or is longer necessary? I'd love to see pics of the handguard setups people are running with these +2 barrels.

 

[Fret]

Can someone please do me a favor? This can be done with factory ammo or virgin brass that has been loaded.

Please measure the OD of the case neck after the bullet is seated (at it's widest point). At this point I assume everyone is using only Hornady brass.

If you can measure 4 or 5 cases so I can get an average, that would be very helpful.

Thanks!!!

Luckily I was able to find some Hornady Match and Black 6 ARC ammo for my new project so I measured several from each box with my micrometer. The loaded necks varied from 0.2695 to 0.2705. I guess the Hornady brass isn't very uniform. Glad I was able to get some new Lapua 6.5 Grendel brass to form ARC brass.

 

[Fret]

I recently ordered a 22" barrel from CLE. They had a choice of rifle, +1, and +2. I went with the +1. With all these cycling issues with long gas systems, maybe I should call them tomorrow and change to a regular rifle length gas system.

 

[LRJammer]

I recently ordered a 22" barrel from CLE. They had a choice of rifle, +1, and +2. I went with the +1. With all these cycling issues with long gas systems, maybe I should call them tomorrow and change to a regular rifle length gas system.

I ordered a 20" from them in rifle length. I have a 20" 5.56 with a rifle length that is amazingly soft shooting but absolutely reliable. I dont see the point in playing around with what works personally.

 

[TonyTheTiger]

What handguard length are y'all using with the +2 gas system? Will a 15"-15.5" cover at least the tube and part of the block or is longer necessary? I'd love to see pics of the handguard setups people are running with these +2 barrels.

15" will cover about half of the gas block on a +2. There's no rule that says the block must be covered, it's mostly aesthetic preference unless you really plan on using that end of your rifle to drive fence posts.

 

[Dino11]

Here are pictures of my two 18" barrel rifles, both of them have a 16.5" handguards. The line on the workbench is the front edge of the gas block. The Faxon barrel rifle is a standard rifle gas and the Odin is plus +2".

 

[TonyTheTiger]

Here are pictures of my two 18" barrel rifles, both of them have a 16.5" handguards. The line on the workbench is the front edge of the gas block. The Faxon barrel rifle is a standard rifle gas and the Odin is plus +2".

Faxon looks pretty mid length-ish from here.

 

[Dino11]

Faxon looks pretty mid length-ish from here.

You sir are correct, my mistake the 20 inch Faxon I have is rifle length.

 

[Southern Custom]

I'm surprised that Odin did not tell you about using the reduced power spring and lighting the buffer. I have one of their first barrels so I was on the front side of the 6ARC, as they were one of the first manufacture of the barrels. I got in before all the damn Pandemic hype going on and nobody could get anything because everybody wanted something all at the same time.

I called them and relayed the information on the fix as they had no information on what to do as they said that they only tested it with a carbine length buffer system and it worked fine for them. I also had to go through the 105 Black box ammo ordeal, I actually worked with Odin and Hornady to get this figured out. So I was very discouraged at first with the 6ARC, it was one problem right after another. Didn't you get an adjustable gas block and tube with your barrel?

Yup. The first block Odin sent leaked like a sieve. It was rattling on the barrel it was so oversized. The second one was tight on the barrel but still leaked from the front of the gas tube since the tube was a fairly loose fit and the front of the block at the gas tube is open on the Odin. As opposed to closed on the Aero. Also leaked a touch from the screw. I may weld up the front of the gas tube hole and run it later on but for now I’m sticking with the Aero since it’s finally running well.

 

[TonyTheTiger]

I know it sounds kinda redneck but every leaky gas block/tube I've had (10+) has been fixed by applying a little TFE pipe paste during assembly. I'm sure it's not mil-spec enough for the Timmy's here but it works.

 

[LRBuck]

Sounds like if it runs reliably, it might be ok. Mine will be suppressed pretty much all the time, so that might help.

When I ordered the Odin, I honestly thought it was a +1 gas system, not sure why, I must have confused the specs with the proof barrels I was looking at too. What handguard length are y'all using with the +2 gas system? Will a 15"-15.5" cover at least the tube and part of the block or is longer necessary? I'd love to see pics of the handguard setups people are running with these +2 barrels.

My +2 Craddock Rock Creek (22”) seems to run fine so far with a carbine buffer. I have no idea about the gas port size. I did tune the Superlative AGB. The aero 15” Quantum hand guard covers about 1/2 the gas block just like @Dino11’s.
Edit: just like @TonyTheTiger pic.

 

[alamo5000]

My +2 Craddock Rock Creek (22”) seems to run fine so far with a carbine buffer. I have no idea about the gas port size. I did tune the Superlative AGB. The aero 15” Quantum hand guard covers about 1/2 the gas block just like @Dino11’s.
Edit: just like @TonyTheTiger pic.

Quick question... what is the ID of your hand guard? And does that adjustable gas block have any problem fitting inside of there if it were required? I am assuming that is a .875 gas block btw.

 

[TonyTheTiger]

Should mention that all of my short stroking and near undergassed issues with a 22" +2 gas system happened while I was trying TAC and 8208. When I switched to CFE I was able to turn the gas down a bit and make this thing pretty soft shooting.

 

[LRBuck]

Quick question... what is the ID of your hand guard? And does that adjustable gas block have any problem fitting inside of there if it were required? I am assuming that is a .875 gas block btw.

Yes .875. No issue fitting but I wondered during install if it might be too close and touch with barrel whip. Non issue as far as I can tell. Shooting sub moa (mostly about .5) with everything so far.
I did not recall so checked on Aero site and they say the quantum is 1.78 inside diameter.

 

[Yondering]

I know it sounds kinda redneck but every leaky gas block/tube I've had (10+) has been fixed by applying a little TFE pipe paste during assembly. I'm sure it's not mil-spec enough for the Timmy's here but it works.

That’ll work. That “ultra black” RTV works in a similar way. My method isn’t for everyone, because it makes gas bocks harder to remove, but I use blue #243 Loctite, when installing the gas tube in the block and when installing the block on the barrel. In particular I smear some around the gas port and wet the inside of the block in the same area prior to installing. Then I put a healthy drop in each set screw hole before installing the screw; that forces the Loctite out between the block and barrel. Overkill, but that’s the point.

The situation with these Odin barrels and gas blocks sounds pretty underwhelming though. Besides the poor quality control and lack of adequate testing and gas system selection, there’s no reason to use an adjustable gas block with an undergassed barrel. An AGB can never provide more gas, only restrict what’s already available through the gas port.

I’ve never bought an Odin barrel but thought they were better than this prior to reading about these issues. That’s a real bummer for you guys who ended up with them.

 

[Yondering]

Should mention that all of my short stroking and near undergassed issues with a 22" +2 gas system happened while I was trying TAC and 8208. When I switched to CFE I was able to turn the gas down a bit and make this thing pretty soft shooting.

Yep, same reason I mentioned Lever earlier; it produces more gas than most other good powder choices (not just for the ARC but a host of AR15-sized cartridges) and will often cycle a barrel that is under gassed for everything else. (IMO Lever and CFE223 are very close in this regard.)

At the same time that’s why I avoided using it in 5.56 for a long time, because I found that when my rifles were tuned for 8208 or similar powders they’d be over gassed hard with Lever. I’ve now switched to using Lever exclusively for certain rifles so it’s no longer an issue, like in the 20” 5.56 I built recently that was under gassed with everything else.

 

[TonyTheTiger]

@Yondering yup I've done the same with blue loctite before also.
I know a few people that have had good luck with Odin barrels for 3 gun, but in more standard configurations, and in 223 obviously. They seem well made but apparently making a part well is entirely different than actually understanding what you're doing.
I just bought a pound of Lever based on all the success I've seen with it on here lately. I'm not displeased with CFE but I'm a sucker for trying new things. I even keep buying Nosler RDF's when they come out with new ones. Someday I'll learn.
How does Lever do in 223 loads?