New 6.5 CM build gas issues

[NCHillbilly]

Well fellas, here's this weeks gas related question. I took out a new build for the first time today, to break-in the barrel and sign-in the scope.

The rifle is a ground up build. It consists of:
Noreen upper and lower receivers
x-caliber 6.5 CM 24", 1-8tw, +2 gas
superlative arms agb
KVP 5.6 oz. buffer and spring
Toolcraft bcg
RCA bolt

Here's the issue. It functions perfectly. Loads, ejects, locks back, and is very accurate. My issue is that currently, my ejection pattern is at about 2 o'clock, and that is with the block adjusted all the way out, in bleed-off mode. When I finally put the muffler on it, it will REALLY be overgassed.

I'm not sure that the agb is functioning properly. I never could get the bolt to NOT work. I tried shuuting all the gas off (but only in bleed-off mode), and with the screw all the way out, the bolt functioned perfectly. I don't mind trying different buffers or springs, but if it is a gas block issue, that needs to be addressed first. I am waiting to hear what SA suggests, but I thought I would bring it before Hide nation to see if anyone else had experienced this.

BTW, the barrel had been drilled for an agb at the factory, but I do not know the diameter of the gas port, I just know they specifically ask if an agb will be used, so I assume it is oversized to some degree.

 

[Clayman]

You haven't tried it in restricted?

 

[wade2big]

Stop using bleed off mode and use it like a regular adjustable gas block. When you finally put that muffler on it, you may very well have feeding issues from overgassing if you don’t.

 

[NCHillbilly]

You haven't tried it in restricted?

No, I did not. I did not take much more ammo than I needed to break in the barrel. I've got other loads ready to go, and may do just that before replacing anything.

 

[TonyTheTiger]

To look at this from a different angle, are you sure it is overgassed? Ejection angle is not the end all be all indicator of rifle health, and once you stray from mil spec it may mean nothing. You're not shooting the cartridge the ejection angle dogma was built around. The case you're ejecting is twice the size, weight and a different shape. You're not using a standard upper with a standardized shape/location of brass deflector. The BCG and it's extractor/ejector/springs are not standard.
It's a loose rule of thumb at best.

All that said, you should be able to shut the gas off completely in restriction mode.
I still haven't figured out the hype around the bleed off feature.

 

[celltech]

Had an Odin Works AGB on my first AR-10 6.5 build and even when all the way closed it still cycled. Odin said it was not meant for high pressure rounds. Put an SA block on and when fully turned off in restrictive mode it will hold shut...so try that for sure.

 

[NCHillbilly]

To look at this from a different angle, are you sure it is overgassed? Ejection angle is not the end all be all indicator of rifle health, and once you stray from mil spec it may mean nothing. You're not shooting the cartridge the ejection angle dogma was built around. The case you're ejecting is twice the size, weight and a different shape. You're not using a standard upper with a standardized shape/location of brass deflector. The BCG and it's extractor/ejector/springs are not standard.
It's a loose rule of thumb at best.

All that said, you should be able to shut the gas off completely in restriction mode.
I still haven't figured out the hype around the bleed off feature.

Everything you said is absolutely spot on. This rifle is an amalgamation of quality parts from numerous manufacturers. The ejection pattern thing is just a fast and loose kind of indicator for gas system performance.

When I started breaking in the barrel, I had the block set to open, no bleed-off or restriction. After a few rounds, I started adjusting it (in bleed off mode), and finally opened it as far as it would go, with no discernible difference.

The rifle performs tremendous, and has from the first round fired. Feeds, fires, ejects, locks open, and is very accurate, but I intend on suppressing this thing, and know if I am over gassed now, it'll just get worse.

One thing I did fail to mention earlier, is that I am getting some burrs on the rim of my extracted cases, like they might be getting yanked from the chamber too soon, which may point to the same issue.

My understanding is the bleed-off feature is to keep some of that gas out of the shooters face.

 

[bigjake83]

.
I still haven't figured out the hype around the bleed off feature.

I have superlative arms on most of my rifles but I have also gone back to restrictive mode and started buying the more basic adjustable gas blocks again for that very reason.

If you get a chance gives this one a go it has a super low profile, most AGBs carbon lock after a few hundred rounds as you know and I have yet to have one of these lock up or get stiff on me, the detents stay strong and tactile and the clicker is adjustable too

I just wish they made one in .875

 

[Sogan]

I have superlative arms on most of my rifles but I have also gone back to restrictive mode and started buying the more basic adjustable gas blocks again for that very reason.

If you get a chance gives this one a go it has a super low profile, most AGBs carbon lock after a few hundred rounds as you know and I have yet to have one of these lock up or get stiff on me, the detents stay strong and tactile and the clicker is adjustable too

I just wish they made one in .875
View attachment 8040770

Damn, those are priced really well too.

 

[TonyTheTiger]

@bigjake83 I'll keep those in mind next time I'm in the market. I didn't know FM was making an AGB but all of their other products I've seen have been fairly well thought out and very reasonably priced.

 

[NCHillbilly]

I have superlative arms on most of my rifles but I have also gone back to restrictive mode and started buying the more basic adjustable gas blocks again for that very reason.

If you get a chance gives this one a go it has a super low profile, most AGBs carbon lock after a few hundred rounds as you know and I have yet to have one of these lock up or get stiff on me, the detents stay strong and tactile and the clicker is adjustable too

I just wish they made one in .875
View attachment 8040770

Do you know if the use of these blocks require custom bent gas tubes, as is recommended for the SA blocks?

 

[bigjake83]

Do you know if the use of these blocks require custom bent gas tubes, as is recommended for the SA blocks?

I've never had to use any special non-standard gas tube with either of those adjustable gas blocks.

 

[bfoosh006]

Do you know if the use of these blocks require custom bent gas tubes, as is recommended for the SA blocks?

I have never read about a custom bent gas tube for the SA GB's... do you have a link ? ( not doubting you, just never seen that )

 

[NCHillbilly]

I've never had to use any special non-standard gas tube with either of those adjustable gas blocks.

Outstanding! I've got another barrel on order and need all the goodies to go with it, and I think I'll give one of those blocks a try.

It's info like this that keeps me coming to the hide. Much thanks.

 

[NCHillbilly]

I have never read about a custom bent gas tube for the SA GB's... do you have a link ? ( not doubting you, just never seen that )

It's on white oak's website. The barrel mfg ( x-caliber) suggested them for the gas tube, and they specifically call out the SA blocks as needing a special shape to maintain the correct fit in the upper receiver and gas key.

 

[NCHillbilly]

I have never read about a custom bent gas tube for the SA GB's... do you have a link ? ( not doubting you, just never seen that )

Superlative Arms Adjustable Gas Blocks

Superlative Arms Adjustable Gas Blocks

www.whiteoakarmament.com

Judt scroll down under the SA block description.

 

[bfoosh006]

Superlative Arms Adjustable Gas Blocks

Superlative Arms Adjustable Gas Blocks

www.whiteoakarmament.com

Judt scroll down under the SA block description.

Ironically, I've never noticed about the height differences because the larger barrel nut of the Large Frame AR makes up the differences.