Low mass bolt carrier for 6mm CM, opinions and advice?

[Big Moose]

I'm running a 6mm CM gas-gun with a standard weight bolt carrier, it has an adjustable gas-block, and a rifle +2 inch gas system. I have the gas system opened up completely to make the bolt cycle, and as a result I'm getting a lot of back fouling and fouling around the gas block on the barrel. I'm thinking I could run this more efficiently with a low mass bolt carrier, which would allow me to turn the gas dial back. Any thoughts? Thanks.

 

[flyer]

Sounds like your gas block doesn't fit well on the journal.

If you are running it wide open, just get a standard gas block to replace it. Maybe a clamp on style to reduce the gas leak.

 

[Big Moose]

Sounds like your gas block doesn't fit well on the journal.

If you are running it wide open, just get a standard gas block to replace it. Maybe a clamp on style to reduce the gas leak.

Thanks it's a GA built gun, which they built for me on MA TEN receiver set. The block is the same they use on their GAP 10 builds.

 

[Ranger188]

Moose, JP makes some low mass carriers.
Who knows if it will work for you.

JP - Low Mass Operating System

 

[Big Moose]

Moose, JP makes some low mass carriers.
Who knows if it will work for you.

JP - Low Mass Operating System

Thanks I run their carriers in all my other ARs, wasn't sure about the implications in large frame though.

 

[lash]

Or a JP Silent Captured Spring System. That worked for me with a full mass BCG and +2 gas on a 22” .224V.

 

[Big Moose]

Or a JP Silent Captured Spring System. That worked for me with a full mass BCG and +2 gas on a 22” .224V.

Thanks, I'll call JP for their input.

 

[Ranger188]

Moose, another option, I run these in my AR15's really nice

308 National Match Carrier Complete w/ Forward Assist (Chrome only) - Young Manufacturing, Inc.

Like our signature 5.56mm carrier the .308 version has added surface area in the front of the carrier gives a tighter fit when the bolt is in battery for more

youngmanufacturing.net

It doesn't cost anything to call and see if these options might work for you,

 

[Big Moose]

Moose, another option, I run these in my AR15's really nice

308 National Match Carrier Complete w/ Forward Assist (Chrome only) - Young Manufacturing, Inc.

Like our signature 5.56mm carrier the .308 version has added surface area in the front of the carrier gives a tighter fit when the bolt is in battery for more

youngmanufacturing.net

It doesn't cost anything to call and see if these options might work for you,

Thanks for your input dude.

 

[Yondering]

Assuming the gas block is already aligned right, I'd start with sealing the gas block to the barrel to eliminate that leakage. You can wipe a little bit of black or copper RTV or blue Loctite around the gas port hole and inside the gas block and re-install it; this seals it and stops the leakage you're seeing. Of course, don't use so much that you block the hole, a very thin wipe is all it takes.

On the lightweight carriers - I don't have a 6 Cm, but use a light weight carrier on my 308 and really like it. My carrier is right about the same weight as a full auto AR15 carrier and in my experience it makes the gun a bit easier to shoot well. Something like that may solve your under-gas issues, but try just sealing the gas block first.

 

[Big Moose]

Assuming the gas block is already aligned right, I'd start with sealing the gas block to the barrel to eliminate that leakage. You can wipe a little bit of black or copper RTV or blue Loctite around the gas port hole and inside the gas block and re-install it; this seals it and stops the leakage you're seeing. Of course, don't use so much that you block the hole, a very thin wipe is all it takes.

On the lightweight carriers - I don't have a 6 Cm, but use a light weight carrier on my 308 and really like it. My carrier is right about the same weight as a full auto AR15 carrier and in my experience it makes the gun a bit easier to shoot well. Something like that may solve your under-gas issues, but try just sealing the gas block first.

Many thanks

 

[bigjake83]

Assuming the gas block is already aligned right, I'd start with sealing the gas block to the barrel to eliminate that leakage. You can wipe a little bit of black or copper RTV or blue Loctite around the gas port hole and inside the gas block and re-install it; this seals it and stops the leakage you're seeing. Of course, don't use so much that you block the hole, a very thin wipe is all it takes.

On the lightweight carriers - I don't have a 6 Cm, but use a light weight carrier on my 308 and really like it. My carrier is right about the same weight as a full auto AR15 carrier and in my experience it makes the gun a bit easier to shoot well. Something like that may solve your under-gas issues, but try just sealing the gas block first.

Yondering, I'm not trying to shit on your advice but using silicone or loctite is not the proper way to seal a gas block, those methods have the propensity to easily go into Barrel and Gas Block gas ports.

You should always use a Hi Temp spray-on adhesive. I tape my barrels up with blue 3M to eliminate any overspray and cover the gas port on the barrel with the end of a Q-tip and make one even spray that covers about 50% of the top barrel circumference. Just make sure to pre-install your gas block/tube and make some alignment marks. it honestly doesn't take very much of this stuff you could really just spray some onto a sheet of paper and just apply with a Q-tip to the area around your gas Port of your barrel, I'm sure it would be sufficient.

 

[bigjake83]

I'm running a 6mm CM gas-gun with a standard weight bolt carrier, it has an adjustable gas-block, and a rifle +2 inch gas system. I have the gas system opened up completely to make the bolt cycle, and as a result I'm getting a lot of back fouling and fouling around the gas block on the barrel. I'm thinking I could run this more efficiently with a low mass bolt carrier, which would allow me to turn the gas dial back. Any thoughts? Thanks.

OP, are you ssying that you need the gas wide open just to make it cycle and it will not cycle if you were to adjust it down just a little??

In regards to a low-mass operating system it could help, just basic physics the gas would now have less Mass to propel rearward over a standard size BCG, not only that but the low mass bcg's smooth out the the recoil impulse as well.

I would first remove your gas block and measure the gas port in your Barrel, if your barrel port size is correct then I would carefully reinstall the gas block make sure to seal it as stated above.

Also you did not state whether you were running this system suppressed or not???

 

[Big Moose]

OP, are you ssying that you need the gas wide open just to make it cycle and it will not cycle if you were to adjust it down just a little??

In regards to a low-mass operating system it could help, just basic physics the gas would now have less Mass to propel rearward over a standard size BCG, not only that but the low mass bcg's smooth out the the recoil impulse as well.

I would first remove your gas block and measure the gas port in your Barrel, if your barrel port size is correct then I would carefully reinstall the gas block make sure to seal it as stated above.

Also you did not state whether you were running this system suppressed or not???

Thanks for your comments. I am planning to run it suppressed some of the time.

 

[Yondering]

Yondering, I'm not trying to shit on your advice but using silicone or loctite is not the proper way to seal a gas block, those methods have the propensity to easily go into Barrel and Gas Block gas ports.

You should always use a Hi Temp spray-on adhesive. I tape my barrels up with blue 3M to eliminate any overspray and cover the gas port on the barrel with the end of a Q-tip and make one even spray that covers about 50% of the top barrel circumference. Just make sure to pre-install your gas block/tube and make some alignment marks. it honestly doesn't take very much of this stuff you could really just spray some onto a sheet of paper and just apply with a Q-tip to the area around your gas Port of your barrel, I'm sure it would be sufficient.

The spray on adhesive may work fine as well, but personal experience on a bunch of different barrels shows that both Loctite and RTV work. Loctite (being anaerobic) has less potential to cause issues than your spray on adhesive, and if you use a very light swipe of RTV as I described, it works great too.

 

[1jonathan1994]

You probably need less spring. Get a scs with the weakest spring.