Bear Creek AR-10, 22-250

[Dewey Johnskn]

24 inch barrel, 1:14 twist. 0.750 gas block, rifle length gas block system. Ejected brass lands 3-5 oclock, not stained from over gassing. Watched the bolt in slow mo when fired and it doesnt come back far enough to pick up next round or lock back on empty mag. Plenty of lube and smooth cycling when hand cycling rounds

[jtallen83]

Have you checked gas block alignment? Where does the gas tube end in the receiver, the middle of the cam pin cutout? What do you have for a buffer system? Buffer weight and bad springs play a role in many that don't run. You might want to measure the gas port size when you check gas block alignment, could be a small port. Someone should be along shortly with a more defined approach, search out the "waterboarding" thread for a list of required details for that troubleshooting process.

[Dewey Johnskn]

39 minutes ago, jtallen83 said:

Have you checked gas block alignment? Where does the gas tube end in the receiver, the middle of the cam pin cutout? What do you have for a buffer system? Buffer weight and bad springs play a role in many that don't run. You might want to measure the gas port size when you check gas block alignment, could be a small port. Someone should be along shortly with a more defined approach, search out the "waterboarding" thread for a list of required details for that troubleshooting process.

I can get all that info for you when i get off work. Thanks

[98Z5V]

14 hours ago, Dewey Johnskn said:

Watched the bolt in slow mo when fired and it doesnt come back far enough to pick up next round or lock back on empty mag.

Describe your recoil system, in great detail.  That's number 1 here, that needs ruled out, based on what you stated.  I think you have the wrong buffer in here, based on words.  Need to confirm that you're running.

[98Z5V]

Was this a complete gun from BCA?  A complete upper, only?  What are we looking at here, and if it's not all factory parts, list everything you did to build the rest of it out.  Thanks in advance.

[Dewey Johnskn]

9 hours ago, 98Z5V said:

Was this a complete gun from BCA?  A complete upper, only?  What are we looking at here, and if it's not all factory parts, list everything you did to build the rest of it out.  Thanks in advance.

Its a complete BCA upper. Then a few weeks later i bought BCA’s AR10 Lower. Buffer spring is 11 inches long, 32 coils, buffer is 2.5 inches long, i have no way of getting the weight for you, but it has an orange tip and 2 black tungsten weights in it that i took out with no effect. Buffer tube is 15/16.

[Dewey Johnskn]

Video of short stroke. Not the greatest i kno but if u look closely youll see the bolt needed to come back 1/4-1/2 inch more to pick up the next round.

[Dewey Johnskn]

Gas tube sticks into the upper just shy of 1 inch. Hard to get an exact measurement.

[Matt.Cross]

On 2/10/2023 at 8:55 AM, Dewey Johnskn said:

Gas tube sticks into the upper just shy of 1 inch. Hard to get an exact measurement.

That's a great photo, your gas tube is well shy of the center of the cam pin relief cut.

[Dewey Johnskn]

6 minutes ago, Matt.Cross said:

That's a great photo, your gas tube is well shy of the center of the cam pin relief cut.

My first AR-10 so thats why im asking before just replacing. I know with AR-15’s you want the gas tube about 2/3 into the relief cut. Think we may of found the problem?

[Matt.Cross]

On 2/10/2023 at 9:21 AM, Dewey Johnskn said:

My first AR-10 so thats why im asking before just replacing. I know with AR-15’s you want the gas tube about 2/3 into the relief cut. Think we may of found the problem?

I don't know that your issue has a single cause, but I DO know that you've found and can correct a significant issue. When you have the right length gas tube, it'll end at or very near to the center of that cutout.

[Dewey Johnskn]

Update: gas port was undersized. It was .065. Drilled out to .075, still short stroke. Drilled it out to .08 and it runs flawlessly now.

[NF1E]

Well done.

[98Z5V]

9 hours ago, Dewey Johnskn said:

Update: gas port was undersized. It was .065. Drilled out to .075, still short stroke. Drilled it out to .08 and it runs flawlessly now.

Well done - but I'd get rid of that gas tube anyway.  It's short - gas tubes should end directly in the center of the cam pin cutout, in a perfect world. 

You may have adjust a gas port for a recoil system problem.  Your recoil system specs for a Large Frame are way off.

14 hours ago, Dewey Johnskn said:

Its a complete BCA upper. Then a few weeks later i bought BCA’s AR10 Lower. Buffer spring is 11 inches long, 32 coils, buffer is 2.5 inches long, i have no way of getting the weight for you, but it has an orange tip and 2 black tungsten weights in it that i took out with no effect. Buffer tube is 15/16.

Recoil spring is way off - not even a proper spring for the M4.  Let alone a Large Frame.  Your buffer weighs 3.8oz, just by your description, and it has an aluminum body.  Only way to get a 2.500" buffer close to the necessary 5.4oz is if it uses a stainless steel body, and those same two tungsten weights in it.  Buffer needs to weight 5.4oz, or pretty damn close, for a proper recoil system in these big things. 

You're obviously using the AR15 carbine receiver extension, which is 7.000" internal depth, or you wouldn't be running a 2.500" buffer without damage to the gun.  Perfect would be Armalite's spec at 6 15/16" internal depth, but nobody in the aftermarket follows that, at all, and they make them 7.000" internal.  No big deal, they all work.

The proper spring for that setup - there's only one - is the Sprinco Orange spring - with the correct buffer weight, in the (very close) 5.4oz range.

If it runs, it runs.  If you want to fix it the recoil system to make it more reliable, you might be drilling that gas port up again.  I think my gas port calculations for this setup - with a proper recoil system - were higher than 0.080". 

Just my $0.02 on it all. 

 

[Armed Eye Doc]

21 hours ago, Dewey Johnskn said:

Update: gas port was undersized. It was .065. Drilled out to .075, still short stroke. Drilled it out to .08 and it runs flawlessly now.

Nice job!  If you have not already, I would test it with multiple ammo varieties to check for reliability across different ammo loads.  If it eats it all, you have finished the job.  If you start having problems with weaker or hotter loads, then implement 98's suggestions above.

There's nothing wrong with a rifle that functions exceptionally with a specific round until you can't get that round.  I, and most others on the forum, prefer to have a rifle that may prefer a certain round but will function well with anything available.

Edited February 11, 2023 by Armed Eye Doc

[shooterrex]

Yep that recoil system is not up to the job.

This buffer and a springco orange spring should fix your recoil system.

https://www.kakindustry.com/lr308-carbine-buffer-heavy

[Dewey Johnskn]

On 2/10/2023 at 10:31 PM, 98Z5V said:

Well done - but I'd get rid of that gas tube anyway.  It's short - gas tubes should end directly in the center of the cam pin cutout, in a perfect world. 

You may have adjust a gas port for a recoil system problem.  Your recoil system specs for a Large Frame are way off.

Recoil spring is way off - not even a proper spring for the M4.  Let alone a Large Frame.  Your buffer weighs 3.8oz, just by your description, and it has an aluminum body.  Only way to get a 2.500" buffer close to the necessary 5.4oz is if it uses a stainless steel body, and those same two tungsten weights in it.  Buffer needs to weight 5.4oz, or pretty damn close, for a proper recoil system in these big things. 

You're obviously using the AR15 carbine receiver extension, which is 7.000" internal depth, or you wouldn't be running a 2.500" buffer without damage to the gun.  Perfect would be Armalite's spec at 6 15/16" internal depth, but nobody in the aftermarket follows that, at all, and they make them 7.000" internal.  No big deal, they all work.

The proper spring for that setup - there's only one - is the Sprinco Orange spring - with the correct buffer weight, in the (very close) 5.4oz range.

If it runs, it runs.  If you want to fix it the recoil system to make it more reliable, you might be drilling that gas port up again.  I think my gas port calculations for this setup - with a proper recoil system - were higher than 0.080". 

Just my $0.02 on it all. 

 

Definitely want this rifle built 100% correct for any and all situations. Thank you for all this information. I will convert to your suggested recoil system and gas tube over next couple weeks and also experiment with lighter rounds as im shootin the heaviest bullet my barrel will stabilize now at 50 gr.

Your $0.02 was worth every penny😂

Edited February 14, 2023 by Dewey Johnskn

[98Z5V]

1 hour ago, Dewey Johnskn said:

Your $0.02 was worth every penny😂

I'm here for you, every step of the way.  It's mechanical, so it can't out-think us.  

[Dewey Johnskn]

With my 24 inch barrel rifle length gas system, what length gas tube should i get? Any rifle length gas tube?

[shooterrex]

It needs to be about 1/4" longer than the one you have now.

[98Z5V]

15 hours ago, Dewey Johnskn said:

With my 24 inch barrel rifle length gas system, what length gas tube should i get? Any rifle length gas tube?

It obviously shipped with an AR15 Rifle Gas Tube in it, or the pic you posted before wouldn't look like it did.  You need an Armalite AR-10 Rifle Length Gas Tube to make that right.

Not a copy, not a description of "AR-10 Rifle gas tube" from some shiit-vendor - the real part, from Armalite.  Armalite Part # is 10007010. It's 15.5" OAL, and that's what you need to solve this issue.

[Dewey Johnskn]

11 hours ago, 98Z5V said:

It obviously shipped with an AR15 Rifle Gas Tube in it, or the pic you posted before wouldn't look like it did.  You need an Armalite AR-10 Rifle Length Gas Tube to make that right.

Not a copy, not a description of "AR-10 Rifle gas tube" from some shiit-vendor - the real part, from Armalite.  Armalite Part # is 10007010. It's 15.5" OAL, and that's what you need to solve this issue.

Where can I find it in stock?

[shooterrex]

If you can't find the Armalite part. These people will make you one the right size.

https://www.whiteoakarmament.com/gas-tube-extended-length-2.html

[98Z5V]

11 hours ago, Dewey Johnskn said:

Where can I find it in stock?

Rex is exactly right, below.   vvv

11 hours ago, shooterrex said:

If you can't find the Armalite part. These people will make you one the right size.

https://www.whiteoakarmament.com/gas-tube-extended-length-2.html

White Oak Armament will make you any gas tube you want, whenever you want, and you can do it right on their website - in the past, you used to have to call it in, and be questioned on what you were doing, what you were making, why you think it's correct - and they stopped that, with a disclaimer.  They're gonna make anything you want, you specify it, and it's not their issue if it doesn't work out. They make it to your dimensions, that you specify.

You click this link right here, and it's the page to get your custom gas tube from WOA.

https://www.whiteoakarmament.com/white-oak-custom-gas-tube.html

What the Armalite Rifle gas tube is:  15.5" OAL, AR-10 bend.  You order that, and you'll get a gas tube that's identical to one you'd get from Armalite.  If you want to measure and get specific, find out how far your gas tube is from center of the cam pin cutout, remove your gas tube and measure it's OAL, and add the dimension that's "short from center." That will give you a perfect gas tube, that ends in the very center of the cam pin cutout, like it should be. 

Your barrel was drilled "in between."  It's gas port location isn't AR15, and it's not Armalite AR-10.  It's between those two specs.

[Dewey Johnskn]

23 hours ago, 98Z5V said:

Rex is exactly right, below.   vvv

White Oak Armament will make you any gas tube you want, whenever you want, and you can do it right on their website - in the past, you used to have to call it in, and be questioned on what you were doing, what you were making, why you think it's correct - and they stopped that, with a disclaimer.  They're gonna make anything you want, you specify it, and it's not their issue if it doesn't work out. They make it to your dimensions, that you specify.

You click this link right here, and it's the page to get your custom gas tube from WOA.

https://www.whiteoakarmament.com/white-oak-custom-gas-tube.html

What the Armalite Rifle gas tube is:  15.5" OAL, AR-10 bend.  You order that, and you'll get a gas tube that's identical to one you'd get from Armalite.  If you want to measure and get specific, find out how far your gas tube is from center of the cam pin cutout, remove your gas tube and measure it's OAL, and add the dimension that's "short from center." That will give you a perfect gas tube, that ends in the very center of the cam pin cutout, like it should be. 

Your barrel was drilled "in between."  It's gas port location isn't AR15, and it's not Armalite AR-10.  It's between those two specs.

The only Armalite AR-10 gas tube i could find was on PrimaryArms website and the reviews said it was 15” and not 15.5”. I found a 15.5” AR-10 gas tube on Wilson Combat’s site and ordered it. If it doesnt fit ill send it back and hook up with White Oak on a tube. Buffer weight and spring should be here this weekend as well.