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[ARCHIVED THREAD] - Overgassed BCM upper?

Posted: 10/16/2018 2:33:42 PM EDT

So I purchased a new ELW 11.5” upper from BCM and it functions great but seemed like some excessively strong recoil so I sought to reduce it by trying out different buffers and springs. It ended up still cycling prefectly using Hornady 75gr SBR ammo with a ST-T2 and a sprinco Orange spring (!). I tried the blue and red prior to that as well. This seems to indicate a massive overgassing to me. I also still plan to suppress this gun. Will an SLR sentry gas block fix the problem? I also installed an A5 buffer with a sprinco green spring and voltr standard buffer now.

Posted: 10/16/2018 4:14:36 PM EDT

[#1]

Quoted:
So I purchased a new ELW 11.5” upper from BCM and it functions great but seemed like some excessively strong recoil so I sought to reduce it by trying out different buffers and springs. It ended up still cycling prefectly using Hornady 75gr SBR ammo with a ST-T2 and a sprinco Orange spring (!). I tried the blue and red prior to that as well. This seems to indicate a massive overgassing to me. I also still plan to suppress this gun. Will an SLR sentry gas block fix the problem? I also installed an A5 buffer with a sprinco green spring and voltr standard buffer now.

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I don't have any advice on the gas block, etc for you, but I can confirm that my 11.5" BCM ELWF upper is the same way. I run an H2 and it's still a little more pop than I expected with it. I just (today) changed out the A2 flash hider for a Surefire Warcomp CTN. Going to shoot it tomorrow and see if there's any noticeable difference...

Posted: 10/16/2018 5:20:12 PM EDT

[#2]

I had a pair of 16" ELW uppers made last November and they were 1:00-1:30 ejecting gassers.

Posted: 10/16/2018 5:45:56 PM EDT

[#3]

both of my BCMs have a "healthy" ejection going on. one 12.5 and one 14.5

Posted: 10/16/2018 6:46:23 PM EDT

[#4]

Quoted:
So I purchased a new ELW 11.5" upper from BCM and it functions great but seemed like some excessively strong recoil so I sought to reduce it by trying out different buffers and springs. It ended up still cycling prefectly using Hornady 75gr SBR ammo with a ST-T2 and a sprinco Orange spring (!). I tried the blue and red prior to that as well. This seems to indicate a massive overgassing to me. I also still plan to suppress this gun. Will an SLR sentry gas block fix the problem? I also installed an A5 buffer with a sprinco green spring and voltr standard buffer now.

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Yes, adjustable gas will address the problem. I use SLRs on many of my suppressed guns, and it cuts down on recoil and gas to the face (esp since I'm a lefty).

Posted: 10/16/2018 7:07:26 PM EDT

[#5]

Quote History

Quoted:
Yes, adjustable gas will address the problem. I use SLRs on many of my suppressed guns, and it cuts down on recoil and gas to the face (esp since I'm a lefty).

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I have a couple SLRs, and they are awesome, but I’m concerned that they won’t be strong enough to handle the SBR with a suppressor without breaking?

Posted: 10/17/2018 9:45:04 AM EDT

[#6]

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Quoted:

I have a couple SLRs, and they are awesome, but I’m concerned that they won’t be strong enough to handle the SBR with a suppressor without breaking?

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If you are concerned with it breaking look into the Black River Tactical gas block inserts. No moving parts, they work very well and are durable

Posted: 10/17/2018 10:31:04 AM EDT

[#7]

Quote History

Quoted:

I have a couple SLRs, and they are awesome, but I'm concerned that they won't be strong enough to handle the SBR with a suppressor without breaking?

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I use an SLR on my 10.5" AR and it has been more than adequate. My only complaint is that it seizes up quick if you don't clean it fairly regularly. But it definitely holds up to the abuse.

Posted: 10/17/2018 10:32:50 AM EDT

[#8]

I use a Geissele Super 42 and Gemtech SBC with my 11.5" and Trek that works well enough to tame the gassing. Its not fine tune adjustable but works good enough for me.

Posted: 10/17/2018 11:46:02 AM EDT

[#9]

If you want to drop the carriers reaction to gas it can be done several ways.

Cutting down gas to lower the bolt's piston action can be accomplished by the following=
A gas port insert will shrink the port size and not allow as much gas to enter the block.
An adjustable gas block will lower the gas volume traveling through the block.
An adjustable gas tube or a gas tube insert will cut the amount of gas flowing through the tube.
An adjustable gas key or adjustable carrier will cut down gas volume delivered to the bolt.
A one piece gas ring with weep hole edging will allow gas to escape around the ring and lower the pressure on the ring.
These are all ways to limit the gas forces applied on the bolt.

Lowering the carriers reaction mechanically rather than cutting gas can be accomplished by the following=
Upping buffer spring weight will slow the carriers movement with added resistance.
Upping the buffer weight will help delay the carriers momentum.
Using a solid buffer vs. a floating weight buffer will slow the carriers initial movement and acceleration. Your A5 buffers internal buffer spring should already accomplish this.

Posted: 10/17/2018 3:41:44 PM EDT

[#10]

My 14.5 BFH with factory p/w Extended BCM Comp is so overgassed it gives me a headache while shooting WOLF CLASSIC! It is "extremely energetic" with NATO spec ammo. I've tried up to the H3 buffer, and no joy. Still rattles my brain.

Posted: 10/17/2018 7:42:16 PM EDT

[#11]

Guess I got lucky when I bought my ELW when they first came out

I cant even go one click on the Bootleg unsuppressed before it doesn't cycle. Works great on suppressed when running my suppressor.

Posted: 10/17/2018 7:44:35 PM EDT

[#12]

i had the same experience with a bcm barrel. i no longer buy their barrels. their other stuff is good.

Posted: 10/17/2018 8:21:57 PM EDT

[#13]

Superlative gas block are gtg

Posted: 10/17/2018 8:48:50 PM EDT

[#14]

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Quoted:
i had the same experience with a bcm barrel. i no longer buy their barrels. their other stuff is good.

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Like what?

Aside from the MCMR Handguards what do they have?

Posted: 10/17/2018 10:24:26 PM EDT

[#15]

Thanks for all the responses guys! Picked up a Sentry 6 today!

Posted: 10/17/2018 11:19:48 PM EDT

[#16]

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Quoted:

Like what?

Aside from the MCMR Handguards what do they have?

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Grips, stocks, endplates, charging handles, BCGs, muzzle brakes. Probably other stuff I'm forgetting.

Posted: 10/18/2018 1:07:45 AM EDT

[#17]

My 14.5 and 16 elw bcm uppers run smother then my 6920, they are very soft shooting. Shot my friends 11.5 elw pistol build it wasn’t bad at all. Don’t see what the issue is.

Posted: 10/19/2018 8:35:04 AM EDT

[#18]

Quote History

Quoted:
Like what?

Aside from the MCMR Handguards what do they have?

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Quote History

Quoted:

Quoted:
i had the same experience with a bcm barrel. i no longer buy their barrels. their other stuff is good.

Like what?

Aside from the MCMR Handguards what do they have?

Well those handguards are pretty sweet. I’m partial to their mod3 grips. And their stripped upper receivers are made to fit very tightly to the barrel extension, which I appreciate.

Posted: 10/19/2018 9:24:35 AM EDT

[#19]

Quote History

Quoted:
My 14.5 and 16 elw bcm uppers run smother then my 6920, they are very soft shooting. Shot my friends 11.5 elw pistol build it wasn’t bad at all. Don’t see what the issue is.

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I guess it's hit or miss. I have a few 6920 uppers and when I got the pair of 16" ELW upper last year I shot them side by side and the ELWs were noticeably harsher with very forward ejection. I put an VLTOR A5 kit behind 'em and I think it was worse.

I replaced 'em with 16" Daniel Defense barrels and they do right now.

Posted: 10/19/2018 10:19:50 AM EDT

[#20]

Quote History

Quoted:

Well those handguards are pretty sweet. I’m partial to their mod3 grips. And their stripped upper receivers are made to fit very tightly to the barrel extension, which I appreciate.

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It's a shame they had so many retarded people try to cover muzzle devices with the original magnesium handguards, forcing them to move to aluminum.

Yeah it's dickmod but I *LOVE* my original KMR.

Posted: 10/19/2018 11:18:30 AM EDT

[#21]

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Quoted:

It's a shame they had so many retarded people try to cover muzzle devices with the original magnesium handguards, forcing them to move to aluminum.

Yeah it's dickmod but I *LOVE* my original KMR.

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Finding an original was the hardest part to find for my rifle. Coupled with the titanium barrel nut and hardware its stupid light weight for 13 inches of metal.

Posted: 10/20/2018 2:13:47 PM EDT

[#22]

I bent an OG 13” KMR rail, the alpha series seems stronger to me.

Posted: 10/22/2018 2:12:34 PM EDT

[#23]

I put my SLR adjustable block on, dialed it in, and man it is a world of difference. I feel like I’m cheating now. Completely worth it.

On a side note, BCM does not mess around with their set screws in a gas block. Seriously had a hell of a time getting that thing off. Ended up having to cut it off. No joke.

Posted: 10/22/2018 11:35:06 PM EDT

[#24]

Quote History

None technical remark deleted.

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[ARCHIVED THREAD] - Overgassed BCM upper?

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