Carbon spray from between uppers?

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[ARCHIVED THREAD] - Carbon spray from between uppers?

Posted: 6/17/2019 8:17:59 PM EDT

Currently have a 13.9 build built on aero m4e1 upper and lower set. I suppress it a lot with a yhm turbo and use a bootleg ind adjustable bcg. The rifle is great except that there is a lot of carbon spraying out from between the upper and lower. Any thoughts on how to get rid of this? Thought about adding some paint there maybe?

Posted: 6/17/2019 10:40:53 PM EDT

[#1]

Keep it cleaner?

Other than that you could try a grease instead of oil maybe or an Accuwedge to tighten up the gap between your receivers.

Posted: 6/17/2019 10:49:18 PM EDT

[#2]

Sounds like you're running it wet if you're getting carbon spraying. In this case, I'd say too wet.

If you must run it like you do, but want to seal the upper to the lower, maybe try form-a-gasket or gluing rubber bands on the flat sections of the upper or lower, so they form a compression seal when the halves are together.

Posted: 6/18/2019 11:55:52 PM EDT

[#3]

Quote History

Quoted:
Keep it cleaner?

Other than that you could try a grease instead of oil maybe or an Accuwedge to tighten up the gap between your receivers.

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Accuwedge would push them apart.

Posted: 6/19/2019 12:37:52 AM EDT

[#4]

Quote History

Quoted:
Accuwedge would push them apart.

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Quoted:

Quoted:
Keep it cleaner?

Other than that you could try a grease instead of oil maybe or an Accuwedge to tighten up the gap between your receivers.

Accuwedge would push them apart.

I have to agree about the oil, but where exactly does the adjustable gas BCG vent or relieve it's regulated gas? Or does it? I have never seen one, but assumed it HAS to vent that gas somewhere else, since it is ALL coming down the gas tube from the gas block. Curious if that adds to the gas in the upper.

Posted: 6/19/2019 5:42:48 AM EDT

[#5]

Swap out the adjustable gas BCG for an adjustable gas block

Posted: 6/19/2019 10:53:19 AM EDT

[#6]

That's pretty normal when shooting suppressed. Nothing worth trying to fix.

this is after about 300 rounds suppressed.

i don't even bother cleaning that area up anymore.

Posted: 6/19/2019 11:16:54 AM EDT

[#7]

Is it causing any issues? Why do you think it needs fixed?

Posted: 6/19/2019 11:40:36 AM EDT

[#8]

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Quoted:

Accuwedge would push them apart.

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Well I'm 0 for 2 on advice today

Posted: 6/24/2019 2:15:38 PM EDT

[#9]

Quote History

Quoted:

I have to agree about the oil, but where exactly does the adjustable gas BCG vent or relieve it's regulated gas? Or does it? I have never seen one, but assumed it HAS to vent that gas somewhere else, since it is ALL coming down the gas tube from the gas block. Curious if that adds to the gas in the upper.

View Quote

Its the bootleg ind version. It has more vents on the ejection port side and a valve that can be set to different levels of gas. My concern is the stuff leaking feom the left side and getting in my mouth and shit. I dont like ingesting lead.

Posted: 6/24/2019 2:16:23 PM EDT

[#10]

Quote History

Quoted:
Swap out the adjustable gas BCG for an adjustable gas block

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I dont like adjustable gas blocks as the require a tool and also are a pain to get to with my handguard and mawl

Posted: 6/24/2019 2:17:12 PM EDT

[#11]

Quote History

Quoted:
That's pretty normal when shooting suppressed. Nothing worth trying to fix.

this is after about 300 rounds suppressed.

i don't even bother cleaning that area up anymore.

https://i.ibb.co/RvMhkf5/790929-C4-4499-4641-8-A52-DDDCE01988-DE.jpg

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Its worse than that at 300 and i shoot usually between 600 -1000 a session

Posted: 6/24/2019 2:17:55 PM EDT

[#12]

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Quoted:
Is it causing any issues? Why do you think it needs fixed?

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Its getting all over my face and in my mouth and id rather not have that.

Posted: 6/24/2019 2:38:36 PM EDT

[#13]

Normal, depending on powder, especially if you run wet.

Posted: 6/24/2019 2:40:38 PM EDT

[#14]

Quote History

Quoted:
I dont like adjustable gas blocks as the require a tool and also are a pain to get to with my handguard and mawl

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You shouldn't have to get to it after it's set.

Same with adjustable gas keys. Set it to just lock back unsuppressed and it will have less blowback suppressed.

Have you actually dialed in your adjustable key?

Posted: 6/24/2019 3:11:08 PM EDT

[#15]

Quote History

Quoted:

You shouldn't have to get to it after it's set.

Same with adjustable gas keys. Set it to just lock back unsuppressed and it will have less blowback suppressed.

Have you actually dialed in your adjustable key?

View Quote

Yup, switch it till it barely cycles on suppressed

Posted: 6/24/2019 4:00:32 PM EDT

[#16]

Electrical tape, it's black and will blend in easily. Unless your AR is not black.

Posted: 6/25/2019 5:41:08 AM EDT

[#17]

Quote History

Quoted:

Its the bootleg ind version. It has more vents on the ejection port side and a valve that can be set to different levels of gas. My concern is the stuff leaking feom the left side and getting in my mouth and shit. I dont like ingesting lead.

View Quote

I understand, trust me. Don't run it dripping wet, that truly makes it worse. I had some ammo/powders that were worse than others, too. I had a case of Independence blue box that was just gnarly.

Still, even my most overgassed SBR upper did not seem to be quite as bad as you are experiencing, which is why I come back to the oil

Posted: 6/25/2019 1:08:02 PM EDT

[#18]

You might try switching to grease as your lubricant - less chance of spray and migration into areas you don't want it.

Posted: 6/25/2019 1:24:40 PM EDT

[#19]

It would probably work better if you were running an upper and a lower instead of more than one upper as indicated in your title.

Posted: 6/25/2019 6:55:45 PM EDT

[#20]

Does electrical tape work? Seems like the easies solution

Posted: 6/25/2019 7:00:47 PM EDT

[#21]

Quote History

Quoted:
You might try switching to grease as your lubricant - less chance of spray and migration into areas you don't want it.

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This is IMO the best answer I've seen yet.

Of course, you could just keep firing it until that gap is plugged up with carbon. That's the method @brodband8 uses.

Posted: 6/25/2019 7:17:17 PM EDT

[#22]

I just keep mine lubed with mobil 1. It gets kind of dirty sometimes but it continues to work. Most of the blowback ends up on my support arm or cheek but thats about it.

Attached File

Posted: 6/25/2019 7:29:46 PM EDT

[#23]

Your symptoms sound pretty normal. This is only 1000.

Attached File

Posted: 8/9/2019 9:15:05 AM EDT

[#24]

So ive started to just put a peice of duct tape on that side and it helps a lot though not very pretty haha

Im thinking about possibly trying the new Strike Industries gas block but not sure if i wanna give up my G. Its already pinned in place. The other thing is I could spring for something a little higher end receiver set wise

Posted: 8/9/2019 10:24:02 AM EDT

[#25]

I run corrosive surplus 7.62x39 & 5.45x39 thru several AR uppers and the spray is pretty oily, used to get all over my shooting glasses til I put a gas lip on the charge handle.

there's plenty of info on how to do that, just takes a bit of RTV silicon. or buy an aftermarket handle with a gas lip like the GasBuster or the Geissele. I run a Geissele on the 7.62x39 and it works fine, although the silicon lip makes a better seal even if it looks home made.

I also pulled the forward assists from both uppers to let the excess gas vent. There's an aftermarket gizmo that's a cap the replaces the FA for venting or you can make one with a .45acp casing but I just prefer to run it wide open. If you're not blowing gas from the charge handle you probably won't notice it anywhere else, unless you've just got excess oil coming from between the upper & lower, which just means too much oil. But that has nothing to do with excessive back pressure, that's just the carrier slinging oil.

[ARCHIVED THREAD] - Carbon spray from between uppers?

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