Low profile adjustable gas blocks

[Hollywood 6mm]

Several years ago, I bit the bullet and built my first SBR. A couple weeks ago, I finally got to bring home my first center fire can. While my SBR runs beautifully without the can, it is horribly over-gassed with the can installed.

Here's the current configuration:

LMT 10.5" SBR/Pistol upper (1/7 chrome lined barrel)
DD Mk. 18 RIS II rail
AAC Brakeout compensator
AAC 7.62 SDN-6 can
Standard carbine recoil spring
H2 buffer

Without the can, I get consistent ejection between 3 and 4 o'clock, with brass being launched 25-25 feet. With the can installed, the ejection shifts to 1:00 to 1:30, and about 4 feet. Obviously the extra back pressure from the can is over-gassing the crap out of the gun.

I want to try replacing my current low profile gas block with an adjustable unit so I can tune the gas to reduce the beating my BCG is taking, but be able to open it up if needed to run unsuppressed without issues. Normally my answer would just be a Noveske Switchblock, but it will not fit under the Mk. 18 rail in any way that would allow it to function normally. I am also not willing (yet) to rebuild the upper or replace it with a Noveske barrel, Switchblock and rail. Has anyone worked with any low profile adjustable blocks worth a damn? Preferably one that adjusts from the front somehow where it would be easier to reach.

 

[RTH1800]

I have used a Seekins AGB. I do think it adjust from the rear IIRC.
JP makes a good one as well, but not sure low profile unit.

 

[fireEMT5]

Just put a SLR rifleworks low profile gas block on my AR. This unit adjusts from the front without the need to loctite or tighten a set screw, however you may need to also buy the long handle allen wrench from them to reach your block. Just my opinion, but after installing and using it, I won't be looking anywhere else. The customer service was top shelf. The block itself is very easy to tune/adjust and it works great.Gas Blocks

 

[Pat M]

for 1/2 the price get an adjustable gas tube, MGI Adjustable Gas Tube AR-15

 

[Hollywood 6mm]

Just put a SLR rifleworks low profile gas block on my AR. This unit adjusts from the front without the need to loctite or tighten a set screw, however you may need to also buy the long handle allen wrench from them to reach your block. Just my opinion, but after installing and using it, I won't be looking anywhere else. The customer service was top shelf. The block itself is very easy to tune/adjust and it works great.Gas Blocks

The SLR block, along with the JP/Syrac block look like the leading candidates right now. The SYrac uses a detent to give you locking positions every 90 degrees of turn, which would make it easy for me to switch between suppressed and unsuppressed gas levels.

for 1/2 the price get an adjustable gas tube, MGI Adjustable Gas Tube AR-15

Unfortunately, it looks like the adjustment screw faces straight up, meaning I wouldn't be able to make adjustments without removing my rail.

 

[fireEMT5]

The SLR also uses a detent and the adustment screw faces the muzzle, so it's easy to get a long allen or ball allen in there for adjustment. They are also located in FL. Give them a call, they'll answer all your questions.

 

[Ben Dover]

SLR has worked well on all my rifles.

 

[Hollywood 6mm]

I missed the detent feature the first time I read the info on the SLR.

Looks like we have a winner. Thanks for the assist, gents.

 

[FNARSHOOTER]

Govnah from Micromia 3 or 2 position fits under hand guard . can/off/no can or can/no can tool less adjustment. easy replacement plates .order the plates with undersized holes drill hole till it locks back with your load no can install can switch to other hole drill till lock back .The only tunable /repeatable one I have found that is push button lo pro. Comes with 2 plates so you can change loads or if you screw up .

 

[WxWatcher]

I'm using an adjustable gas block by Kies and got it from JoeBob's. Clamp on or set screw for $43 or $33, respectively. The adjustment is on the side and I can reach it without removing my Seekins MSCR V2 rail, but with another rail you may not be as fortunate. Don't have a lot of use with it yet, but so far it's worked well for me.

 

[Hollywood 6mm]

I'm using an adjustable gas block by Kies and got it from JoeBob's. Clamp on or set screw for $43 or $33, respectively. The adjustment is on the side and I can reach it without removing my Seekins MSCR V2 rail, but with another rail you may not be as fortunate. Don't have a lot of use with it yet, but so far it's worked well for me.

Sorry, what did you say? I was too busy watching your signature block...

 

[McLarenross]

Another vote for SLR. Expensive but worth it 100%.

 

[Djstorm100]

Syrac is good to go too.

 

[Keith E.]

Syrac get good reviews over on M4.

Keith

 

[Ballista One]

Without the can, I get consistent ejection between 3 and 4 o'clock, with brass being launched 25-25 feet. With the can installed, the ejection shifts to 1:00 to 1:30, and about 4 feet. Obviously the extra back pressure from the can is over-gassing the crap out of the gun.

Nothing is obvious...

All adjustable gas blocks are problematic. I get it, they are the latest craze for your AR-15 and everyone needs a unit on their rifle or carbine. If your weapon is completing the cycle of operation reliably, and by your account it is, your wasting time and money installing one. There's this belief that adjustable gas blocks have a linear effect on gas metering and a corresponding effect on bolt group speed but the simple fact is they don't. That is to say that each click of adjustment doesn't equal a corresponding unit of gas regulation. A crude little cup tip set screw can't effectively meter anything. Given a specific cartridge, they are either on or off. Once you have opened the adjustment screw to the point the rifle completes the cycle of operation, opening it further has ZERO effect on bolt group speed. The change in ejection pattern you are experiencing is a result of gas trapped in the suppressor equalizing through the barrel, not the gas system.

 

[Djstorm100]

Nothing is obvious...

All adjustable gas blocks are problematic. I get it, they are the latest craze for your AR-15 and everyone needs a unit on their rifle or carbine. If your weapon is completing the cycle of operation reliably, and by your account it is, your wasting time and money installing one. There's this belief that adjustable gas blocks have a linear effect on gas metering and a corresponding effect on bolt group speed but the simple fact is they don't. That is to say that each click of adjustment doesn't equal a corresponding unit of gas regulation. A crude little cup tip set screw can't effectively meter anything. Given a specific cartridge, they are either on or off. Once you have opened the adjustment screw to the point the rifle completes the cycle of operation, opening it further has ZERO effect on bolt group speed. The change in ejection pattern you are experiencing is a result of gas trapped in the suppressor equalizing through the barrel, not the gas system.

The Syrca does not use the allen screw it self to regulate the flow from what I can tell.

 

[Ballista One]

The Syrca does not use the allen screw it self to regulate the flow from what I can tell.

The clarify my previous statement regarding cup tip screws, neither the Syrac or SLR model uses a cup tip screw. They both use a machined screw. Of the versions I have, the latest generation Syrac has the highest adjustment screw machining quality. I've spent the last few months in my garage lab and at the range running 5 different adjustable gas blocks through a series of evaluations to see if one or more does what I don't think any of them can do.

 

[John_in_WYO]

I've spent the last few months in my garage lab and at the range running 5 different adjustable gas blocks through a series of evaluations to see if one or more does what I don't think any of them can do.

Would you share what you found?

Like many others here and their rifles, I'm considering an adjustable gas block for my rifle, Core 30 TAC LR.
It beats the hell out of my brass and ejects to 1 o'clock.

Thanks.

 

[Tangodown911]

SLR for the win. I have two. One on a 11.5 and the other on a 18". Both handle the issue just right.

 

[Hollywood 6mm]

Nothing is obvious...

All adjustable gas blocks are problematic. I get it, they are the latest craze for your AR-15 and everyone needs a unit on their rifle or carbine. If your weapon is completing the cycle of operation reliably, and by your account it is, your wasting time and money installing one. There's this belief that adjustable gas blocks have a linear effect on gas metering and a corresponding effect on bolt group speed but the simple fact is they don't. That is to say that each click of adjustment doesn't equal a corresponding unit of gas regulation. A crude little cup tip set screw can't effectively meter anything. Given a specific cartridge, they are either on or off. Once you have opened the adjustment screw to the point the rifle completes the cycle of operation, opening it further has ZERO effect on bolt group speed. The change in ejection pattern you are experiencing is a result of gas trapped in the suppressor equalizing through the barrel, not the gas system.

While I understand the "If it's running, don't screw with it" mentality (and I usually agree), I don't really care for the idea that my BCG is getting the snot beat out of it with the can attached. Since an adjustable gas block will make it possible for me to adjust this, it seems like a smart investment.

 

[rg1911]

And yet another vote for the SLR gas block. I liked the first one so much that I bought three more for my other ARs.

Richard