AR adjustable gas blocks

[Boboclown]

Which one is a good option? A friend is wanting one for his suppressed rifle.

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[Mr Smith]

Can't say I'm a fan of them. The last one I had I couldn't adjust without taking the muzzle device and handguard off the gun, so it ended up seizing up. Even the screws to tighten/remove it were seized up and I ended up having to cut it off the barrel with a small cutting wheel on a dremel. It was a stainless steel gas block as well on a stainless steel barrel.

So that's not to sway you or your friend..more of advising to look for one that can be adjusted without disassembling the gun, and make sure to lube and work the adjustments regularly to prevent them from seizing up on you.

 

[titsonritz]

Can't say I'm a fan of them.

Nor am I. IMO, they add unnecessary complexity to issue that can be solved with a proper size gas port. I would seek out one of those barrels, such as a SIONICS with a reduced gas port. If the barrel has already been purchased Black River Tactical has verious options to correct it including custom tune port sizes and gas tubes.

 

[V4Cascade]

Can't say I'm a fan of them. The last one I had I couldn't adjust without taking the muzzle device and handguard off the gun, so it ended up seizing up. Even the screws to tighten/remove it were seized up and I ended up having to cut it off the barrel with a small cutting wheel on a dremel. It was a stainless steel gas block as well on a stainless steel barrel.

So that's not to sway you or your friend..more of advising to look for one that can be adjusted without disassembling the gun, and make sure to lube and work the adjustments regularly to prevent them from seizing up on you.

I have an adjustable gas block with under 1k rounds. Swapped out to a shorter barrel and noticed the adjustment was hard to move due to the carbon build up but it was still adjustable nonetheless. I've really considered just going back to a standard GB and avoiding further potential issues.

 

[Cerberus Group]

All will eventually fail. If they are set up right, you won't need one.

Tune with springs and buffer weight.

 

[Boboclown]

He was having issues because he was going from subs to supersonic ammo and used it on 5.56 as well. Though part of it could have been the factory remanufactured ammo, which I told him was possible.

 

[msgriff]

I'm going to partially disagree with most of the previous posts. I won't go into all the details as not to bore anyone, but there are about 8 different methods to tune a gas system, including an adjustable gas block. Not all AGB's are built equally, and I've had good experiences with a couple of different Mfg's on large frames. For the application of rapidly switching between suppressed and un-suppressed, the best option is a switchable or selectable gas block or bolt carrier. These provide 2 to 4 easy to operate adjustments. This would also apply to correct cycling problems due to switching from subs to supers. Some examples are:
1. Strike Industries Collar Adjustable Gas block
2. Seekins Precision Select Adjustable
3. Noveske SwitchBlock
4. Bootleg 4 Pos. Adjustable Bolt Carrier
5. Gemtech 2 Pos. Suppressed Bolt Carrier

Just my opinion.

 

[Cerberus Group]

Check out Chads videos from School Of The American Rifle.

Also, top makers don't use adjustable gas blocks for suppressed etc. But if you think you have to...they do require maintenance.

 

[msgriff]

One side note that may be of interest, there is a increase of people wanting selectable gas blocks with a "gas off" position to prevent the rifle from cycling.

 

[MfnLeadFarmer]

Welcome to Superlative Arms - PERFORMANCE DRIVEN DESIGNS FOR THE AR15/10 PLATFORM

This is the only design I think is worthy of serious use.

 

[osprey]

I have a custom light weight ar10 build in 260 rem that is severely overgassed. After some research I have decided on the superlative arms unit linked above. I have had it installed for a year but haven't run it through it's paces yet. This is on a hunting rig and I would never put one on a fighting rig. I will report back after some testing.

 

[308]

My experience with an AGB is that I forgot I tuned and zeroed my AR suppressed then later removed the suppressor to run on the .22. Next time I shot the AR it would not cycle . I'm sure this is not a unique experience.

 

[kbf64]

Agree with above, I think it's the wrong place to "fix" the issue...

 

[Boboclown]

I mean, its not MY gun, and he was deadset on an adjustable gas block so... I'd just prefer he get a decent one at least.

 

[daved20319]

Welcome to Superlative Arms - PERFORMANCE DRIVEN DESIGNS FOR THE AR15/10 PLATFORM

This is the only design I think is worthy of serious use.

This is one that I'm looking at hard, but I'm not quite sure I get the theory of operation. What is the "excess" gas that's being bled off? It sounds like they're saying it has two gas paths, one path to the gas key, the other out the front, and that it uses the same amount of gas that a fixed gas block would use, but instead of the "excess" staying in the barrel, driving the bullet, it's being vented to atmosphere. If that's correct, what's the advantage? I can maybe see it with a suppressor, but I don't run one. Is it still worthwhile with a pretty ordinary 16" carbine? Thanks.

Dave

 

[msgriff]

The lever looking thing on the right is the detent ball and spring housing. The hole at the lower left of the adjustment screw is the exhaust port, and that hole intersects the threaded adjustment screw hole along its length. The threaded adjustment screw hole intersects the gas passage that connects the barrels gas port to the gas tube. The exhaust port does not directly intersect the gas passage.
The first 4.5 revolutions from closed of the adjustment screw is restrictive mode, increasing the area of the gas passage in which the gas can pass, like most AGBs. 4.5 revolutions is full open, no restriction or bypass. The next 4.5 revolutions CCW (9 revolutions in total) is bypass mode, increasing the area along the threaded adjustment screw hole in which the gas can be proportionately exhausted forward. Gas will still flow through the gas tube in bypass , until it is easier to just go out the exhaust port than it would be to cycle the BCG.
Advantages of the bypass mode is based upon a couple of the gas laws of physics. One way to explain it is a "Y" splitter for two hoses on a outdoor hose bibb, each hose with a adjustment lever. Restrictive mode is simple, one hose off and start opening the adjustment lever on the other. Bypass is one hose full open, then start to open the second hose adjustment lever. The pressure/volume of the first hose drops proportionately. It is not linear when you introduce an opposing force upon the first hose, like your thumb on the end. Your thumb is the BCG.
Other advantages are reduced carbon fouling in bypass and self- cleaning of the adjustment screw when you cycle it. More info or personal experience if wanted.

TL/DR: Magnets

 

[titsonritz]

https://www.riflespeed.com/RIFLESPEED-Gas-Controls-750_p_12.html

 

[Ops]

love my adjustables, recommend them on all guns. work great and can adjust it to be reliable

 

[V4Cascade]

https://www.riflespeed.com/RIFLESPEED-Gas-Controls-750_p_12.html

Twice as expensive and twice as heavy with that shroud. No thanks. For the average shooter who's not shooting suppressed, this is a set it and forget it type thing. You're not going to be adjusting your gas every time you're going shooting and if you are you have other issues.

 

[P7M13]

I have an Odin and a JP.
The Odin is on an Aero M5E1 7mm-08, and has been useless and set wide open since two weeks of trying to adjust the sweet spot a few years ago. I now tune this with buffer weight.
JP on a 308 Aero M5. Adjustability is excellent. I took the adjustment tool they provided, cut off the 90° part & mounted it onto a Nut driver handle. Easy peasy adjustment .
Both AR10s have full mass BCGs.