Why You Need an Adjustable Gas Block for your AR

AShooting Journal ^ | 6/23/2015 | Brian Hormberg

[wrench]

Tune the rifle by adjusting the gas hole, not some mickeymouse add on.

[Lurker]

Interesting. Thanks.

[Durus]

The “gas hole” is not adjustable, hence the adjustable gas block. Which isn’t really a micky mouse add on as every AR has a gas block.

[Redcitizen]

just a bit of humor about mini-14s. Apologies in advance. :)

[wrench]

The barrel is dirt simple to change, and barrels can be ordered with any size hole desired, or no hole at all.

Adding another failure point to any weapon is never a good idea.

[wrench]

And any gunsmith worth a screw driver knows how to adjust any gas hole, up or down.

[Durus]

You can't adjust a gas system with a screwdriver unless you have an adjustable gas block. If you increase the size of the gas hole in the barrel you could then be restrained by the hole size and chamber of the gas block. To get beyond that limit you would need to increase the hole or chamber of the gas block. If you start getting too much gas then there is no way to go back unless you want to replace the barrel and/or gas block. Why anyone would make permanent alterations to their rifle for one type of ammo is beyond me, but go for it if you want.

I've never heard of an adjustable gas block failing and if it's good enough for competitors who tax their ARs to the limit then it's good enough for anyone. Further it's not like they were invented last week, they have been around for decades.

[Tijeras_Slim]

Or as we call it the “Wheel of Misfortune”.

[Windflier]

Thanks for the post. As a new AR owner, I’m trying to bone up on everything about my rifle. For now, I just need to get to the range and shoot the crap out of it.

[RC one]

I’m hoping it solves the problem of excessive back pressure associated with suppressors. The ability to reduce felt recoil in a .308 AR10 will be nice too.

[wrench]

A lighter bullet helps felt recoil, the 125 gr SST from hornaday is noticeably more comfortable to shoot than the 147 gr mil loads.

Gas guns and suppressors are not made for each other, if you cut the gas to the point you notice a difference, you will cut the reliability of the weapon. If it is just a paper puncher, dial the gas back to zero and open it up a little at a tile till it works again. The best solution is a bolt gun.

If you reload, you can custom load ammo that is not as gassey by using different powders. With commercial ammo, you are pretty much stuck.

[RC one]

I think the increased blowback caused by the suppressor is increasing the bolt carrier's rearward velocity and causing rounds to eject at 1 o'clock or worse and those rounds are hanging up inside the receiver where it jams the rifle up as the bolt travels forward. I need to slow the bolt's rearward velocity down and bleeding off gas at the gas block seems like it ought to do it. We'll see. It's on the way. If not, back to the drawing board. I'm not wanting to change the load as it shoots really really well in all of my guns.

[wrench]

The suppressor increases the gas pressure and volume, there is not a blowback effect in the bolt cycle.

Your suppressor effectively lengthens the barrel and causes more gas dell time on your pressure chamber in your bolt carrier.

Have you looked into the suppressor bolts now available? They have a suppressor/no suppressor adjustment and reportedly work well.

Most semi-auto guns run well on one type of ammo. They can be set up for whatever you want, but trying to get one to run on everything is a lesson in frustration. Set the gun up for suppressor only use is optimum .

[RC one]

The Gen II recon uses a proprietary bolt and carrier. I don’t know that I want to replace it or if I even could given that there’s no such thing as a mil spec AR10. If we were talking about a mil spec AR-15, I would consider that option. I’ll see if the AGB solves my problem which I am pretty confident is overgassing secondary to the suppressor. I like the idea of being able to just switch back and forth between settings for suppressed and unsuppressed. If it doesn’t work I’ll start messing with buffers. I think it just needs retuned for the suppressor.