I'm currently ordering parts for my AR's and I want to know which route to go.

I've been told that adjustable gas blocks are better for use with suppressors (which I plan to do) but that they just add an extra potential failure point. Are adjustable gas blocks less reliable than non-adjustable gas blocks?

Also, I see that gas blocks range in prices, from $20 all the way the up to 150 or more for adjustable gas blocks. Does quality and reliability scale with price? Do you get a much better performing gas block the more you spend on it?

I was told by a very reliable and respected industry partner that AGB's are not necessary for 5.56.

7.62 however, they are game changers for suppressors

If you’re worried about reliability/complexity…

Just use a BRT gas tube.  Zero moving parts, zero extra parts, and nothing to fail.  It takes a bit more trial and error to get tuned because it’s not adjustable on the fly, but that’s what makes it as close to a milspec setup as possible.

Or achieve the same thing practically free by drilling your gas block for a set screw and drill the set screw for your desired gas port size.  Again, takes a bit longer to “tune” but there’s nothing to ever fail.

https://yhm.net/new-products/suppressor-gas-block/

Attached File

Just me, and I have adjustable gas blocks on some of mine.  If I was starting from scratch, standard gas block, low back pressure suppressor and adjust, if needed, with a buffer weight change. If going a short barrel, get the correct gas port for your needs.

Others will have different suggestions, because there are a lot of ways to tune an AR.

Question #1 - Have you ordered a barrel yet? If not, then seek out one with an appropriate gas port and avoid the issue all together. If you already have the barrel or you find the one you  picked is overly gassed for your needs, than a BRT gas tube is a great option. I've had AGBs with no problems, but unless you're trying to fine tune a competition gun or you shoot a wildly varying degree of ammo/set up, I've found the BRT tubes to be the easy solution. Tell them what your set up is, your ammo and suppressor usage and they send you a tube that's fits that criteria. Done

I appreciate all the responses, thank you so much. I have more choices now and I'll consider them when I buy my next barrel. The BRT choice seems the best to me.

I really like the Ridlespeed adjustable block.  Easy tooless adjustments.

For a fighting rifle in 5.56 I say fixed and preferably pinned.  Being a bit over gassed if the rifle is dirty etc may help.
  Suppressed DMR/Recce I like the adjustable. The Superlative Arms being the one I use in the gas bleed mode.
 As far as price I would always use a known quantity, but A2 fright sights worked for decades.  Long ago we just cut the sights down as a DIY low pro gas block.  
For adjustable I think the cheap ones do function properly, but I really like the SA.  Let’s be honest at this point your probability already in deep $$$ on your setup.  My DMR setup with suppressor is pushing $5k so why be cheap now.

AGB's have improved considerably since I bought one in 2012.  I bough a Syrac Ordinance (gen1.)  It had a hex keyed screw, and a button to push in order to adjust the screw.  A year or two later the button was replaced with a dimpled or keyed screw held in place with a detent and spring.  The release button was no longer needed.

It was pricey compared to a standard gas block due to the additional parts and assembly.

Although I play in the 300BLK world, I do run everything suppressed, supers and subs, and have really enjoyed the Superlative Arms (SA) gas blocks that I have.  Thousands of rounds, no problems.  No denying that adjustment is a bit of a PIA (depending on your hand guard and thus access with the hex key) I have had no problems with them clogging up or getting sticky.

Rifle Speed looks to be the bee knees though.  I don't have one, but I do expect to pony up the money one one of these days as I don't stick to just one ammo type and do wish for some on the range tuning from time to time.

Generally speaking though, I tune my gas block on a clean gun, with clean running ammo then open it up a bit to give room for crappy ammo and dirty situations.

All in all, after some tuning I find them well worthwhile.

I don't do builds without adjustable gas blocks anymore. They make everything so much easier and the rifle runs optimally. The only two adjustable gas blocks I would reccomend are the Superlative Arms (to set once and forget) and the Rifle Speed (on the fly adjustment for suppressed), depending on which way you want to go. I don't use the blow offsetting on the SA anymore because it can be a bit finicky to tune and you lose a few fps by venting vs. restricting.

There ARE lower limits on the quality of low pro gas blocks. I used a Sadlak (sp?) fixed gas block once that was under $20 to see how cheap I could go at one point and it was a freaking nightmare. The journal was too small at one end and had to be hammered on the last 1/8" and even using a small brass hammer, the steel was so soft it peened under a few strikes with a brass hammer. It had a gas tube roll pin hole too big for the inluded roll pin and it would not work. The finish was the worst bluing imaginable instead of parkerized or other quality finish.

For a fixed gas block of 0.750" I found BCM to be the best value. I don't like their 0.625" gas blocks because they use the same steel profile as the 0.750" gas block and just cut a smaller hole for the barrel. This makes the 0.625" gas block heavier, not lighter, like a propperly proportioned gas block. And if you are doing a 0.625" build, you probably care about weight. Also, BCM has a more gray finish than black but noone will see you gas block under the rail... but for some OCD people it's a thing. Otherwise, great kit at a great price.

I also prefer set screws with a circle ring of teeth to cut into the barrel and not require a dimple to be secure vs the pure tapered point style.

You only need a single dimple opposite the gas port if you have a barrel dimple. If your barrel has more than one dimple, be aware that set screw spacing for the set screws is a thing and you can end up with a set screw on the edge of a front dimple rim if you choose wrong. Not having a second dimple on a barrel is best IMO.

I don't reccomend a clamp style gas block because they often don't fit well under slim rails. There are some myths that a set screw gas block can harm accuracy vs a clamp style. I have found that to be utterly false, even on pencil barrels.

But no, you don't need a Badger Ordinance SPR gas block to build an upper. Just don't go uber cheap.

What are the differences in low profile gas blocks as money goes up? There are differences in  the hole that covers your gas port to make fit less critical, but a single dimple opposite the gas port makes that a non issue. The steel itself can be substandard only in ultra cheap blocks. The 0.750" hole can be under or oversized only in ultra cheap gas blocks. The finsh can be different. The set screws and spacing can be different. The gas tube roll pin hole can be nicely chamfered at the very end or not to make gas tube install easy or a pain and that hole can vary in size. The gas tube pin can be included or not and it's quality and size can vary quite a bit. I usually just use the one that comes with a particular gas tube. You also want to stay away from gas blocks that don't appear to be of the SPR profile shape as they can have fit issues under slim rails.

And if this is your first build... remember to install the gas tube BEFORE you install the gas block if the barrel is already installed or install the gas tube AFTER installing the gas block if the barrel is off the upper and you don't have an SPR gas block install jig. It's a pain to keep the block still and get that roll pin started. Finally, be sure you don't install your gas tube upside down and have to do your gas tube install a second time.