I'm working on another rifle build and need your guy's input. BLUF: Is a Supurlative Arms Adjustable Gas Block reliable for duty/shtf/TEOTWAWKI use?

A short little back story, I love 12.5in rifles for general purpose and I'm always looking for ways to cut weight on the front end of the rifle. I picked up a FAXON 16in Pencil barrel for $95 shipped off of the EE that I'm going to have cut down to 12.5in. This should be the lightest 12.5in midlength barrel I can get/make... for that price I just couldn't resist doing another project build just for fun. It has a 0.078 gas port which is right in between my MicroMOA 12.5in Midlength builds which have settings that work at 0.070 and 0.082. Theoretically, all things kept the same, it should work.

Below are the options that I could use some input from you guys. Any insight or experience regarding the topic would be greatly appreciated. Thanks!

- Option 1: Saving weight on the front end (Battle Arms Development Ti Gas Block) and increasing reliability by using a Gemtech or Bootleg BCG to make it run suppressed.
- Option 2: Utilize a Supurlative Arms Adjustable Gas Block. Allows me to fine tune the system especially when running suppressed, weighs slightly more (negligible really), obviously more complicated than a standard gas block and could theoretically break.

Rifle Specs:
- The rifle is intended to be a general purpose/SHTF rifle that will be ran suppressed 80% of the time.
- The rifle is a no compromise build and $$$ is not a limiting factor. Weight mitigation, performance, and reliability are worth the premium to me.
- 12.5in barrel (FAXON 16in pencil cut down, 0.078 gas port)
- Either SilencerCo Omega w/ Direct thread or Specwar 556k (Haven't decided yet)
- Geissele Super 42 buffer system w/ H-1 buffer
- Ammo: Brass cased 5.56 spec ammo (62 and 77gr) exclusively. Not looking to run any cheap steel cased ammo.

Couple threads running now about them.

I have two of the venting type.

The one on the GII (.308) it may work, I don't know for sure.  During the set up I turned the adjustment screw all the way out past where it would "click".  The rifle never stopped working.  So, while it may vent, by the instructions it should have stopped working (due to venting too much gas) somewhere between 4 turns out and all the way out.  It didn't.  The rifle functions 100%, again, not sure it's doing any venting.

The one on the 18" .223 doesn't seem to work.  It has a very narrow adjustment/working range of three clicks.  If I turn it out, or in, two clicks from the screws current setting, the rifle starts short stroking.  Might be the rifle, maybe it's borderline for having enough gas to work at all, since I never had a standard gas block on it, I can't say.  I'm not pulling free float tube and gas block off to drill the gas port out larger just to see if the gas block will then work as advertised.

I don't think I'll buy another one though.

Just my experience with two of them.  Some people say they work great.

This is what made me ask the question, but seems to be operator error?

Sample size 1.

I’ve used mine on .308 for about 1500rds, it works as advertised and helps with blowback suppressed

they seem more appropriate for piston systems than they do DI systems.

gas blocks erode, adjustable or not.  Just part of the game.  Typically you won't have erosion problems without *LOOOOTS* of ammo going through it.  and by that point, either the gas tube could fail or the barrel could just be ready for replacement.

I'll probably stick with SLR blocks just because they're simpler and don't have a 97-step "adjustment" process.

Really wish Syrac hadn't gone under.  I love the 3 blocks of theirs I have.

I've seen more hit or mess reports on the SLA than I have on the SLR. I don't know about SLA, but SLR appears to be user serviceable as well. Grab a parts kit and I'm not sure what could go wrong at that point.

No luck for a 18” rifle length gas system .308.  Stock gas block works great but I couldn’t get mine to function.  Even on full gas it wouldn’t strip a new round.  I just put on the factory one and I’m trying to see about a refund/exchange.  I see other .308s with no problems. Maybe it depends on the rifle.

Yes, this is true. In all likelihood you can probably use it for duty use or whatnot.

However, this illustrates the type of failure that could occur. You'll have a one shot rifle if it ever goes.

Why risk it when a low pro gas block exists that can shoot until the barrel goes?

(BTW, 1500 rounds is nothing and is no more valid than the guy whose broke his)

The 1500rds was more of a testament that is has withstood recoil and increased gas volume vs. a 5.56. Personally, I’m with you, for a duty/sd/serious use gun, permanent and non-adjustable removes variables of failure.

Ordinarily I'd say pin on an non adjustable gas block and go with H2 buffer.

But with a pencil 12.5 middy? You're in uncharted territory. I don't even think there is enough meat on those Faxons to make a new shoulder after cutting.

My thoughts as well. Personally, my hard use rifles all have pinned, non-adjustable gas blocks and FA carriers. Adjust buffer and spring if necessary. Not sure if that will work with your choice of barrel.

Simplicity is beneficial to reliability.

I logged in to say exactly this. Mid 12.5 leaves little dwell time and adjustable gas blocks only help reduce the amount of gas down.

No. For Utmost reliability, SHTF, fuck all, I say standard gas block. Get heavier buffer and spring to deal with increase pressure and firing rate with a suppressor. If youre worrying about your face getting dirty or breathing a bit of gas in SHTF, youre whats for dinner.

Or, get a switch block. There is no need for the massive amount of variation in adjustment when it comes to shitty situations. "Oh shit, I need more gas! Fuck! Wheres my allen wrench? Hold on, it is my pouch. Which one?!?"

You dont want to be thinking about this stuff during these situations. Thats why a switch block makes sense. Like Noveske, FAL, or the SCAR I believe as well. There is not infinity adjustments, its full, suppressed and off. Some throw adverse in there. The 15 clicks, infinite adjustmnet stuff is too much for SHTF/Duty weapon.

Theyre great for competition guns. But not when youre life is on the line. Or someone elses. As simplified as possible. That fancy shit will get you killed. Just my opinion.

No doubt.  Why the boutique parts for a SHTF build?

A lot of variables get introduced with adjustable blocks, not least of which is the user's knowledge in setup.  That's not to imply anyone is an idiot, but if you're going to absolutely count on one, all those variables need to be sorted out thoroughly.

That said, I have adjustables from SLR, Superlative, Odin, Seekins, maybe even others in the armory I've forgotten.  All have been setup and tested where I'm comfortable with them for range and competition use … but if the zombies are coming over the hill, I'd probably still grab a gun without moving parts in the gas system.  And really that's the purpose I see for adjustable blocks, to make guns more pleasant to shoot - not for making them more reliable.

Mostly because I can. I like to push things to the limit. This build was all about saving weight on the front end. The main reason for having an adjustable gas block was to: 1) Make it run more reliably with a suppressor. Having an action over running too fast because it's over gassed is more prone to malfunctioning. 2) Reduce gas to the face. Gas in your eyes is distracting and can make them water pretty good sometimes depending on the rifle/suppressor combination.

If it turns out that this rifle isn't reliable enough fro SHTF, that's ok. then it'll get down graded to a range toy. I have plenty of other rifles that have proven themselves.

Of all those gas blocks which one stands out as the best to you and why?

Buy a properly gassed 12.5" carbine barrel and be done with it.

You're just asking for issues otherwise.

Could you get it to run? Sure. But why give yourself the headache?

Not to mention the added variable of a questionable adjustable gas block.

If you're dead set on the 12.5" mid concept, I'd suggest contacting Clint at BRT and having a look at their gas block inserts.

http://www.blackrivertactical.com/concrete5/customtune-gas-port/

I have a couple and even though I haven’t had issues I’m switching them out for adjustable bcg’s

I really like the Black River Tactical gas block; might just be the ticket. Does anyone have any experience with this? I like how simple it is; how you can tune it, but the setting is semi-permanent. I am also interested in their gas tubes where I could get a titanium gas block and tune it down with a gas tube.

Other than a properly ported barrel from the beginning, this is the next best choice. I have one on a suppressed 11.5" BCM and it performs as advertised.

How did you choose your port size?

The Odin and Seekins both were set em and forget em.  Mounted under rails, and haven't been messed with since initial setup.  They've functioned well for that purpose, and haven't felt the need to adjust them since, as both have been consistent.

I have maybe 5 SLR blocks, and 2 Superlative.  Both of those have been tinkered with more, primarily because the design lends itself to easy/quick adjustments.  As far as function once adjusted, both have been what I need them to be.  The Superlative is more finicky to find that sweet spot across a variety of ammo, but no big deal.  I have a couple SLR blocks with maybe 3000 rounds through them, no issues have popped up.  My most used Superlative block has a similar round count, and just so happens to be on one of my favorite guns.

If I had to pick one and standardize across all my rifles, I'd probably go with SLR.  I like the way the clicks feel better, and it the "click to expected result" with it has been very consistent across a variety of guns.

I haven't torture tested any of them.  But can say that if you added up all the rounds I've put through a varitety of adjustable blocks, it's probably 10-12K, and I can't say there has been a single failure caused by the block.  Any failures have been during the adjustment period, and once adjusted all have performed well enough to forget they're even there.

I talked to people who had cut-down 6920s (0.0625") that didn't open up their ports, and consulted with Clint at BRT.

I set up mine to run 99% suppressed with 5.56 ammo. I wanted it to still lock back unsuppressed with Federal Fusion 62gr .223 as that is my HD/SD round currently.

I am also running the Vltor A5H4 buffer system.