Adjustable gas block for a 16" carbine length rifle

[trvsAR]

Was curious of your guy's take on running an adjustable gas block on a carbine length rifle to simply cut off alittle gas to a rifle that is considered by most to be slightly over gassed?

Would you guys call this unnecessary fiddling with something that isnt broken? (honestly the response im most expecting lol)

A half decent idea considering mid length guns are much more popular these days?

Or something in between?

Thanks

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[kirkland]

If the gas port is sized right then it shouldn't be a problem.

[MistWolf]

I would do it simply for the experience. I learned a lot while experimenting with tuning my AR.

[1168]

Google “M4c sentry 7” or take a look at Black River Tactical’s offerings. I just ordered one of their EZTune gas tubes so I wouldn’t have to add moving parts to a gun I want to choke down a bit.

[markm]

I would definitely do it... assuming you don't have a fixed front sight base. Adjustable gas blocks work really well. You'll usually find only one setting that gets the gun running nice before the next lower setting starts to impact function. But that one setting is worth it.

[RobertTheTexan]

I’ll be that guy. I started out using SLR Sentry 7 and Wilson Combat adjustable GB on my SBR’s and precision AR’s. They work great until they don’t.

Since then my opinion on “go-to” rifles or HD/SD rifles is that an adjustable gas block introduces another point of failure that doesn’t exist with a low pro GB for example. If I had a fun, built only for fun - a range toy so to speak, then that might be different. I would agree that there is something to be learned from adjusting a gas block and seeing the impact the volume of gas has on type of bullet, .223 vs. higher pressure 5.56 for example. Or the impact it has on what happens on empty mag lock back, or when the bolt fails to extract. Definitely a learning opportunity and kinda neat to get your AR shooting as soft as possible. However I no longer view that as practical.

Ultimately, I have learned using a combination of things like barrel choice and an A5 buffer system can improve recoil impulse. Someone also taught me running a bead of high temp RTV along the “horseshoe” of the charging handle is a very inexpensive but efficient way to direct gas away from your face, when shooting suppressed, if that’s one of your goals.

I’ve shot one of BRT’s reduced port gas blocks. Shot it on a DD 11.5 (gassy SBR) and I won’t lie, that thing shot so flipping smooth it was like shooting a different rifle altogether.

So for me, it’s not worth it. There are possible some exceptions, but all my AR’s now use standard low-pro GB’s.


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[Nocalsocal]

Okay, I’ll bite .
What kind of failure did you experience? I know some adjustable gas blocks aren’t rated for full auto. Should I be worried if I strictly shoot in semi?



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[trvsAR]

Thanks for all the replies guys

It seems i should have specified some stuff

The rifle in question hasnt been malfunctioning and its not a go-to rifle in any way

I was thinking of installing a long rail on it anyways to try it out and see how i liked shooting a rifle set up that way

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[Clint]

Just to clarify a few concepts that are often conflated...


Proper gas drive and Optimal gas system configuration are two separate, but related things.


For example, a 16" CAR isn't necessarily overgassed; that depends on the gas port size.

But even if the gas port is correct, it will never be an Optimal configuration because the gas system is too short relative to the barrel length.

The only ways to make a 16" CAR barrel totally correct are to extend the gas system or shorten the barrel length.




Was curious of your guy's take on running an adjustable gas block on a carbine length rifle to simply cut off alittle gas to a rifle that is considered by most to be slightly over gassed?




The rifle in question hasnt been malfunctioning and its not a go-to rifle in any way

I was thinking of installing a long rail on it anyways to try it out and see how i liked shooting a rifle set up that way

[markm]

I’ll be that guy. I started out using SLR Sentry 7 and Wilson Combat adjustable GB on my SBR’s and precision AR’s. They work great until they don’t.


You've had Adjustables fail???

[Pappabear]

I used to think the adjustable had a toggle switch that was an easy failure point. But mine had detents adjustable with hex and felt much more secure than I previously thought. As has been stated, for HD ill stick with my perfectly gassed Colt 6945 or my LMT ....

PB

[Nocalsocal]

I always read about adjustable gas blocks being a potential point of failure. Assuming that the adjustable gas block is well made and from a respected manufacturer. What is the failure rate?
I'm using a Superlative Arms Adjustable with detents and it seems perfectly fine for my use. Semi, non suppressor and red loctited on a dimpled barrel. All under a MI handguard.
I used to think the adjustable had a toggle switch that was an easy failure point. But mine had detents adjustable with hex and felt much more secure than I previously thought. As has been stated, for HD ill stick with my perfectly gassed Colt 6945 or my LMT ....

PB

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[markm]

What is the failure rate?

I'm eager to hear RobertTheTexan's failures. I never even had mine get stuck on a setting.

[Nocalsocal]

Me neither
I'm eager to hear RobertTheTexan's failures. I never even had mine get stuck on a setting.

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[MistWolf]

I started with a 1st generation SLR that CoryCop25 pointed me to. For the next couple of years, I put a lot of rounds through it, getting it plenty hot. It stood up to everything I threw at it. Until I broke the adjustment screw. I broke it by coming at it with the Allen key at too much of an angle. When I contacted SLR for replacement parts, they told me to send it in and they'll send me a whole new gas block. Turns out in the time since I bought the SLR gas block, they'd made some improvements.

They sent me a new gas block with a more robust adjustment screw. However, it seems they got a bad batch of leaf springs that were not tempered correctly. The gas block wouldn't hold its adjustment. I contacted SLR again and they worked with me until the problem was solved. I think that was about a year and a half ago and although I run the SLR gas block hard, there have been no further failures. Adjustments remains easy to use, is positive and does not drift.

I like it because I can tune the upper for optimal function suppressed. This is an important feature because I run the upper 100% suppressed. If, for some reason I need to shoot the upper unsuppressed, all that needs to be done is the gas block be opened a click or two.

The other product I've tried is the BRT Micro Tune Port. I gave BRT the information about the upper (5.56 ammo, 11.5" carbine gas barrel, A5 buffer) and let them recommend the gas port diameter (.063"). Installation required removing the FSB and a little drilling & tapping, but that's the kind of thing I do as part of my profession. The setup has been absolutely bulletproof. One downside is, for my use, the gas port is a little on the large side. The upper will run with or without a suppressor. The other is that making adjustments (changing micro ports) is not simple.

However, both options are much better than living with an over-gassed upper or vainly trying to fix the problem with heavier buffers.

Note: ARs fitted with CAR buffers will feel over-gassed (have sharp recoil) even when the gas is set right.

[markm]

They work great until they don’t.

Third request, Dr. Ford.

[Clint]

We'll swap port sizes until you get the desired function.



The other product I've tried is the BRT Micro Tune Port. I gave BRT the information about the upper (5.56 ammo, 11.5" carbine gas barrel, A5 buffer) and let them recommend the gas port diameter (.063"). Installation required removing the FSB and a little drilling & tapping, but that's the kind of thing I do as part of my profession. The setup has been absolutely bulletproof. One downside is, for my use, the gas port is a little on the large side. The upper will run with or without a suppressor. The other is that making adjustments (changing micro ports) is not simple.

[opngrnd]

I've had a current-as-of-last-year SLR AGB stopped working and fail to accept adjustment. I had it replaced, set it back to the setting that was my go to for the upper, and it's been good(the AGB). But I'd use a lo-pro gas block with a BRT insert now, having seen 3 of the kits working. One of the kits went into a S&W upper to tame it, and the others went on buddies blem Optimum barrels(slightly oversized gas port was the blem). All three function very well without concerns of parts failing.

I'll be doing the BRT gas block w/insert from now on. It's cheaper, if that's a concern, and can't really fail. If I wasn't already set up I'd probably try the BRT gas tube.

[RobertTheTexan]

I'm eager to hear RobertTheTexan's failures. I never even had mine get stuck on a setting.

Me neither



Sorry about that guys. Didn’t notice someone had quoted my post.

Failure rate? My sample size is small. I’ve had 3 SLR SENTRY 7’s. One failed. I’ve had one Wilson Combat GB, this was before they started selling or partnering with SLR. It failed also. On the S7 there was no positive click on the adjustment screw. Furthermore I could not get enough gas flow to get my bolt to lock back on empty mag, additionally I could turn the adjustment screw with my finger. I contacted Todd at SLR and he had a brand new gas block with a return label in the mail the next morning before I even had the bad one pulled off. That wasn’t the first time I had interacted with Todd or Chase and their customer service in my experience, is outstanding. I can’t say enough about how they have taken great care of me in past 3-4 years. The new one functioned as advertised and I was able to tune my 308 to operate as it’s supposed to. On the Wilson Combat, the mechanism inside the gas block that closes and opens the port in the GB (I’m assuming) failed to adjust the gas flow to the closed position. I could turn set screw and it would not close. The good part of this was that it was stuck full open so my rifles would function as with a non-adjustable GB. Aside from a design that left a little to be desired (the Wilson Combat) they both did what hey were supposed to do until they stopped doing what they were supposed to do. I’ve had interactions with Dave Wilson (not sure if related to Bill or what, but a nice guy.)and Randall Robinson at Wilson Combat and they are just stand up guys imo.

The S7 clicked one day, the next it didn’t. Can’t explain it, but that’s how it happened. I never got the Wilson closed. It’s a tricky one though due to design, but I know how to adjust it.

So those are my experiences. I can’t say that it was these two experiences alone that changed my mind about using them on my weapons, because I continued to use an S7 on both my 308 and an 11.5” DD SBR and they functioned flawlessly. But at some point while discussing this with a buddy of mine, I came to the conclusion that an adjustable gb was a part that I did not have to have. Sure I enjoyed the tuning benefits, but it definitely fell into a nice to have which I measured against the must have requirement of reliability.



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[HMM]

I've got SLR adjustable gas blocks on every rifle, no issues at all. And their customer service is top notch, I ordered the wrong rail for my 308 upper and they exchanged it no questions asked. All my rifles have their rails too.

[RobertTheTexan]

Third request, Dr. Ford.

I must be tired because I was getting some stuff unpacked when it dawned on me what your “Dr. Ford” reply meant ya wise guy.

Yeah I am that tired. 🤤[emoji42]


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