Adjustable Gas Block Reliability

[G31MT]

Have adjustable gas blocks gotten to the point of say "Duty" reliability? Picked up a used 11.5 BCM upper with an adjustable GB, and runs great suppressed and unsupressed, but wondering if reliability is a concern over a period of time and number of rounds. Would it be better to put a normal micro gas block on the upper or have the adjustables come this far? Adjustable in question is an SLR Sentry 7.

Thanks.

 

[Mike Erickson]

I've been running a Sentry on my suppressed BCM 11.5 for about 3000 rounds so far. It's only run at most 100 rounds without the can.

It does a good job of metering the gas, and the indented metering screw makes the maintenance easy. You're supposed to screw it all the way closed, then back it out to your normal setting after every range trip. I don't usually bother though, since I only run the gun canned.

I took a Dremel cutting wheel to the head of the screw and cut 3 slots that align with the indentations in the screw. This allows me to use a flat head screwdriver to adjust the screw if necessary, instead of using the original tiny allen head and possibly stripping that out. I don't think that would be a problem though, if you follow their directions. Otherwise, my technique and a little Kroil works pretty well.

 

[KevinB]

Frankly in DI guns that are properly gassed, the Adjustable Gas Block is unneeded, and unwanted.

Personally for a duty gun, I would dump it as it is just a liability waiting to happen, it just adds an unneeded failure point for zero value added.

 

[G31MT]

Thanks for the responses guys ultimately I am just looking for reliability so I think im going to ditch the Sentry.

 

[Dr. No]

Any time you suppress a rifle you are going to be dealing with an overgassed condition unless you reduce the gas port size which usually requires a barrel change. I would not recommend an adjustable for a non-suppressed rifle. The main issue with adjustable blocks is it is often difficult to tell if the adjustment screw is 'walking' on you, and you may not know until you start experiencing malfunctions. Interestingly, you may also experience that in many adjustable designs that the adjustment screw will seize in the block on its setting and if you do not break it loose frequently you will eventually be unable to adjust it. This may be a problem if you experience extreme weather shifts or go to a different elevation and you have the rifle tuned incorrectly. There are some designs such as the Micro MOA which have a plate that you can move side to side to choose your setting, however I didn't like the fact that the gas block leaked around the plate and would burn my hand in extended firing. Not an issue with occasional on duty use but if you have a high round count it gets annoying.

You also have to think of what roles your weapon will play. We run frangible ammo more than fmj due to our range restrictions. Those of us with personal rifles/cans did not want to run frang through our cans because most manufacturers will not warranty baffle strikes with that ammo. Due to that, I needed to be able to switch from suppressed gas to full gas. We also do a lot of sims work, but gas doesn't affect those kits at all since they are straight blowback. We have shot them with and without the can and have not experienced any loose sims heads in the can. We do check the bore and rattle the can after we use it as a precaution, however.

I personally have moved to using the Gemtech adjustable bolt carrier on my duty rifle. It requires no armorering to install, just a change of the bolt carrier. We have done a lot of testing in a couple of guns on both semi and full. My only issue is it is a 'one size fits all' which means it may not be perfect for your rifle, but it does the job very well and it's extremely easy to check the setting, even in the dark. It is inconvenient to change (have to take the bolt carrier out of the upper) so it's not something that's going to get bumped or accidentally changed. If for some reason the BC goes tits up, you can quickly swap your BCG or just the BC and have a rifle that is back up and running.

 

[Default.mp3]

FWIW, I tried to find a suitable adjustable gas block for my newest build, an 11.5" with a Surefire SOCOM. Couldn't find one that I trusted to fit under the WedgeLock, so I went with a gas block port insert instead to restrict the gas, along with the Vltor A5 RE, LMT enhanced BCG, and AXTS Freedom Bone. We'll see how well it works. I was happy with my MicroMOA on my 14.5" middy, but since it wouldn't fit the WedgeLock, I instead opted for these fixes instead (though I'm running the A5 and LMT e-BCG on the 14.5", too).

In theory, the A5 and LMT e-BCG should allow for a wider range of reliable use, including both suppressed and unsuppressed, while the tuned gas block should allow me to fine-tune as necessary. Hope it works, we'll see how it goes once I get it back in hand.

 

[KevinB]

You also have to think of what roles your weapon will play. We run frangible ammo more than fmj due to our range restrictions. Those of us with personal rifles/cans did not want to run frang through our cans because most manufacturers will not warranty baffle strikes with that ammo. Due to that, I needed to be able to switch from suppressed gas to full gas. We also do a lot of sims work, but gas doesn't affect those kits at all since they are straight blowback. We have shot them with and without the can and have not experienced any loose sims heads in the can. We do check the bore and rattle the can after we use it as a precaution, however.

Dr No. you may want to see if you can get jacketed frang -- Blackhills makes some good ones. Was designed for training usage with a can affixed.

 

[SoTex]

We went to full time suppressed use early last year on our issue Colt Commandos. We ended up with Superlative arms adjustable blocks along with a respring/rebuffer. In my rifle I know I have right around 5k live, couple hundred of the federal ballisticlean, and 2500 or so FX rounds. In that, I had no malfunctions attributable to the gas block.

 

[JohnsonCityTN]

I don't mind them for particular guns. I have a range toy AR pistol with an SLR adjustable block. That's simply because it's an 11.5 in Midlength barrel and requires some tuning to have it function 100%. I've not experienced any issues with the adjustment screw seizing or backing out in 600 rounds. (Relatively new build).

For duty use, I can't help but worry about it as another failure point. Ideally you run a gun with a barrel with a properly sized port.

My other carbines have either pinned blocks or simple yhm clamp ons tucked under the handguard that I know are rock solid.

 

[Dave_Thomas]

Early last year we had an issue with Syrac adjustables. 3 in a row shattered, one split right down the middle in the middle of a demo. We've since shifted away from them.

 

[WolfAlchemy]

I have been to 6 different fucking god damn forums, either I couldn't access due to needing a computer, having my Gmail not accepted as an email, which is bull shit considering it's one of the most widely used emails in the United States. Not only that I have spent the last three days looking for a god damn adjustable gas block and my set up requires me to have one where the adjustment screw is on the side, and I've found a bunch that will work yet they are completely drilled through and that shit doesn't make any sense to me unless the gas adjustment screw blocks off the top front hole. Never does. So can someone please explain why a gas block would be drilled all the way through it? I understand how the gas block system works, and the only reasonable thing I can think of is that they are reversible you just have to seal one end.

 

[Ryan St.Jean]

Unless you are running a can there isn’t any reason for it and I would switch to a standard gas block. Why borrow trouble?

 

[BooneGA]

I have been to 6 different fucking god damn forums, either I couldn't access due to needing a computer, having my Gmail not accepted as an email, which is bull shit considering it's one of the most widely used emails in the United States. Not only that I have spent the last three days looking for a god damn adjustable gas block and my set up requires me to have one where the adjustment screw is on the side, and I've found a bunch that will work yet they are completely drilled through and that shit doesn't make any sense to me unless the gas adjustment screw blocks off the top front hole. Never does. So can someone please explain why a gas block would be drilled all the way through it? I understand how the gas block system works, and the only reasonable thing I can think of is that they are reversible you just have to seal one end.

This isn't how you make a first post on a forum. Calm down.

You'll find that people are much more apt to help out.

Rick