I am finally going to add an adjustable gas block to my rifle. After a Gemtech BCG and PRI gas buster, my DD MK18 W/AAC M4-2000 still is unbearable to shoot past 5-10 rounds without goggles…
I need help determining the style of gas block. Superlative Arms offers a solid model with set screws and a clamp on model.
Take a look at the SLR adjustable gas block. It’s a durable design and if it ever has problems, SLR will take care of it promptly. Adjustment is easy and the clicks are positive. Mine has withstood the heat and fouling inherent to shooting with a suppressor.
I prefer the set screw design over the clamp-on. Set screw gas blocks usually have a smaller profile and I’ve never had one come loose. The set screws can be staked for insurance. The screws of the clamp-on style are prone to breakage. As the clamp closes, it changes the angle of the screw holes which bends the screw. Additionally, the screws are stretched as they are tightened. Coupled with the bending, the screws have to deal with more stresses and tend to fail more often.
When when a set screw gas block ins installed, tightening the set screws presses the top of the block against the barrel, helping to seal the gas block to the barrel. Set screws are compressed when tightened instead of being stretched, which keeps the screws from breaking.
I’m pretty happy with the set screw version of the SLR I bought.
That is very helpful… Thanks!
A clamp on may not fit under the RIS II rail either. It’s pretty tight, especially on the bottom. Have you considered a Black Creek gas port reducer or a new barrel? I shoot a Colt SOCOM cut to 10.3 and ported at .070” with an M4-2000 and a stock BCM Mod4 charging handle. No blow back issues. I simply don’t trust adjustable gas blocks. Too much failure potential at the most critical point of the operating system.
I can speak with confidence that, after what I have put the SLR adjustable gas block through, it’s going to take a lot of abuse before it fails.
This isn’t to take anything away from the Black River Tactical micro ports. The micro port is a simpler design and has no moving parts. I’m putting one through it’s paces now. It is more difficult to swap micro ports than it is to adjust the SLR. But once configuration and buffer is settled on, I think the BRT micro port is an elegant, reliable and cost effective solution for an over-gassed AR.
I chose clamp on for accuracy. It would be good to do a dimple + taper pin install on a hard use rifle. With the pin, you will have no worries.
i prefer Superlative Arms’ bleed-off design over SLR’s restriction method
for more info check you-tube for mike bell’s useful vids on SA gas blocks:
https://www.youtube.com/watch?v=0y02vdDzRUk
https://www.youtube.com/watch?v=UwHA9pvkgYA
i’ve found the clamp-ons are too big to fit inside some small-diameter rails (ie: BCM KMR).
I went with the SLR. I am concerned that the bleed off will become plugged with carbon and change the vent size. But I haven’t heard of any problems so I could be wrong.
I would still pick the SLR after using one for a little while now. I like the quality.
Make sure that if you have and existing dimple that it fits. And if you don’t have a dimple I suggest buying a decent jig.
Bingo. Two best options on the market between BRT MicroTune gas block and SLR set screw gas block.
They both sell a lot of gas blocks. This means large sample sizes. High reliability has been reported on both for some time now.
Note that for ANY adjustable gas block, they are not designed to be toggled between settings like a gearshift in a car. The adjustments are designed to be tuned upon shooting the rifle and then to essentially be left in that setting until such time arises that I knew tune needs to be established based on a change in configuration of the gun. The people who have gotten into trouble with adjustable gas block‘s are the ones who constantly screw with them and constantly change settings. This is not what those gas blocks are designed to do.
I can also confirm that needlessly toggling between the adjustable gas settings on, say, an FN FAL or a Sig 55X series rifle will also lead to early mechanical failure of those adjustment mechanisms.
So, to everyone who employs an AGB: STOP F$&@ING WITH IT.
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