Wilson Combat's adjustable gas block for the AR: something you need to be aware of...

This is a discussion on Wilson Combat's adjustable gas block for the AR: something you need to be aware of... within the General Firearm Discussion forums, part of the Related Topics category; An adjustable gas block allows one to adjust the gas bleed off that operates the bolt to match a specific load. Although not really needed, ...

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Thread: Wilson Combat's adjustable gas block for the AR: something you need to be aware of...

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    Wilson Combat's adjustable gas block for the AR: something you need to be aware of...

    An adjustable gas block allows one to adjust the gas bleed off that operates the bolt to match a specific load. Although not really needed, it does offer some advantages; even so, whether it's an advantage or not probably depends on applications. For a SD, HD gun the stock, fixed gas block might be wisest.

    For many other applications (other than SD), tuning the rifle has some advantages. One school of thought is that ARs are 'over-gassed' and simply doesn't need the forces generated to operate the bolt reliably. One advantage of tuning the gas bleed off is it reduces recoil by imparting less energy to the recoil buffer and spring. Another is that it bleeds off less pressure and hence increases velocity of the bullet a bit, although it won't be by much.

    All adjustable gas blocks have a problem - keeping the adjustment from changing. There are several approaches to this, Syrac uses a pushbutton to hold the adjustment screw in place so it can't move. However to adjust the gas port, you have to reach into and under the hand guard with something to depress the pushbutton and with the other hand do the same thing with an allen wrench and some how make the adjustment with both hands in the way of each other.

    Purportedly, Syrac is coming out with an 'indexed' version which 'clicks' into place and stays there. There's another company, JP I believe, that has an indexed version, but I know little about it or how it works.

    Well, I wanted a Wilson Combat adjustable gas block and it comes with the straight gas tube which is needed since the tube exits the gas block higher than normal due to the gas adjustment.

    Wilson's approach to locking the adjustment is to use a second set screw to 'jam' the adjustment screw in place. The funny thing about their system is that the 'jam' set screw has no bottom to it! It's basically a short, threaded tube with a hex socket head in it. Well, I found pretty quickly how problematic that could be. I called WC and that's the way they are; so there was nothing unique about the locking screw with my gas block. Here's a bit more about it and how I fixed the problem:

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    An adjustable gas block is mainly designed for guns that are run both unsuppressed and suppressed.

    Especially so for SBRs as they can be finicky because of reduced dwell times and higher pressure gas coming from the ports due to the port locations.

    With a suppressor on a SBR gun setup for un suppressed, the gun becomes overgassed and have failures to cycle properly (and vice versa)

    While, of course, they can be used to work to Tangle's goal of velocity, their raison 'd tete is to allow the AR to reliably function in wide variety of under/over gas situations due to using suppressors.
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    Quote Originally Posted by Chorizo View Post
    An adjustable gas block is mainly designed for guns that are run both unsuppressed and suppressed.

    Especially so for SBRs as they can be finicky because of reduced dwell times and higher pressure gas coming from the ports due to the port locations.

    With a suppressor on a SBR gun setup for un suppressed, the gun becomes overgassed and have failures to cycle properly (and vice versa)

    While, of course, they can be used to work to Tangle's goal of velocity, their raison 'd tete is to allow the AR to reliably function in wide variety of under/over gas situations due to using suppressors.
    I'd have to re-confirm this to be certain, but I'm pretty sure a lot of competition shooters use adjustable gas blocks to reduce recoil. I just can't imagine it reducing recoil that much, but then again, they're after any edge they can get.

    And, yes, that's another advantage I forgot to mention - adjusting gas for suppressed and/or SBRs.

    But, this isn't really about the why, it's just a heads up about the problem with the Wilson Combat adjustment method.

    The main reason I put it on this particular gun is because of all the reports of ARs not cycling correctly with subsonic ammo. That's true for this gun - it simply won't cycle 220 gr ammo.

    While the adjustable gas block won't solve that problem by itself, it is a component needed to resolve the problem the way I'm gonna do it.
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    I once put an adjustable gas block on a Mini 14 so I didn't have to leave my zip code to locate my spent brass.
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    Absolutely, you can tune the action to cycle at the slowest rate and softest recoil by using an adjustable gas block. It never takes long for the competitors to find something to give them an edge.

    But in an AR 5.56 platform, its primary purpose to was allow reliable cycling under various gas pressure regimes as suppressors were added and removed and ammo (sub-sonic to full power) was changed.

    As the SBRs meant to be suppressed are particularly sensitive as they are pushing the edge of the envelope for the design anyway and now you are screwing with ammo and pressure variables, you will see an adjustable block most often on those guns.
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    Quote Originally Posted by Chorizo View Post
    Absolutely, you can tune the action to cycle at the slowest rate and softest recoil by using an adjustable gas block. It never takes long for the competitors to find something to give them an edge.
    And once they do, you start seeing it find it's way into military applications, e.g. red dot sights, co-witnessing, shooting techniques.

    Quote Originally Posted by Chorizo View Post
    ...But in an AR 5.56 platform, its primary purpose to was allow reliable cycling under various gas pressure regimes as suppressors were added and removed and ammo (sub-sonic to full power) was changed.
    The problem is we are now putting a different caliber with different ballistic and pressure characteristics in that 5.56 platform, and from an internet search, cycling problems have arisen.

    Quote Originally Posted by Chorizo View Post
    ...As the SBRs meant to be suppressed are particularly sensitive as they are pushing the edge of the envelope for the design anyway and now you are screwing with ammo and pressure variables, you will see an adjustable block most often on those guns.
    Adjustable gas blocks (AGB) might help a finicky SBR, but they also help solve the big pressure difference between sub-sonic and super-sonic rounds in 300 BL. According to posts I've read, cycling issues are common with the AR in 300 BO and there seem to be only two options for dealing with the problems both incorporate an AGBs.

    One method is to adjust the buffer weight and/or the buffer spring to the subsonic load and get it locking the slide back on the last round, and then use the adjustable gas block to reduce the pressure for the supersonic loads so they don't over-gas and batter the gun.

    The reason the gas needs to be reduced for the supersonic rounds is because they have about 2.7 times more energy than the subsonic 220 gr round. Since the almost 3 fold increase in energy comes from powder which produces more pressure. The AGB allows the pressure that operates the bolt to be reduced to the proper amount.

    The other method and I think this is the direction I'm going, after I get some more info about it, is to open the barrel port a bit. The reason I like this method is it adjusts the 300 BO part instead of the 5.56 part. Meaning, it's more trouble to swap out buffers and springs if one wants to restore the gun to the 5.56 caliber. One of the attractions of the 300 BO to me is it just requires a barrel change.

    Weeeeeell, it turns out not to be quite that simple. One problem is Magpul mags have to be altered a bit to feed the 300 BO. The way I solved that problem is to use Lancer mags - I love those things. I got the 'see through' versions. And as mentioned, the other problem is cycle issues which could involve changing out springs.

    Soooo, if opening the barrel port and using an adjustable gas block will work, and I'm still researching that, then the buffer, etc. doesn't have to be changed and the gun can be swapped from one caliber to the other without having to change the buffer or buffer spring out.

    The sub-sonic is a blast to shoot in my unsuppressed 16" barrel, no pun intended, they're just fun! They are much quieter than a super-sonic round. The reason it is, is because the 220 gr sub-sonic has 2.7 times less energy than the 110 gr.

    The subsonic makes shooting at shorter ranges, kinda like shooting higher velocity rounds at longer ranges. It makes you think about ranges and bullet drop - pretty good training! And they're quiet. With my plugs in they just produce a puff - puts me in the mind of shooting a .22.
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