To go back a little bit, there are two (2) places that you can effect the amount of gas that is moved around the AR platform.

First would be an adjustable gas block which is attached to the barrel and the gas tube is slid into it. This, for most situations, is a more permanent attachment.

The second, and the one that we are looking at, is the gas key. This adjustable gas key made by Sun Devil Manufacturing is connected to the Bolt Carrier Group, BCG. The system is called ADIGS, Adjustable Drop In Gas System and it gives you the ability to quickly and easily change the amount of gas that is channeled to the BCG. One benefit that I see is that the BCG could be taken out and moved to a different platform or exchanged with a non-adjustable gas key if desired. Although after tuning and shooting it, I can’t understand why one would want to do that.

So why would one want to lessen the amount of gas that is sent to the BCG?

We’ll… this is important because the less gas that is sent to the BCG the less recoil will be felt as the BCG is not as forcibly moved reward. Of note and importantly, gas and recoil is needed. Sounds like doublespeak right… So as the Adjustable Gas Key is tuned, with a small screw that is placed inside the gas key, you are actually limiting the gas output. If you restrict the gas too much your BCG will not travel rearward far enough to eject the brass, or grab a fresh round or have enough force to seat the BCG. You are actually looking for the happy medium between too much gas, excess recoil, and too little gas, what we just reviewed. As you can see in the video and as I can attest to, when tuned it makes a drastic change to the way the rifle feels as you are firing.

The installation, which take about three minutes, if you dog it, could not be any easier. Everything that you need is included in the packaging. It includes:

1 – Adjustable Gas Key
2 – Socket Head Cap Screw 8-32 x 1/4″
1 – Bottle of Blue Loctite (# 242)
1 – Bottle of Red Loctite (# 262)
1 – Allen Key 9/64″ (Used for Install)
1 – Allen wrench 5/64″ Used to tune the Gas Key

Out of the package the ADIGS is adjusted to wide open, and will function the same way as the gas key that you just removed would. After restricting the gas, with the 5/64″ allen wrench, and taking a few test shots it is clear that this is where the ADIGS ease of use and functionality is seen. In less than ten rounds, I had my ADIGS dialed in. Now to rail on it… The felt recoil was considerably less. I was using 55gr FMJ, if you were to change ammo to say… 62gr you would just repeat the tuning process and you would receive the same results. In the last picture in the gallery (left), you can see the small set screw that limits the amount of gas that is applied to the BCG.

As you can see from the video (below) we went from 1.5 inches to less than 1/2 inches once tuned. I was not braced or anything for the “with” shots and I stood the same stance for both firings.

Check them out at and tell them Monkey from FourGuysGuns sent you.