The New Gemtech Abyss Quick Detach 5.56 Suppressor

With minimal gasses ejecting rearward, the Gemtech Abyss QD 5.56 suppressor works well and is much more enjoyable to shoot.

April 13, 2024 By Patrick Sweeney

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OK, the world is simply awash in 5.56 suppressors, so why this? Why now? Why the new Gemtech Abyss 5.56? (Because it just got a big brother in the Abyss 7.62, which is a slightly different kettle of fish.) Why? Because the world can always use a better 5.56 suppressor, that’s why. Gemtech has been around for a long time, and the advances under the name are many. In the process of developing the Abyss, Gemtech filed for and received five different patents, and we are the beneficiaries of those efforts. And in making the Abyss, they wanted to produce a hard-use suppressor that could stand up to whatever you or your rifle could. Let’s start with materials. The stainless steel tube is the sleeve for the baffle stack and the stack is composed of titanium baffles. The steel is 17-4PH, one of the rare stainless alloys that can actually be hardened through heat-treatment. (As an aside, it is also a magnetic stainless, another anomaly, but only of technical interest in its use in suppressors. Yes, I’m a mechanical engineering geek.) It is then given a black Cerakote finish. The baffles are made out of 6AL4V titanium, a heat-treatable titanium alloy, also known as a Grade 5 alloy. This means it is a great combination of being able to be fabricated, be welded, provide strength and be corrosion resistant. Just in case you were wondering, those are all good things for selecting materials for the inside of a suppressor. Basically, Gemtech selected the gold standards of suppressor alloys for use in the Abyss. (And the others in the new lineup; the Abyss 7.62 and the Neutron.)

gemtech-abyss-suppressor-02 — The gas flow out of the Abyss is obvious, and the lack of gas flow out of the ejection port is equally obvious.

On the back end, the Abyss has the new industry standard for mounts, the 1.375"-24 HUB mount. This is simply a large-aperture threaded end for the suppressor, into which you can install compatible adapters or mounts from any maker who is also using the .1375-24 HUB system. With this, you can use a direct-thread rear cap, or the Gemtech ETM QD mount. And, since it is the new industry standard, as other makers produce mounts, you’ll be able to plug them into the back of the Abyss. Why? Well, once you get into suppressors, you might want to own more than one. (Kind of like chips that way.) Wouldn’t it be nice if your various brands could all use the same QD mount?

So, the ETM, the Elite Taper Mount of Gemtech? That is the QD mount that Gemtech developed for use with the Abyss (and a Neutron-specific ETM as well) and it is both a mount and a muzzle brake. You get one with the Abyss, and you’ll have to go through the usual and proper method of installing a muzzle device, to make sure it is tight (use Rocksett) and square (use flat washers) and timed so the Abyss goes on properly. It is all in the manual. The ETM is also designed so that mounting the suppressor is easy. Line up the rear ETM cap notch with the ETM muzzle device notch. Slip the Abyss on until it stops, and then give it a twist counterclockwise until it stops. You’re done. Once you are done shooting, and the Abyss is cool, twist the Abyss clockwise to unlock. Once it stops, slide the Abyss forward off of the mount. Yes, it’s that easy.

gemtech-abyss-suppressor-03 — The GM-S1 front cap, and its removal adapter (top left). Place the adapter on the GM-S1, and use a regular ratchet wrench to unscrew it. An SBR with the Abyss is actually shorter than a regular carbine.

OK, inside the Abyss, Gemtech has spent a lot of effort designing the baffle stack, so it reduces back pressure. This, while still being quiet. The Abyss, while built for 5.56, and designed to take a lot of it, is also rated for the 5.7x28, as well as the new 6mm ARC. And to give you an idea of how tough they built the Abyss, it is rated for use on 5.56 and 6mm ARC firearms down to a seven-inch barrel, and the 5.7x28 down to three-inch barrels. (That’s absurdly short, by the way.) Now, on the front cap, the GM-S1, Gemtech also performed some trickery. The front cap is designed to minimize muzzle flash, and also to continue the forward flow of gases, adding to the design to reduce back pressure. The GM-S1 is removable, so you can do a better job of cleaning, should you wish to. (Me, I clean my 5.56 suppressors by heating them up enough to burn out any residues, and I don’t ever use them on rimfires.) The Abyss comes with the ETM, the suppressor assembled with the rear cap for use on the ETM, the tool to remove the GM-S1 front cap, an assembly wrench, and an owner’s manual. The suppressor is in a nylon pouch, and the whole kit is in a classy storage box, so it will have a safe home in your safe, and not be rattling around with the other gear in there. All you’ll have to provide is Rocksett, shims, an alignment rod, and a ratchet wrench if/when you go to remove the GM-S1 front cap.

My introduction to the Abyss was at a range in Florida, courtesy of Gemtech and Smith & Wesson, where I got to thrash the Abyss while it was mounted on the equally new Gemtech GVAC upper. This is a complete upper, also from Gemtech, that is designed itself to reduce back pressure. No, no magic, just good design and engineering, and the two together proved to be a fun combo to shoot. Now, there are times when you really should be jealous of gun writers, such as this time. We had loaner rifles with suppressors, a range to ourselves, and all the ammo we could put through the rifles. So, I proceeded to see how hot I could get the Abyss, and to see if there was any back pressure to pay attention to. The short answers are; very hot, and no. When you have finished a shooting session, then you put the rifle and its suppressor on a bench, and the wood gets scorched by the suppressor, you have heated things up. And the back pressure? Nope.

gemtech-abyss-suppressor-04 — To mount, line up the Gemtech Abyss mounting groove with the ETM mounting groove, and slide the Abyss fully on. Then give the Abyss a twist counter- clockwise, until it stops. You have mounted your Abyss and are ready to go.

Now, as a long-time gun writer, I’m always just a bit suspicious. So, I asked for an Abyss I could test back home, because, well, because. I’m a gun writer, which means I’m a professional cynic. The Abyss arrived in due time, and I spent a bunch of range sessions working it hard. It had arrived with a GVAC upper, so I first tried it on that one. I tried the full gamut of bullet weights, from varmint loads (but I didn’t go too low in weight, the GVAC has a twist of 1:8 and I didn’t want a varmint grenade grenading inside the Abyss) up to some Black Hills Mk 262 Mod-1C, and they all worked just fine and none of them produced any back pressure that my face could detect. I installed the ETM that came with it, and tried the Abyss on a non-GVAC carbine upper, for the same results; no gas in the face. However, I’m not the most sensitive when it comes to gas in the face, so I figured I’d make life harder for the Abyss. I wrenched the ETM off of the carbine, and wrenched it onto a short-barreled rifle (SBR) with an 11.5-inch barrel.

gemtech-abyss-suppressor-05 — The empty is on its way, and you can see (or rather, you can’t) the lack of ejection port gases that the Abyss provides, at the Florida range. (Mark Fingar photo)

I figured if I couldn’t get back pressure and gas in the face from this combo, then they were onto something. Well, Gemtech is on to something, because it was just as pleasant to shoot as it would be without a suppressor. Well, more fun, actually, as the muzzle blast from an 11.5-inch barrel is problematic just by itself, and using a suppressor to tame that makes it more pleasant. A few loads provided some small puffs now and then, but on other suppressors the SBR is a definite “gas in the face” when suppressed upper. One of these days I’m going to do a test to see what powder/bullet combos produce the most gas-in-the-face awfulness, and then test a slew of suppressors with that load. But that will be later.

The cool thing about a SBR-with-Abyss setup is that it is more than an inch shorter than a vanilla-plain carbine. Of course, it entails $400 worth of tax stamps, but hey, excessive fun comes with a cost, be it firearms or vehicles. The last test, which really wasn’t a fair one, was to park the Abyss onto an SBR with a seven-inch barrel. Back pressure? Yes, detectible, but not nearly as obnoxious as that one and all of them in general, usually are. No, scratch that, 5.56 barrels that short are extremely obnoxious, and the two things that makes them worse are putting a muzzle brake or suppressor on them. The Abyss strives mightily, and it makes the bark not quite obnoxious, but the gas system is so short nothing can eliminate back pressure. But the Abyss does a lot more than most, here.

gemtech-abyss-suppressor-06 — The ETM, the Elite Taper Mount, is the Gemtech QD muzzle device for mounting the Abyss. It is a muzzle brake, and it is also a very quick QD mount design. The GM-S1 front cap is removable for cleaning, and it works to both kill muzzle flash and to continue forward-flow of gases.

I don’t have a 6mm ARC yet to test it on, and the only 5.7x28 firearms I have are not threaded for suppressors. So, it was just 5.56 in this test. And quiet? The Abyss, on the GVAC upper drops the muzzle blast decibel level down below the “hearing safe” level of 140 dB, from bare muzzle 167 dB to 131 dB suppressed. I did have to take a shortcut on the testing. The GVAC comes with the ETM already mounted, and as a muzzle brake it is going to give a higher dB reading than the same barrel with an A1/A2 flash hider. Therefore, I used an otherwise identical setup, with a flash hider, of the base reading, and then measured the Abyss on the GVAC. One thing to consider when looking at decibel readings and comparing to your own situation is the environment. When I’m shooting a suppressed rifle out at the National Guard base, with nothing in my own zip code to reflect the noise, they are quiet. At my home club, where everything is close-by, the supersonic crack gets reflected off of every post, tree, bench and wall.

gemtech-abyss-suppressor-07 — The Abyss is a good-looking, hard-use 5.56 suppressor, and it comes with everything you need to mount it onto your rifle, carbine, SBR or pistol. (Mark Fingar photo)

There, they all seem louder. Keep that in mind when you are comparing “what it sounded like” from testing in different locations. All this for a list price of $849, and the world is your oyster. Oh, one detail, small though it might be. The listed weight is for the bare Abyss. Once you install the QD rear cap, and mount the ETM on your barrel, that will add another 6.9 ounces. This is unavoidable, and every suppressor maker has the same extra weight to get you a QD system. If you really want the lowest weight, the direct-thread rear cap will shave some four ounces off the full-up weight of 21.4 ounces with the QD rear cap and ETM. As I mentioned in the beginning, the world is simply awash in 5.56 suppressors, but while the choices may seem vast, the good ones are fewer. And the Gemtech Abyss is one of the good ones.