Gemtech Suppressed Bolt Carrier: Reliable Offgassing and Function


Minimizing Gas Face for Left-Handed Shooters While Improving Suppressor Systems

I was recently given the opportunity to check out a new bolt carrier group from Gemtech, dubbed the 5.56 Suppressed Bolt Carrier. John Hwang, from Rainier Arms, loaned me one to try out as he wanted to get my feedback as a lefty shooter. Now I joke about "lefty problems" a lot as a minority southpaw, but shooting on the AR platform as a lefty with spent brass winging past your face, my schnozz is much closer to the ejection port than for our right-handed brethren. Gas Face. It’s a thing.

I’m a DI (direct impingement) guy, and none of my current builds are piston guns, or equipped with a switchblock or adjustable gas block on them. This posed an issue when I entered the suppressor game, as now my wonderfully-running rifles were overgassed with a suppressor mounted. Instead of building new uppers, breaking out pinned/welded muzzle devices to swap out gas blocks, messing with buffer weights or whatever workaround was out there, I thought that out-of-the-box, the Gemtech SBC might be a viable simplistic solution for overgassing.

The Gemtech SBC intrigued me right away, as the documentation on their website boasted some pretty cool claims such as reduced carrier speed in the suppressed setting, less felt recoil, unchanged carrier velocity while in the unsuppressed setting, less blowback in the operator’s face, and reduced wear and tear on the weapon system itself.

Gemtech also provided some bolt velocity testing results right in their product description so that prospective buyers could see bolt velocity suppressed and unsuppressed in both the 5.56 and 7.62 BCG platforms. Pretty transparent.

After I unpackaged the bolt carrier, I have to admit that I was a little surprised that the carrier itself was not complete – the user must provide their own bolt, cam pin, firing pin, and cotter pin. For my review, I stripped out the necessary components from one of my trusty Fathom Arms nitride BCGs that had already proven itself reliable in one of my previous builds.

The design is relatively straightforward. The inside-facing wall of the carrier has a two-position switch that can be turned using a flathead screwdriver or the rim of a shell casing. “S” for suppressed, and "U" for unsuppressed. For running unsuppressed, make sure the selector is on "U," and run the BCG as any other. For suppressed, the user must break down the rifle, withdraw the BCG, flip the switch to "S," and reassemble. This opens up a port within the carrier itself that ports the gas pressure out of the side of the carrier.

For my short evaluation period, the rifle I used was a San Tan Tactical matched receiver set build with a 16" Bravo Company middie barrel, Advanced Armament Corporation 51T flash hider, 556SD suppressor, and H buffer. Ammunition was standard off-the-shelf 55gr 5.56. Since this was a brand new build, I lubricated the necessary parts with Lucas Extreme Duty Gun Oil, and got to work.

Shooting the rifle unsuppressed with the Gemtech SBC was unremarkable, the San Tan Tactical build performed as all of my other San Tan Tactical rifles and pistols perform – which is very well. Shooting was controllable, and I really couldn’t discern whether or not there was that much of a difference in felt recoil from the carrier itself. There were no timing issues, and my build performed without a hitch.

I switched the selector switch to "S," and started with single shots up to straight mag dumps. Color me impressed. With the selector on "S," shots were controllable, recoil definitely was softer, and the notorious "Gas Face" was greatly reduced. I don’t want to over-exaggerate, this is not a be-all end-all solution. That being said, from strings of 10-15, 10-20 or so, the controlled porting of gas through the side of the carrier made left-handed suppressed shooting much more tolerable.

"…shots were controllable, recoil definitely was softer, and the notorious "Gas Face" was greatly reduced."

With the configuration I ran, I had no failure to extract, feed, or failures of any kind. The Gemtech SBC did not seem to affect bolt carrier timing at all, either suppressed or unsuppressed. I think this is a very viable option for those that run dedicated suppressor systems, or for left-handed shooters like me, who live with the fact that our faces are closer to the ejection port than our right-handed brethren.

I hope to be able to hang on to the BCG for a little while longer, I would like to check it out on my 300BLK pistol, as well as on a 14.5" build with differing buffer weights. As always, I’ll circle back around with updates as they come up.

Want to know more about Gemtech? Check them out at and Facebook.

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