Hardware Talk: Gemtech Direct-Thread Rear Caps

Looking to easily swap your suppressor between multiple firearms? Here we take a look at Gemtech’s direct-thread rear caps.

A lot of suppressor users are not going to swap their silencer across a whole rack of rifles. Not the first suppressor, anyway. It will spend its range time on one or two—maybe three rifles—ever.

If that’s the case, there’s no reason to invest in a QD mount system. Oh, they are cool, but they cost and add weight. A typical rear cap for a quick-attach system, and the muzzle brake it fits on to, can run up to 7 ounces. 

Especially on a rifle meant for hunting, 7 ounces can matter. The old hiking adage, “Look after the ounces, and the pounds will look after themselves,” comes to mind. So, Gemtech has now made available direct-thread rear caps for their new Abyss and Neutron suppressors.

They screw into the rear HUB threads on those suppressors. The HUB thread pattern is the new universal rear design, and if you have some other brand of suppressor that uses HUB, the Gemtech caps will also work.

The best part? If you have a 5.56 rifle, and the Gemtech Abyss 7.62, the 1/2-28 rear cap puts your .30 silencer onto your 5.56 rifle. Two rifles, two calibers, for one extra $52 part.

Will a .30 suppressor on a 5.56 rifle be as quiet as a dedicated 5.56 suppressor? You’d be surprised. Plus, the Abyss is going to shrug off pretty much anything your 5.56 rifle can give it.

At the price, you would be crazy not to be able to swap your silencer around. Oh, your barrels have to be threaded, but that’s common now, and they’d have to be threaded anyway.

The big deal is cost: Compared to the $52 of one cap to fit them all, each quick-attach sept requires a muzzle device. Depending on the brand, that can be $70 to $150 for each rifle. And we’ve been over the weight, which each rifle in turn is stuck with.

Now, you have to be careful. You must check alignment each time you install, because it’s prudent. And this mistake can be expensive.

Plus, there’s one more detail you have to keep in mind. Since the rear of the suppressor is the HUB thread, if you owned them you could inadvertently install the 5/8-28 rear cap on your HUB 5.56 suppressor. That would be bad. So don’t do that.

One way to avoid that is to use a paint pen, and discreetly mark your .30 and 5.56 suppressors and caps, front and rear. Say, blue for 5.56 and red for .30. The ease and versatility of the HUB design makes things simpler … but you have to be thinking.

And this isn’t just Gemtech: All suppressors using the HUB have this. So, pay attention.

But get the caps, they’re too good to pass up.

Editor’s Note: This article originally appeared in the January 2025 issue of Gun Digest the Magazine.

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