First off, I sincerely apologize for my clickbait title – I am mostly poking fun at a site that loves to use out-of-this-world headlines. Literally. But in all honesty, the GSL Phoenix (formerly the Gemtech MK-9K) could possibly be the best submachine gun silencer ever made. Keep in mind however, like the rest of life, there is no free lunch. But before we get into the review, welcome back to the 110th installment of TFB’s Silencer Saturday brought to you by my friends at Yankee Hill Machine, manufacturers of the new Resonator K rifle suppressor. Fresh off of the whirlwind of SHOT Show 2020 I have stacked up a few months of reviews, starting with the YHM Resonator K, the Dead Air Nomad L, and three from GSL Technology. We’ll kick it off today with the GSL Phoenix – a grail suppressor for me ever since the MK-9K went underground.

SILENCER SATURDAY #110: GSL Phoenix – Best Subgun Can On Earth?

Introduction:

When it comes to suppressing pistol caliber carbines and especially submachine guns, internal volume reigns supreme. There have been huge advancements in pistol caliber silencer designs in the last decade – shorter, smaller diameter suppressors have become very efficient in decibel reduction. However, all things being equal, more internal volume will lead to better suppression. Additional internal volume is doubly important when dealing with fully automatic rates of fire.

So back to my original statement – The GSL Phoenix is the best subgun silencer on earth. Between the internal volume (large diameter, long length) and the baffle construction, yes, I believe The Phoenix and the MK-9K respectively are the best commercial submachine gun suppressors that are/were available. However the trade off is a longer, heavier suppressor as compared to more compact models that may not focus on ultimate noise reduction.

GSL Technology – Overview and History:

For decades, GSL Technology manufactured many of Gemtech’s most well known silencer models. For those that don’t know, Gemtech really didn’t have any production-level manufacturing equipment – commercial products were made mainly by GSL. That’s not to take anything away from the people at Gemtech – I don’t assume to know all the ins and outs of their old corporate structure and partnership with GSL Technology. TFB publish a series of articles in 2018, some of which came after our own Nick C. personally visited the GSL facilities in Jackson, Michigan.

GSL Technology – The Company

TFB GSL Technology Links:

• GSL Technology Pill Box Suppressor Coming Soon
• Integrally Suppressed Sten Suppressor Coming Soon From GSL Technology
• GSL Tech – Boss Emergency Suppressor

Background – The GEMTECH MK-9K

I reached out to some friends who used to be at Gemtech for information on the now discontinued MK-9K. Since the GSL Phoenix is basically a modernized MK-9K I thought it was important to include some background information. Of course, a few years a ago Smith & Wesson bought Gemtech and so far they show no signs of bringing back the subgun silencer line. Thanks to Derek, Alexander and Dr. Dater for their willingness to help.

Gemtech MK-9K User Manual (created 1992 and updated in 2015) – https://www.gemtech.com/amfile/file/download/file_id/102/product_id/400/

The MK-9K suppressor is a coaxial design exhibiting increased efficiency as compared to other suppressors of similar external size and ap- pearance. It is designed to mount on the H&K MP5 submachine gun utilizing the HK 3-lug barrel. On special order it can be provided to mount on a 1/2×28 threaded barrel. Suppression efficiency is gained through proper design of the suppressor rather than by using “wipes” or other obstacles touching the bullet in free flight. For this reason, weapon accuracy is not impaired, and accuracy may be actually slightly enhanced by tightening of the group size.

The MK-9K suppressor is a coaxial design unit, consisting of three suppression chambers: the inner rear entrance chamber, the inner front cham- ber, and the outer coaxial chamber. The inner rear chamber diverts pressure into the outer chamber, offering an exceptionally large volume for initial gas pressure reduction, trapping, cooling, and exit delay. The baffle stack (cen- tral core) consists of a steep cone (with a notch in the apex) and a series of precision formed stainless steel baffles. Stainless steel was used for durabil- ity and resistance to gas erosion and corrosion. The baffles are optimally spaced for maximum gas trapping, cooling and delayed gas release into the atmosphere.

The entire suppressor is constructed from hard anodized aircraft grade aluminum alloys with the exception of the baffles in the central core, which are precision formed from type 18-8 stainless steel for wear resistance and durability. No packing materials or consumable parts are utilized.

The MK-9K using the Tri-Lock 3-lug coupler must never be mounted on a 3-lug threaded barrel without a thread protector in place. Failure to observe this caution may result in misalignment. If there is any question, we can provide a suitable thread protector.

GSL Phoenix – Specifications:

The GSL Phoenix suppressor is a full auto-rated, aircraft grade aluminum suppressor that is built to handle your favorite MP5 or Three-Lug Barrel submachine guns. “Rising Out of the Ashes” from a classic design, the Phoenix is back with an incredible sound reduction of 40dB and our updated baffle system. The Phoenix is serviceable suppressor and mounts with our Tri-Lock system.

• Caliber: 9mm
• Sound Reduction: 40 dB
• Length: 8.75″
• Diameter: 2″
• Weight: 18.2 oz.
• Materials: Aluminum/Stainless
• Finish: Hard Coat Anodize
• Mount: Tri-Lock
• MSRP: $850
• Product Page: https://gsltechnology.com/product/the-phoenix/
• User Manual: https://gsltechnology.com/wp-content/uploads/2019/05/GSL-Phoenix-Suppressor-Manual.pdf
• Note: There is a 1/2×28 version for those hosts that are not three lug friendly.

The Phoenix Suppressor is an upgraded version of the classic MK-9K Suppressor. The original MK-9K was a co-axial design, utilizing stamped washers and spacers. The Phoenix Suppressor maintains this co-axial design. The upgraded machine cones and make this unit much more efficient than its predecessor. The Phoenix Suppressor is designed for the Heckler and Koh MP5 sub-machine gun. It should never be used on a center fire rifle.

The Phoenix Suppressor, like its predecessor, is a co-axial design. It has a central core along with the outer core as an expansion chamber. Unlike its predecessor, the Phoenix Suppressor has a series of machined and jetted M-Baffles, which are more efficient than the stamped baffles and spacers that were used in the past models. The baffles are keyed with notches and tangs to maintain the proper alignment of the jetting, giving the suppressor optimum performance.

Disassembly/Assembly:

Luckily I was able to contain my excitement long enough to take apart the Phoenix while it was still clean. As noted above, the Phoenix uses two end caps to sandwich the inner core with the outer tube. For disassembly, unscrew the front cap from the outer tube.

Then unscrew the rear cap from the inter tube exposing the blast chamber and baffle.

To reassemble the Phoenix, follow the steps in reverse.

Removing the baffles is not recommended for routine cleaning so I’m going to wait until I get a few thousand rounds through it before removing the retaining ring holding the stack in place.

Shooting the GSL Phoenix:

The Phoenix was built around the MP5 platform, so since the H&K SP5 dropped a few months ago, I consider this setup destiny. But I also wanted to use another host and silencer combination as a comparison. For me, the B&T APC9 with the TP9 silencer and three lug mount was the perfect contender. Here’s the details of the testing:

• Host: H&K SP5
  • Silencer: GSL Phoenix
  • Ammo: 147gr JHP
• Host: B&T APC9
  • Silencer: GSL Phoenix
  • Ammo: 147gr JHP
• Host: B&T APC9
  • Silencer: B&T TP9
  • Ammo: 147gr JHP

Unfortunately I have a very early manufacture date TP9 three lug mount that doesn’t fit on the H&K SP5, so I couldn’t compare the one host with both silencers.

Both the APC9 and the SP5 were very quiet with the GSL Phoenix, with a subtle but obvious edge going to the SP5. The APC9/TP9 vs SP5/Phoenix competition wasn’t exactly fair, but I’d still give the GSL can the nod for noise reduction with subsonic ammunition.

Conclusions:

For ultimate quiet on a 9mm subgun or pistol caliber carbine, there is no match for the GSL Phoenix in my opinion. However, that title comes at the cost of length, diameter and a bit of extra weight. If you have a full auto MP5 or utilize a binary trigger, I’d seek out the Phoenix and not look back. Semiautomatic users seeking jaw-dropping quietness with subsonic ammunition should also hop aboard the GSL train. As long as you take into account the Phoenix’s weights and measures, you won’t be disappointed.

Have a great week everyone and we’ll see you here next week for another edition of TFB’s Silencer Saturday.

Silencer Saturday is Sponsored by Yankee Hill Machine:

Buy YHM silencers and accessories at:

Silencer Shop – Hansohn BrOthers – dead eye gun supply –

Mac tactical

All YHM Products At Brownells

DEALERS: If you want your link to buy YHM suppressors included in future Silencer Saturday posts, email: silencers@thefirearmblog.com

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special Thanks: Mac Tactical

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