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Enhancing The APC9K: Ultimate Sub Gun?

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When the APC9K replaced the MP5K in various arms rooms, it signified a shift that Hemingway aficionados would identify as the painful death of the old world for a newer, more contemporary operating style. 

Of the many terms used in gun culture, “Manual of Arms” has either not yet seated its place in common vernacular, or it has already passed from one peak, waiting for the next occasion to arrive in regular use. 

Whether in competition shooting, personal defense, or military application, if a firearm’s layout inhibits the user’s experience, it will typically take second place to an alternative with better controls. In this fashion, Lingle Industries took an already rising platform of the APC/GHM from B&T, improving the weakest points in an already strong design.

When the APC challenged the H&K MP5, it did so by addressing the aging, but beloved firearm’s weak points: manual of arms and maintenance. For those of us who grew up almost entirely on Americanized AR-15 style controls, the Euro-style safety selector and fixed grip angle didn’t leave much room for the end-user to make adjustments to their liking. 

Without a flared magwell, and having no bolt release built into the lower, the MP5 relied on three aging factors: nostalgia, institutional use, and slapping the charging handle. However, once the jokes and dopamine wear off, the younger, curvier features of the APC9 start to look damn good. Add to all of this the availability of each in the American market, and you have yourselves a recipe for gun culture regicide.

Despite having features that the MP5 was lacking — rail space out of the box, a free floated barrel, and a flared magwell — arguably the most painful aspect of the APC9 and similar platforms are the magazines. 

Aesthetics aside, B&T magazines are neither the cheapest, nor the most enduring, when they arrive from Switzerland. Do they run well? Yes. Do they mind being dropped on concrete? Half say no. 

One of the downsides to more compact subguns is their lack of rail space once you start adding accessories.

Lingle Industries, which specializes in producing aluminum lowers for various firearms such as the SCAR (both big and small), B&T platforms, the CZ Bren-2, and the Stribog, have improved upon the already enjoyable APC9K providing compatibility with  CZ Scorpion magazines, even more AR-15-like controls, and the user’s choice of AR-15 grip and trigger group. 

While B&T has released pro-series lowers for the APC and GHM lines of firearms that can use proprietary, Glock, or SIG P320 magazines depending on model, there’s something about Scorpion magazines that go beyond just aesthetic appeal.

The CZ Scorpion has been around for more than a decade, despite not gaining American attention until around 2015. Since then, we’ve seen various upgrade kits, accessories, and arguments for and against its viability in various scenarios. One testament to its success, however, is when Magpul released not only a 35-round curved box magazine, but a 50-round drum for the Czech pistol-caliber carbine. 

Got a favorite AR grip that you just can’t live without? Lingle has you covered.

With a Lingle Industries lower, both the GHM and APC9K can utilize the reliability of Magpul’s EV9 curvy stick mags and their 50-round drum designed for the Scorpion Evo-3. In addition, the user can install their own trigger, with a limited list of exceptions. Add your choice of safety selector and pistol grip, and you’re good to go with a sturdy aluminum lower for an already reliable firearm.


Out of the box, the lower arrives with the bolt and magazine releases installed, the former in similar fashion to the original APC but with a Strike Industries paddle release 

subbed in to accommodate Scorpion mags. Constructed out of 7075 aluminum billet, it feels sturdy, with a choice between a tan or black Cerakote finish. Don’t worry about having to purchase yet another lower parts kit to complete installation with that spare AR-15 safety selector rolling around in the junk bin — selector spring and detent are included. If you chose to purchase a new set of lower takedown pins and their retaining springs, go ahead. We cannibalized them from the original lower. 

When matched to an APC upper, there’s a little bit of play, but Lingle Industries included a tensioner in their lower to take out that slack. With a fairly flared magwell that improves on the APC about as much as the APC improves on the MP5, it’s easy to swap, slap, and jam mags into place and begin the next course of fire. 


From installation, the ability to choose a grip and trigger launched us on a journey of enjoyable discovery. While the PCC craze has largely slowed from its heyday, we decided to rig up a duty gun instead of a full-blown competition bullet hose. Take the APC9K, add a suppressor by JK Armament, drop the side-scales of M1913 Picatinny, top with optics and a light, and you’re good to go for everything from high-speed varmint eradication to home defense. 

Since magazines carry much of the weight of ensuring reliability in a firearm, with the steadfast history of the Magpul EV9, the remaining factor had to be the lower. After roughly 1,000 rounds and no stoppages, with only a single wipe-down in between, the Lingle Industries lower kept feeding rounds steadily into the APC6K upper through both the box and drum mag options. 

Ergonomically, the drum felt a little wonky, forcing an exaggerated forward hand placement. It felt more like a trade-off, Call of Duty style, gaining capacity at the cost of some reload speed and maneuverability ­­­— but not by much. Having the option is great, even if it’s not the preferred configuration for every situation. 

Instead of going straight for the most gritty of duty-grade triggers, the Hiperfire Enhanced Duty Designated Marksman Trigger added the touch of control we wanted to bump the already operator-feeling firearm to the next level. Why it seems every duty-style trigger needs to be grinding through over 5 pounds of press to crack the shot should be investigated for bureaucratic oversight. 


 The APC9K already made a name for itself when it unseated the king of sub guns. But that doesn’t leave it closed for improvement, as the Lingle lower has shown. Even if/when B&T drops a second version of their 9mm magazine, the reliability and availability of Scorpion Evo-style magazines is going to be hard to beat. 

Does this improvement justify spending additional cash just to get a new lower for an already respectable platform? Various agents who regularly field the APC and GHM believe so. If magazines alone don’t do it for you, there’s nearly the entire gambit of trigger-selector-pistol grip combinations that push the rugged lower into a better place. 

At the start of this article, we mentioned the manual of arms. While we’re giving up the AR-15 style magazine release, the paddle-release has undergone many enhancements since the knuckle-cutting days of the early MP5 or even AK-style Soviet ingenuity. The familiarity of AR-15 controls between the grip, trigger, and safety selector greatly reduces the time necessary to become competent with another firearm, and the compact size, in this case, does add to the usability of the gun. 

So, when we talk about the manual of arms having an impact on the viability of a firearm, it doesn’t stop at what comes from the OEM. A firearm with reliable magazines, and a familiar and trusted trigger and controls, goes a long way when running it under pressure, be it competition shooting, war, or self defense. 

Any chance we get to improve that experience, without sacrificing reliability, is a win. Lingle Industries delivers this to the APC platform, turning a new champion into a better version of itself. 



  • APC9K: $2,450
  • JK Armament 9mm Suppressor (no longer available) equivalent to a 155 Versax 9mm, with a War Eagle Comp and Flash Hider: $764 + $200 Stamp
  • Burn Proof Gear Suppressor Cover Heavy: $200
  • Inforce WML Gen 2 White/IR: $150
  • Vortex Spark SolAR Red Dot: $150
  • AGM Global SingIR 640: $4,600


  • Lingle Industries APC/GHM Lower: $365
  • Hiperfire Enhanced Duty Trigger Designated Marksman: $100
  • Magpul MOE+ Grip AR-15: $25
  • Magpul Pmag 35 EV9: $20
  • Magpul Pmag D-50 EV9: $130

Total all parts not counting miscellaneous safety selector: $4,354
Plus Tax Stamp $4,554
Plus Thermal: $9,154

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