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Folding Firepower: B&T KH9 Covert [Hands-On Review]

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Everyone loves a folding subgun. If it’s not the kid in Robocop 2 with a blue DEB M21, then it’s an old SHOT video of Magpul’s Drake Clark snapping out the FMG-9. At one point, we’d have declared the heyday of these to be in ’80s action movies, but nay, that time is actually right now. Folding guns have always been cool, but now they’re more numerous, much better, and more practical.

The latest comes from B&T — the KH9 Covert. And like any Swiss company, B&T does it with both style and panache. The official story is the KH9 Covert was developed to be part of a pilot Escape and Evasion kit; it could only be so big or else it wouldn’t fit. The real story underpins the name itself: KH stands for “Karl’s Hobby.” Karl Brügger himself says, “I just like the idea of a folding magazine and a folding handgrip that will turn a 9mm carbine into the most compact package available. When I was a young boy, I saw the film Lost Command with Anthony Quinn and all the legionaries had the SMGs with the folding magazine, and I thought that I just had to have one.”

Simply put, the KH9 Covert was going to be made anyway, but rather than being a hobby, it found a home inside ejection seats.


The closed-bolt blowback action itself comes from B&T’s original KH9, produced in 2015.

Most 21st century designs have a forward charging handle along either side of the receiver, but in order to deal with some very specific width requirements, B&T decided to go over the top. This not only solved the issue of minimizing its footprint but also ensured that the Covert 9 was fully ambidextrous. The charging handle, or rather knob, is reminiscent of the Israeli Uzi, providing a throwback feel to this otherwise modern machine.

The bolt lock is also located on the top of the receiver, and while ambidextrous, it’s not exactly an easy reach. The bolt of the KH9 Covert can still be locked back with one hand, but it takes a little practice to do well. It doesn’t lock back on an empty magazine; while this is a non-starter on a rifle like an AR-15, we’d argue it falls into the “nice to have” category for pistol-caliber carbines.

Interestingly, the KH9 Covert has a double-action/single-action trigger; it’s not just an AR-15 trigger shoved into a PCC. In the normal course of operations, when the charging handle is racked an internal striking mass is locked back — think of it like a hammer going back on a DA/SA pistol like a Beretta M9. With the release of the trigger, this block is released and hits the firing pin, making the gun fire. The safety selectors are mirrored, and this model has safe, fire, and a decocker. Yes, a decocker like the Italian Spectre M4 subgun of yesteryear.

Some models of the KH9 dispense with a “safe” position entirely, allowing the much heavier double-action trigger pull to serve against negligent discharge. And we really mean much, much heavier — while the single-action pull consistently broke right around two pounds, the double-action pull was completely off our scale, which maxes out at 13 pounds.

As a neat additional feature, the KH9 Covert has a small indicator on the left side of the receiver to let you know if the striking mass is locked to the rear or not. If it’s showing green, you’ve got a double-action trigger to pull.

While some KH9 Covert models don’t have accessory mounting capabilities beyond the Picatinny rails on the top and bottom, this one features one full and two half M-LOK slots on the sides of the stubby handguard.


The most eye-catching aspect of the KH9 is the ability to fold its own extremities down tight. Everything is based around having an incredibly tight profile while still being quick to deploy. The pistol grip swings back and out of place by depressing a button on the left side, and the magazine well folds forward by pushing a latch snugged into the rear of the magwell. The buttstock can simply be pulled out. Folding it back up takes a little more time, but presumably you’ll only be doing that when all the action is complete.

While all APC9 magazines are functional with the KH9 Covert, B&T made a special magazine specifically for when it’s in the stored position. As a 25-round magazine instead of a full 30, it’s already shorter, but B&T went a step further. This customized magazine also has a shaved spine, intentionally allowing the magazine to be over-inserted into the magwell when folded for additional space savings. To put the magazine in the stowage position, with the magwell folded simply insert the magazine until it locks, and then depress the release to allow it to move a few inches more. Now the magazine will sit no further forward than the three-lug adapter on the muzzle.

B&T designed the magazine to float in this position, so all you have to do to make it ready is swing the magwell back into place; the magazine slides down to the locked position as the locking mechanism clicks it all together — no buttons to press or latches to muck with.

Because the latch is located in a position where many rock ’n’ lock subguns would normally have a magazine release, it was important that the latch be both subdued and have to be pulled rearward. B&T really showcases their experience with human processing here. And indeed, a couple times on the range, perhaps because there was a CZ Scorpion out at the same time, we attempted to grab the latch instead of hitting the push-button mag release. Rather than folding up the whole mess, our brain farts resulted only in a tinge of embarrassment and a split second of lost time before hitting the proper release.

The FAB AGS-43 folding pistol grip has been around for a well over a decade, finding itself on many compact weapons. Worthy of note is the M4-based GAU-5A ASDW (Aircrew Self-Defense Weapon) that has been riding in ACES II ejection seats in F-22 Raptors since 2018 (see RECOIL Issue 61).

If we’re being totally honest, like a lot of Israeli polymer, the FAB pistol grip itself feels kind of cheap in the hand, but it’s hard to argue with success.

Like the magwell, there’s no lock keeping the pistol grip folded other than friction. The result is a grip that stays in place when folded but can quickly be brought into service simply by swinging it down — and then it locks solidly into place.

For right-handers, the push button rests naturally below the thumb of the shooting hand, and for those used to riding the AR safety selector with their thumb, it can be confusing under pressure until you have some rounds downrange. Because the folding mechanism requires the combined actions of pushing it in and swinging the grip back at the same time, this error won’t cause the grip to inadvertently collapse. Still, we’d recommend moving it to the right side to avoid this issue entirely, or perhaps further recess the button into the pistol grip.

We’ve had plenty of experience with the collapsible PDW stock on the KH9 Covert. No, you won’t want to cheek it, but it’s fast and stable while providing an extremely low profile. Like the magwell and grip, there are no locks or latches that need to be pushed, depressed, or mucked with to extend — just pull and it locks out as far as you want it. To collapse the stock, there’s a centrally located button at the rear of the receiver; simply push and slide the stock.

With just a modicum of practice, you can take the KH9 from fully folded to rounds downrange in just a second or two. Not too bad, especially compared to the weirdo folding guns of the 1980s.


Because the KH9 Covert has such a small profile, it fits into all number of bags and cases that don’t scream “gun!” At around 17 by 1.75 by 5 inches in its smallest configuration, we’re sure there’s something already in your house or garage a KH9 could be stashed in.

The bag provided isn’t a large backpack slathered in multicam and MOLLE, but instead it’s a relatively small sling-back. While Wolf Grey is certainly the new FDE which is the new black, so-called tactical bags are far from the only ones using that colorway. Based on materials and construction, we have a pretty good idea of who made these, but with no overt manufacturer labeling — in fact, no labeling at all — there’s nothing stopping you from adding your own flourishes to further increase the camouflage.

The back of the sling bag and the sling itself are lined with a soft-padded mesh, especially nice on hot summer days. The smooth YKK zippers feature black Rescue Essentials T-pulls, which are both easy to find and manipulate even if you’re wearing gloves.

The main compartment has a soft, tight loop for fastening, and there are two thick elastic bands with hooks on the ends to secure the KH9 and ensure it doesn’t flop around. Inside the bag itself, a full 30-rounder fits in the magwell when folded, despite its lack of over-insertion ability.

The smaller zippered front pocket features an admin insert and can accommodate several full mags plus a silencer and other odds and ends.

While wearing it, the only gun anyone would suspect the bearer has is a pistol — and even then they’d be looking for that in the waistline.


Even though our example of the KH9 Covert didn’t come with a manual or official documentation, it wasn’t hard to figure out how to take everything apart. Two pins hold the trigger module in place (sound familiar?). Once removed, the collapsible stock can be pushed down and off the receiver. Tilt the receiver and some of the guts come out, revealing an endcap housing and two springs, one mainspring and the other for the striking mass, as well as the striking mass itself. When the charging knob is in the rearmost position, it can simply be lifted out of place, letting the bolt slide free. Installation is the opposite.

You can also break out a Torx driver if you want to further take down the KH9 Covert, perhaps to swap a handguard, but it’s unneeded for the normal course of maintenance.


Three-lug mounts have been the golden standard for quickly attaching silencers to subguns from just about the moment Dr. Phil Dater (see RECOIL Issue 42) thought it up. The B&T 9mm RBS9 SQD (Reduced Back Pressure, Super Quick Disconnect) Compact silencer paired with the KH9 doesn’t seem terribly remarkable at first blush; at 6.75 inches long, there are a lot of silencers with similar dimensions on the market. Until you get to the attachment method, and then shoot it. Designed to be taken on and off in total darkness with only one hand, to mount the RBS9 SQD Compact you simply push it on the muzzle and it clicks in place. To take it off, press the large, serrated button and pull it off. Now, this isn’t a totally foolproof system, as it’s possible to have a false attachment if you’re between lugs, but you can check for this by simply trying to pull off the RBS9 without depressing the button. This is similar to tugging on the bottom of an AR magazine after seating a fresh mag to ensure it’s fully secure.

While the locking button can be positioned over any of the three lugs, for consistency and ambidextrous use B&T recommends you orient it at 12 o’clock.


Our KH9 Covert came complete with an Aimpoint Acro P2 riding in a BT212353 QD mount. The Acro seems appropriate, as it’s the update to the B&T exclusive Aimpoint Nano. Also included was a pair of folding sights, themselves too tall to be useful with the Acro.

We removed the BUIS, and instead used the front top Picatinny space to mount a SureFire X300T-B Turbo light upside down (commonly referred to as a “Rhino Configuration”). The X300T-B has an output of 650 lumens, but importantly produces a tight 66,000 candela beam for taking shots at beyond subgun distances. For comparison’s sake, the 1,000 lumen X300U has a beam pattern with 11,300 candela.


The recoil of the KH9 is about what you’d expect from a blowback gun this small; more than you may initially think (especially if you’re used to the B&T APC 9K) but certainly manageable. We miss the hydraulic buffer system of the B&T APC 9K here. The recoil springs are rather hefty, and you can feel them while cycling. A vertical grip can help, and indeed there’s a six-slot Picatinny rail up front where one could be installed — but then you’d be negating one of the major sales points of the KH9, namely the ability to fold the magwell and go hot in a split second.

We did manage to find some ammunition the KH9 Covert didn’t particularly like: coated Federal Syntech 150-grain ammunition. Not every gun likes truncated cones, and this KH9 Covert seems to be among them. We also tested a grab bag of rando ammunition, which included everything from underpowered Tula, horrible lacquered Brown Bear, and Winchester white box, to the latest defensive loads from Norma and Federal. The KH9 Covert gobbled them up without complaint, sans one dud primer that hadn’t an iota to do with the gun itself. It should be stated that while the KH9 Covert proved it can eat cheap ammunition, it definitely wasn’t designed for that use case. It’ll always run better and more smoothly with ammunition designed with subguns in mind: 124-grain +P.


Sometimes a gun seems destined for the big screen, and the B&T KH9 Covert certainly has all the required cool points. When it comes to movie guns, looking cool is the only rule — but the KH9 Covert also has all of the mindful precision engineering we’ve come to expect from B&T. It’ll be fitting when that happens, coming full circle for a young Karl Brügger watching Lost Command.

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