CZ-USA Scorpion EVO Unique Bullpup Conversion Kit

For better or worse, I am a child of the eighties. That means I grew up watching sci-fi action movies from that era, and back then there was no more futuristic-looking rifle than the bullpup — a rifle where the trigger group sits forward of the action and magazine, drastically shortening the overall length of the gun. Kyle Reese’s plasma rifle in his flashbacks to the future in The Terminator (1984) is a Valmet M82 bullpup. Most everyone in Total Recall (1990), including Douglas Quaid (Arnold), uses bullpupperized (I just made that word up) Ruger AC556s. This is a full auto version of the Mini-14, set into a Muzzlelite MZ14 polymer bullpup stock.

Currently, you’d be hard-pressed to find a more science-fiction looking firearm on the market than the CZ Scorpion EVO, either in carbine or pistol form. From the factory it looks like a prop from Battlestar Galactica. But that, apparently, wasn’t enough. Cue the ‘80’s action movie music. Manticore Arms loves bullpup rifles. They got their start making accessories (often improved over the original designs) for bullpup rifles including the Steyr AUG and IWI Tavor. In addition to expanding their own offerings to other designs (AR, AK, CZ BREN) they’ve become a go-to design house/skunkworks for many other manufacturers. They make a number of parts used in SB Tactical arm braces. They designed a hybrid magazine for the Scorpion EVO which incorporates steel feed lips. And now they’ve designed an ingenious bullpup kit for the CZ Scorpion EVO which CZ USA itself now offers through their website. I obtained a new CZ Scorpion EVO carbine and one of the bullpup conversion kits from CZ USA. Let’s look at the Scorpion itself first, then dive into the bullpup kit.

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When I use the term CZ Scorpion, I’m of course referencing the new CZ Scorpion EVO. The original Skorpion machine pistol, officially the Skorpion vz. 61, was chambered in .32 ACP, and its design was finalized in 1961. It is an icon of the Cold War era, but very dated. The completely new Scorpion EVO 3 A1 was introduced in 2009, and this submachine gun has been very successful. In 2014 CZ USA announced they would be importing semi-auto (S1) versions of the select fire (A1) SMG, and I was one of the first people standing in line. Technically this is the CZ Scorpion EVO 3 S1 Carbine. EVO 3 for third generation, and S1 for semi-auto. Chambered in 9mm, this carbine features a 16.2-inch barrel. There is a version where the barrel is tipped with a muzzle brake, but the model sent to me has a barrel enclosed by a faux suppressor. Both brake and fake can models are available in black or flat dark earth (FDE).

The carbine is supplied with two 20-round magazines, and CZ sells 30-round magazines as well, which are standard for the SMG. Personally, I don’t think the piece looks right unless it’s got a 30-rounder locked in place. Magazines are polymer, translucent, reliable, and inexpensive. A brief related aside: I competed at the 2019 USPSA Michigan State Championship. I was surprised just how many of my fellow shooters chose to compete in PCC (pistol caliber carbine) division. “What PCC would you recommend for a new shooter, someone just getting into the game?” I was asked at that match by one of my fellow squadmates. Many of the local competitors have known me for years, if not decades, since before I became a gunwriter, and they know I get to test out far more cool guns than the average shooter.

“CZ Scorpion,” I replied without hesitation. “As long as you don’t mind the weird sci-fi looks, it’s one hundred percent reliable out of the box, is less expensive than most of the AR-pattern PCCs, and you can swap out just about every part on the gun other than the receiver and barrel with 1.5- and 3-mm punches and wrenches. And the aftermarket upgrades are inexpensive too.” The entire receiver of the Scorpion EVO is a polymer shell. In fact, the rear of the receiver is two polymer halves which are connected by screws. Initially, I wasn’t sure how to react to its construction. A screwed-together polymer shell? This may sound cheap or disposable, but in fact it is neither. Remember, the EVO was originally designed as an SMG, and it is currently fielded by military and police forces in at least eight countries.

It took me a while to realize that the Scorpion is the modern equivalent of the Sten SMG in that it is made as efficiently and simply as possible to do its job — it’s just made using modern materials and manufacturing techniques. And as modular as the AR platform is, the Scorpion puts it to shame — I’ll repeat myself, you can replace just about every part on the gun other than the barrel and receiver with 1.5- and 3-mm punches and hex wrenches. I know, because I’ve done it, and the number of companies offering upgraded aftermarket parts for the Scorpion is surprising. CZ first offered the Scorpion in pistol form, and I liked my test gun so much I bought it. Whether you’re talking the Scorpion in pistol or carbine form, the internal design and external controls are identical.

This is a straight blowback design. The entire frame of the Scorpion is fiber-reinforced polymer, and a significant portion of the weight of the gun, whether you’re talking carbine or pistol, is in the bolt. Roughly 25% of the carbine’s weight resides in the bolt. As a result, the recoil impulse of the carbine is unusual —there isn’t muzzle rise when you fire; rather, the entire gun jumps in your hand and then settles back down. A heavy bolt is pretty common with blowback firearms as that mass is needed to soak up the recoil impulse of the igniting cartridge. However, all of that bolt weight is in the middle of the gun, and total travel during the recoil cycle is barely two inches. Shooting it I found that the Scorpion didn’t really have any muzzle rise. Instead, the entire weapon seemed to jump up/back upon firing and then go back down.

I’ve fired a full-auto conversion of the Scorpion EVO belonging to Mark Krebs of Krebs Custom, and the recoil pattern was very interesting. On full-auto the muzzle didn’t rise, the gun just jumped up and down in my hands — just like when shooting semi-auto, but a bit faster…. The charging handle of the Scorpion will be in a familiar place for anyone who has handled an MP5: on the left side, forward. Unlike the MP5, though, the bolt of the Scorpion locks back on an empty magazine. And get this — the charging handle is reversible, and switching it to the right side is a very quick and simple process. The safety lever is polymer and bilateral. The magazine release is a serrated polymer paddle on either side of the front of the trigger guard. Move it forward to drop the magazine. It is possible to push the magazine release with your trigger finger. I’d recommend stripping the empty magazine out with your left hand, as your left thumb sits right on the magazine release as you grab the magazine (they tend to not drop free when empty).

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The bolt catch is a very large serrated steel lever on the left side of the weapon above and slightly to the rear of the magazine well. After seating a fresh magazine into the mag well just pull down on the mag catch with your thumb to chamber a new round. Initially, both Scorpion carbines and pistols were topped with proprietary fixed iron sights, but CZ has now gone to Magpul flip-up sights on the carbines. It’s a rare person who isn’t running an optic of some sort these days, but I appreciate that CZ still equips the Scorpion with backup sights. The polymer handguard features M-LOK attachment slots for all your accessory mounting needs. The entire top of the carbine features an uninterrupted MIL-STD-1913 “picatinny” rail. Yes, the rail is polymer as opposed to aluminum, but this is a 9mm carbine, not a long-distance rifle.

The carbine features the same folding adjustable stock as seen on the original SMG. It is a polymer piece with a three-position adjustable LOP from 12–14". It has a smooth rubber buttpad. Press the large button on the left side of the stock near the receiver and it folds to the right. The stock itself is polymer, but the lockup on the folding latch is all aluminum. The carbine can be fired with the stock folded, although I’m not sure why you’d want to, other than to look cool. I have put a lot of rounds downrange through Scorpion EVOs, and have owned a pistol version since 2015, so that should tell you how I feel about the design. They run and run and run. The only issue I have is with the slightly unfriendly controls — the charging handle is a bit too short, trigger pull is too heavy, the right side of the safety lever pokes my finger when I shoot, and the pistol grip is both slick and features an oddly aggressive angle.

However, the great thing about the Scorpion design is that if you want to upgrade it, using just punches and hex wrenches you can swap out every part on the gun but the barrel in minutes, and the multitude of aftermarket parts available for it (extended charging handles, redesigned safety levers, pistol grips, etc.) are very affordable. For example, the HB Industries reduced power spring kit costs just nine dollars and with fifteen minutes of work brought the trigger pull on my personal Scorpion pistol from nine pounds down to five. You read that right, nine dollars. Now let’s get to the bullpup kit, which is also available from CZ USA for $399.

I reached out to Sven Jonsson, President of Manticore Arms, about how the bullpup kit came into being. “We pitched the concept to CZ,” he told me. “They liked the idea and had us develop it, with their input, for them to manufacture and sell. They own the tooling, and we license the design to them under contract. It’s not a typical relationship in the modern firearms industry.” The bullpup conversion kit works whether you have the faux suppressor model like my carbine or the model with the bare barrel tipped with a brake. The size of the bullpup conversion kit surprised me. Everything in the kit fit into a narrow box not much bigger than what you’d see for a long AR-15 handguard. Inside the kit you get all the conversion parts, four hex wrenches, as well as an instruction manual how to convert your carbine.

There’s no grinding or welding or gluing, all disassembly and assembly is accomplished with the use of wrenches and punches and perhaps the judicious use of a nylon hammer. Every wrench you might need to use is provided with the kit, however you’ll need to bring your own screwdriver as a pry bar, a punch or two, and that nylon/brass gunsmith hammer for a few roll pins, among other things. The disassembly and reassembly instructions are four full pages of print (no photos or illustrations) so I won’t be going through them all here, but in short:

To start, take the magazine out and lock the bolt back. Push out the disassembly pin, and your lower receiver will come off your carbine. Fold the stock, and you’ll see the button to remove it (push the button and the stock slides off, it’s that easy). This is not just a simple drop-in conversion kit. You have to disassemble the lower receiver of your gun and take parts from it and install them on the new lower receiver, along with some of the new parts provided for the new lower receiver. You’ll be taking the trigger pack out of your lower, the ejector and bolt assemblies, and taking the trigger shoe off the trigger bar. In fact, you’ll be removing every part from that polymer lower receiver, and installing most of them in the new bullpup lower.

At the front of the instruction manual there are two very large exploded drawings showing all the parts of the standard carbine and bullpup carbine, with the parts numbered, and those parts and numbers are heavily referenced during the build. A lot of my build time was taken up looking back and forth between instructions and diagrams, making sure I was grabbing the right part. The only issue I had initially was the instruction manual not specifically indicating when you were grabbing an old part or a new part, such as when it was time to install the magazine release on the provided lower of the bullpup receiver, but if you pay attention to the part numbers you quickly learn anything over 84 is a new part.

• Helpful hint #1 — you’ll be removing a lot of small parts from the lower receiver, including pins and springs. Get a container for them, as you’ll be reusing some of them. Also, remember which pin/spring is which because you’ll need to reinstall a few.
• Helpful hint #2 — the ejector retaining screw is part screw and part pin. Unscrew it until it spins in place, but then you’ll likely have to pull it out using tweezers or needle nose pliers. Make sure you hold onto the ejector as you’re doing this, as it is under spring tension.

You’ll attach your old trigger shoe to the new trigger bar, which is a flat piece of steel nearly a foot long that sits on the bottom of the bullpup lower receiver and slides back and forth. In fact, it’s that long reach between trigger and fire control system that is the bane of most bullpup rifles, usually resulting in heavy trigger pulls (but we’ll get to that). With this bullpup build you don’t have to worry about the ergonomic disaster that is the factory safety selector. A new steel slider/pushbutton safety is provided for the bullpup, and it moves left and right above the pistol grip. When on “safe” it physically blocks the trigger bar from moving.

The cheekpiece is just about the last piece to install, and it keeps your face off the polymer rail at the rear of the rifle. It includes a brass deflector, but still CZ does not recommend this bullpup conversion for left-handed shooters, as you might end up eating flying cases. Honestly, this is true for most bullpup designs, they put the ejection port right near your face if you’re a lefty. Total assembly time, taking my time, going slowly and carefully, was ninety minutes. But, after having done it once, I could do it again in half that time, now that I know what goes where and why.

Other than using the wrong size screw twice (an error quickly spotted) I made no mistakes, and if I can do it, anyone can do it. That said, I’ve taken apart Scorpions before and was familiar with their receiver parts. When in doubt, take ‘before’ photos. Now for the stats — the standard carbine from the factory weighed exactly seven pounds with an empty magazine in place. The center of gravity was at the front of the magazine well. With the stock extended it was 34.75-inches long, and with it folded it was 24.5-inches long. Trigger pull was 8.5-pounds (which is on par with most Scorpions).

With the bullpup conversion installed, total empty weight of the carbine with an empty magazine in place was seven pounds 12 ounces. The carbine was 26.5-inches long. The center of gravity was an inch forward of the magazine well, so roughly in the middle of the gun. That spot seems a natural place for you to carry the bullpup as your hand fits between the pistol grip and magazine well nicely. In bullpup form, the trigger pull increased to 11.75 pounds, which didn’t surprise me at all. In addition to adding one more part to the fire control system, that part is a long heavy piece of steel that slides along the bottom of the receiver. Most bullpup rifles have trigger pulls nearly double what their contemporaries do. Bullpupperizing the Scorpion makes a bad trigger even worse.

That said…one upgrade I did to my personal scorpion was the “$9 trigger job”. Simply replacing a spring in the fire control unit dropped my trigger pull from nine pounds down to five, without sacrificing reliability. This trigger spring kit is available through HBindustries.net. Swapping this spring out as you did the bullpup conversion would only be a little bit more work. You could also swap out the trigger shoe at that point of the build if you didn’t like the provided stepped polymer model (I prefer a flat aluminum model myself).

One issue I noted was the charging handle. On the standard carbine it is not large. On the bullpup conversion, between the rail riser and the cheekpiece, it almost disappears when locked back. I highly recommend buying one of the extended charging handles on the market — they’re inexpensive and install in seconds with just a punch. The factory pistol grip has quite an aggressive angle, and as a result it is somewhat close to the magazine when you’ve got a 30-rounder inserted. Aftermarket grips will still fit on the bullpup model, and have a more vertical grip angle, so keep them in mind. Part of the bullpup kit is a riser for optics. With that riser you can low-mount red dots directly to it. For part of my testing I removed the riser and mounted an EOTech HWS to the original factory rail on the Scorpion. It was not too low for my face, but I have a narrow face, so your experience may differ.

Bullpups are shorter than traditional designs, and put the weight in closer to your body, making them a bit quicker and easier to transition between targets. The CZ Scorpion bullpup is nearly as short as the standard carbine with the stock folded. However, that distance (and long linkage) between trigger and hammer almost always results in a heavier trigger pull, as seen with this Scorpion. Between the extra weight and moving the reciprocating weight further back in the gun, into the “stock” which is wedged against your shoulder, felt recoil in the bullpup is significantly reduced. I didn’t think the bullpup conversion would do anything to affect the accuracy of the carbine, but just in case I fired groups with it before and after, with no meaningful difference. What difference I saw I attributed to the change in trigger pull.

When I mentioned I was doing this build someone on my Facebook feed stated he thought bullpups were a dead-end design idea. I don’t necessarily agree, and responded “I feel the same way about revolvers, but yet people still buy them…” While not as common, bullpup rifles are still being fielded by armies around the world, including the Steyr AUG, British SA-80, IWI Tavor, and the Chinese QBU-88 and QBZ-95. Being able to turn your Scorpion into a bullpup at home is a neat option. The standard Scorpion has quite an exotic appearance. I don’t know if the bullpup conversion gives it more of a sci-fi look but it is definitely more unusual. Bullpups generally offer advantages over standard designs (length, balance), as well as disadvantages (heavier trigger pull, slower reload), but always have very distinctive features. You have to decide if a bullpup conversion for your Scorpion EVO is right for you.

CZ-USA Scorpion EVO Specs

• Type: Semi-auto, straight-blowback-operated
• Caliber: 9mm
• Barrel Length: 16.2 in CHF
• Receiver: Fiber-reinforced polumer
• Muzzle Device: Faux suppressor
• Overall Length: 34.75 in (extended), 24.5 in. (folded)
• Height: 9.4 in. 
• Weight: 7 lbs. 
• Safety: Bilateral manual
• Magazine Type: CZ 20, 30 rds. 
• Sights: Magpul flip-up MBUS
• Trigger: 8.5 lbs. (tested)
• Accessories: Two 20-rd mags, sight adjustment tool, cleaning kit
• MSRP: $1,116
• Manufacturer: CZ-USA
• Conversion Kit: Manticore Arms

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About the Author

James Tarr is a longtime contributor to Firearms News and other firearms publications. A former police officer he is a USPSA Production Division Grand Master. He is also the author of several books, including CARNIVORE, which was featured on The O’Reilly Factor. His current best-selling novel, Dogsoldiers, is available now through Amazon.

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