Crowdfunding Project: SIRCA TEC SLF-X Pisol

SIRCA TEC SLF-X Pisol Project (6)

I learned about this firearm project from a firearms dedicated crowdfunding website called Gun Dynamics. By browsing their website you can find several gun-related campaigns but one of the most significant and interesting projects is definitely the crowdfunding campaign started by a company called Sirca Tec and dedicated to funding a really exciting pistol called SLF-X. Let’s take a closer look at this project.

SIRCA TEC SLF-X Pisol Project (2)

The whole idea behind this project is to design a pistol that would be extremely easy to shoot with as less muzzle climb and felt recoil as possible. According to Sylvio Lorenzut, the designer of this gun, he started thinking about the design of this pistol because his wife and four daughters love to shoot but don’t feel comfortable with handguns chambered in calibers larger than .22LR. I am pretty sure that most of you have encountered such situation where female shooters or shooters with low grip strength or even people that are presented to handgun shooting first time have difficulties with handling the full caliber pistols especially when it comes to making quick successive shots. Even if you have sufficient grip strength it may take some time until you get comfortable with shooting handguns. There are of course exceptions, but generally speaking, the problem that the designer of this pistol is trying to solve does exist.

SIRCA TEC SLF-X Pisol Project (3)

Once you have decided to design a new revolutionary handgun with minimal recoil, it is obvious that you have to employ some unusual, out of the box concepts into the design. And that is what the designer of this pistol did. The whole mechanism of the pistol is different from what we are used to seeing. Let’s first watch one of the videos published on the crowdfunding campaign’s page then discuss the design features of the pistol.

As you can see in the video and according to the description on the crowdfunding campaign’s website, “the SLF-X splits the kinetic energy between two opposing slides which counters muzzle climb“. The front portion of the slide that moves forward upon firing also contains the barrel. By having two reciprocating parts moving in opposite directions you can mitigate a lot of the felt recoil. I think it is safe to say that we are observing a balanced action mechanism employed in the pistol design.

SIRCA TEC SLF-X Pisol Project (11)

Now let’s think about the mechanism of operation of this firearm. Apparently, there are no visible signs of a locked breech. Initially, I was going to speculate with describing a number of possible mechanisms of operation that theoretically can be used in this firearm. However, in order to avoid publishing potentially misleading information, I contacted Mr. Lorenzut and asked him to explain the mechanism of operation. Below I am quoting what the designer of the pistol told me when explaining the mechanism:

The Sirca design is somewhere between a blowback and a delayed blowback in that there is no delaying device other than the dynamics inherent in the mechanism that causes the delay. Upon firing a conventional pistol the barrel is forced back and transfers energy to the slide and initiates recoil. In the Sirca, while the slide (rear) end wants to go rearward, so too does the barrel (front) end. Because the rearward drive of the slide moves the barrel end forward mechanically and there is nowhere for the barrel end to go rearward there is a slight delay in separation until the slide end wins out and separation can begin. This “dwell time” allows gas pressures to drop to a safe level and is the reason for mechanical breechlocking in higher powered calibers.

SIRCA TEC SLF-X Pisol Project (7)

Further research revealed that there is a patent application filed for this project. The number of the application is US20110088304A1 and you can download it by clicking here. Based on the description given in the patent application we can say that the rear moving slide and forward moving slide/barrel assembly are connected to each other via a couple of linking parts that synchronize the motion of the two moving assemblies.

SIRCA TEC SLF-X Pisol Project (1)

Image from the patent application. Note the drawing of the link and directions of its movement

Another interesting design solution is the layout of the recoil spring mechanism. The recoil spring gets sandwiched between the moving assemblies and compressed from either side when the action opens. According to the designer, such layout of the recoil spring provides two advantages. First, it eliminates the recoil spring design drawback of conventional pistols where the recoil spring is compressed against the frame which in its turn transfers that force to the shooter’s hand. Second, two slides compressing the recoil spring from its either side never hit each other or the frame. This is like the constant recoil concept (mostly known to be used in Ultimax LMGs) executed in a very interesting, simple and clever fashion.

SIRCA TEC SLF-X Pisol Project (2)

Drawing of the recoil spring mechanism

The working prototype of the pistol seems to have proven the viability of the concept. The campaign has published a graph showing the stability of the pistol’s muzzle climb compared to conventional 9mm pistols (models are not specified). You can see that graph below.

Interestingly, because of the described mechanism, this pistol has no ejection port per se. However, once the reciprocating parts start moving in opposite directions, they also create quite a large ejection port. Another advantage of such system is that the reciprocating parts have to move half the distance of the conventional pistol slide movement resulting in half the lock time.

Another advantage of this design is the slightly longer barrel at a given overall length (or shorter overall length at a given barrel length) because the barrel extends over the cartridges in the magazine at about half the length of the cartridge.

Other advantages of the pistol include the fully adjustable trigger and the easy field stripping procedure. The overall amount of parts these pistols are made of is 35-38. The Sirca Tec SLF-X pistol is also extremely lightweight weighing only 1.25-1.5 lbs.

SIRCA TEC SLF-X Pisol Project (4)111

The computer mockup of the possible appearance of the final production version of Sirca Tec SLF-X pistol

I think the inconvenience or impossibility of using the front half of the slide to charge the gun can be considered as a drawback of this pistol. In such design, you can’t charge or press check the gun by pulling back the front portion of the slide because that front portion is designed to move forward. You should be able to do a press check by pushing forward the front of the slide but that would be a really awkward motion. This is probably not a terrible issue though. Even if it is an issue, it can be quite simply fixed by attaching a thin-walled extension to the rear slide that would telescope over the front slide/barrel assembly.

SIRCA TEC SLF-X Pisol Project (4)222

Overall, I am really impressed whit Mr. Lorenzut’s work. Nowadays we rarely see new pistols with any new operation mechanism. Not that the good old Browning short recoiling system with a tilting barrel lockup (which the vast majority of modern pistols utilize) is bad, but when you need more from the handgun (better controllability and minimum recoil) you have to use new solutions. Right now the campaign has reached a little over the 10% ($10,530) of the ultimate goal of $100,000. I really hope that the inventor will manage to reach that goal and will be able to bring this incredibly interesting, unusual and cool pistol to the market.

Many thanks to Sylvio Lorenzut and Lawrence Lopata for explaining the concept and providing the information.


Being a lifelong firearms enthusiast, Hrachya always enjoys studying design, technology and history of guns and ammunition. His knowledge of Russian allows him to translate and make Russian/Soviet/Combloc small arms related information available for the English speaking audience. Hrachya also writes for
Should you need to contact him, feel free to shoot him a message at

Gun Dynamics in the Media

Fox Business
wallstreet reporter
baltimore post
Christian Science Monitor