The Low-Recoil Space-Age MARS Rifle

    The Space Age MARS Rifle (1)

    I learned about the MARS rifle right before the SHOT Show 2019. The video demonstration of this rifle on the company’s website showed that while being chambered in .308 Winchester, the rifle virtually has no recoil. Needless to say that I was curious to find the MARS Inc. at the show and see if the gun matches the claims.

    The Space Age MARS Rifle (7)

    Luckily, the company brought the rifle to the range day of SHOT Show 2019 and I was able to fire several rounds. It was really impressive! Not only it does have a low recoil comparable to that of the .223/5.56, but it also recoils differently. Instead of a kick in your shoulder, you feel a push which is so gentle that you start doubting if you are shooting full-power .308 Winchester ammunition.

    The Space Age MARS Rifle (6)

    My next meeting with the MARS Inc. officials was in their booth the next day. They demonstrated some of the internal parts of the rifle and explained how it works. The secret sauce of its low recoil is the mechanism of operation. Here is how it is described on the company’s website:

    At the center of the MARS design is the revolutionary, patented hybrid operating system called the Integrated Piston-Recoil Operating System – IPROS .  IPROS virtually eliminates recoil for high-powered calibers, without the extra weight and bulk of traditional recoil mitigation techniques.

    The Space Age MARS Rifle (4)

    Barrel of the MARS rifle

    In a nutshell, the inventors combined the long barrel recoiling and gas operated actions in a single rifle. As in the case of other long barrel recoiling actions, upon firing the cartridge, the reciprocating parts (BCG and barrel locked together) travel rearward to the full length of the receiver remaining locked. Once this assembly has reached its rearmost position, the action unlocks and the barrel starts moving forward (forced by its return spring) while the BCG is held at its rearmost position. On its way back, the barrel exposes/extracts the fired case allowing it to be ejected. Once the barrel reaches its furthermost position, it releases the BCG which then moves forward chambering a new cartridge and closing the action. In the case of MARS rifle, this mechanism is also boosted by a gas system. There is a gas port drilled in the barrel which vents gasses to the gas chamber in the front portion of the receiver, thus assisting the rearward motion of the barrel. So in this case, the barrel partially works as an op rod.

    The Space Age MARS Rifle (2)

    The Space Age MARS Rifle (3)

    The bolt carrier of MARS rifle

    The gas system basically works as a booster ensuring a reliable action of the system. In fact, the inventor describes this system as a “gas-assist recoil operating system“. The gas system is also adjustable and will allow to fine tune the rifle to achieve minimal recoil and reliable operation with any particular load or in any environmental conditions. The company officials also told me that because the vented gasses also push forward on the static receiver (while pushing the barrel back), it helps to counter the recoil, too. I think the long barrel action is mostly what is responsible for the low recoil and the unusual recoil impulse which as I mentioned earlier feels not as a kick but rather a push. Interestingly, the muzzle brake is not attached to the barrel but it is built into the very front end of the handguard.

    The Space Age MARS Rifle (5)

    On the left, you can see the part that allows adjusting the gas system. On the right is the barrel bushing that guides the barrel inside the receiver during its reciprocating motion.

    To understand this action better, I asked the folks at MARS Inc. booth to tell me the number of the patent awarded for this invention. The MARS rifle design is protected by the US Patent #9921022 which you can view here or download by clicking here (.pdf file). To completely understand this mechanism, I’d highly recommend reading the patent. But if you want to have a general idea, I’ll quote below excerpts from the patent text that I think wrap up the idea behind this rifle.

    A firearm comprising a barrel assembly, forward receiver, and receiver brake. The barrel assembly comprises a barrel, compression spring, gas tube, and front and rear bushings. The gas tube is situated around the barrel between the front and rear bushings and is not attached to the barrel. The compression spring is situated around the barrel between the front and rear bushings and inside of the gas tube. The front and rear bushings are fixedly attached to the forward receiver. The barrel comprises a gas port that is covered by a gas regulator and is in fluid communication with a gas chamber situated between the front bushing and the gas regulator, which is fixedly attached to the barrel. The receiver brake is fixedly attached to the forward receiver on its distal end.
    Until now, recoil operating systems and gas operating systems were considered mutually exclusive or at least independent of one another.
    It is an object of the present invention to provide a firearm operating system that combines the advantages of a recoil operating system with an integrated gas-assist system to eliminate virtually all recoil and significantly improve accuracy.

    MARS Rifle Patent Drawings (1)


    A. Overview

    In semi-automatic firearms, energy is needed to cycle the operating system. The present invention is based on a recoil operating system, which allows the barrel to move in relation to the rest of the firearm and in relation to the shooter. The present invention also incorporates an integrated gas-assist system in which the barrel itself acts as the gas piston.

    Typical modern firearms have fixed barrels, which means that any recoil (as an equal and opposite reaction to the fired projectile) is transferred directly to the receiver and then to the shooter, unless it is reduced by a muzzle brake or an external mechanism. Because muzzle brakes and other external recoil-reducing mechanisms have a limited effect, fixed barrel firearms are ultimately limited in performance as they cannot fire ammunition with high energy output without unacceptable levels of discomfort to the shooter.

    One drawback of recoil operating systems is the possibility of reduced reliability due to differences in the energy balance between the fired round and the operating system demand. These differences may arise because of different ammunition or varying weapon conditions, such as fouling or heating. If the firearm has a fixed energy balance system, then variations in the energy input or output can result in either misfires or excess recoil. The present invention overcomes these disadvantages by incorporating an integrated gas-assist system and receiver brake into a recoil operating system.

    In the present invention, the gas-assist system is similar to a gas-piston operating system (such as is described in some of the prior art examples discussed above) except that it works in conjunction with the recoil system rather than independently of it. The gas-assist system of the present invention uses the barrel, which is already moving as a function of barrel recoil, as the piston and effectively uses the firearm receiver as the piston housing. When barrel recoil does not prove sufficient energy to cycle the action, the gas-assist system provides the rest of the energy needed to do so without increasing any recoil effect on the shooter. Depending on the balance of weight between the moving, operating parts and the stationary firearm receiver, the gas-assist system may in fact reduce the recoil felt by the shooter by pulling the receiver forward during the firing cycle.

    The receiver brake of the present invention functions similarly to a conventional muzzle brake except that the barrel is free to recoil, applying recoil energy to the operating system, while the receiver brake acts on the receiver, pulling it forward to reduce felt recoil at the same moment at which the barrel begins to move rearward. Through the use of appropriate springs, which are described more fully below, the energy of both systems (the recoil system and the gas-assist system) is balanced, and recoil is either completely neutralized or drastically reduced.

    Below you can also find some of the drawings from the patent showing the basic layout of the parts. The numbers in the drawings refer to the following parts: 4-Barrel, 5-Receiver brake, 6-Bracket, 7-Rail, 8-Gas tube, 9-Front bushing, 10-Rear bushing, 11-Compression spring, 12-Gas chamber, 13-Gas port, 14-Gas regulator, 26-Rear bushing, 27-External gas cylinder, 28-Compression spring, 29-Collar, 30-Gas chamber, 31-Gas port, 32 Piston rod.

    MARS Rifle Patent Drawings (2)

    The barrel assembly

    The barrel assembly with the gas tube removed

    MARS Rifle Patent Drawings (4)

    Cross section of the barrel assembly before firing

    MARS Rifle Patent Drawings (6)

    Cross section of the barrel assembly with the barrel on the halfway of its travel distance

    The above-embedded patent drawings represent the long barreled version on the MARS rifle. The patent also shows the layout of parts for the versions of this rifle with mid and short length barrels.

    The patent also describes an alternative version of the parts layout where instead of a barrel spring wrapped around the barrel, there are two separate springs located underneath the barrel as shown in the following drawings.

    MARS Rifle Patent Drawings (8)

    MARS Rifle Patent Drawings (9)

    MARS Rifle Patent Drawings (11)

    MARS Rifle Patent Drawings (13)

    Pretty interesting concept, isn’t it? I was really impressed with the soft recoil of this rifle.

    Nevertheless, there are several things that I am still skeptical about:

    1. How well will the action perform in adverse conditions where the internal parts are exposed to elements? This question can be answered only by extensive testing of the final version of this weapon system.
    2. How easily the rifle can be serviced in the field? If this rifle is considered a potential military firearm, then it has to have a reasonably easy field stripping and malfunction clearing procedures. There are examples of rifles that achieve unmatched results downrange (e.g. AN-94 Abakan) but are a complete nightmare when it comes to disassembling or clearing the malfunctions.
    3. I am quite skeptical about the long-range (or even mid-range) accuracy of the rifle considering that its reciprocating barrel is probably not the best feature for achieving satisfactory results in the accuracy department.

    One could expect the cost of the rifle to be added to the drawbacks/concerns list too, however, I think it is not priced too bad. According to the company officials, the complete rifles, as well as AR-10 lower receiver compatible uppers will be available in June 2019. The MSRP of the upper receiver assembly will be $2,995 and the complete rifle will cost you $3,495. While these are not affordable price tags, they are not too bad for a rifle with such a huge amount of time and R&D invested into it. There are 1911 pistols that cost as much.

    What do you think about the MARS rifle? Sound off in the comments section.

    Hrachya H

    Managing Editor

    Being a lifelong firearms enthusiast, Hrachya always enjoys studying the history and design of guns and ammunition. He also writes for and
    Should you need to contact him, feel free to shoot him a message at [email protected]