Patent Description:
In firearms, usually in semi-automatic or automatic firearms, a gas system is used for the autoloading cycle for loading the cartridge and removing the shells. In the gas system of the firearm, part of pressurized gas from the cartridge being fired is used to power the gas system to extract the spent case and chamber a new cartridge. Energy from the gas is transmitted through gas openings in the barrel of the firearm. This high-pressure gas impinges on a surface such as a piston head to provide motion for unlocking of the action, extraction of the spent case, ejection, cocking of the hammer and loading of a fresh cartridge. A short stroke gas piston operating system is common on modern rifles. It is defined as a gas piston which travels less than the distance of the bolt carrier. The present invention relates to gas systems operating based on the short stroke gas piston.

The gas systems of firearms known from prior art known as fixed gas systems take gas all the time from the barrel as long as there is pressure, which may lead to variations in acceleration to the bolt carrier assembly, which typically causes functional issues (reliability, cycling, feeding, extraction etc.). dependent on loading and type of used cartridge (bullet, powder etc.). In prior art gas system this is usually overcome by using a manually adjustable gas regulator. Disadvantage of the regulator being manual, is that the user can forget to use the regulator for example in stressing situations, which naturally may have technical and/or functional consequences. Especially difficult situation may be caused, when a suppressor is used as then a back-pressure phenomena might be caused and in worst case the firearm malfunctions and/or breaks down. Thus, in these types of firearms typically only one or a few types of ammunition is used.

In patent publication <CIT> is disclosed an autoloader for a gas operated automated firearm, comprising a gas chamber including an inner diameter and constructed and arranged to receive pressurized combustion gas from a gas port of a barrel of the firearm when a round is fired from the firearm; a piston having a piston head in fluid communication with said gas chamber, said piston constructed and arranged to move away from a firing position to actuate at least a portion of a cycle of the firearm when urged by pressurized combustion gas received in said gas chamber and an expansion valve disposed within the gas chamber, the expansion valve constructed and arranged to move along the inner diameter of the gas chamber from a firing position to increase a volume of said gas chamber when pressure in the gas chamber exceeds a threshold level.

In patent publication <CIT> is disclosed a regulator for a gas operated firearm auto loader, comprising a chamber constructed and arranged to receive pressurized combustion gas from a gas port of a barrel of the firearm when a round is fired from the firearm, a piston having a piston head in fluid communication with said chamber, the piston constructed and arranged to move away from a firing position to actuate at least a portion of a cycle of the firearm when urged by pressurized combustion gas received in said chamber, and a throttling valve in fluid communication with said chamber, the throttling valve having a first position in which pressurized combustion gas from the gas port of a barrel of a firearm can flow into the chamber, and a second position in which pressurized combustion gas from the gas port of a barrel of a firearm cannot flow into the chamber, and wherein the throttling valve is configured to move from the first position to the second position when pressure in the chamber exceeds a threshold level.

In patent publication <CIT> is disclosed an automatic firearm having a barrel with a gas port therein and a reciprocating breech operating member, comprising a gas cylinder secured to the barrel in the vicinity of the barrel gas port, said gas cylinder defining a rearwardly opening, cylindrical chamber disposed parallel to the path of movement of said breech operating member, a cylindrical piston slidably and rotatably mounted within said cylinder chamber, said piston having a forwardly opening hollow portion, the rear end of said piston arranged to abut the breech operating member to impart rearward movement thereto, said cylinder having a gas passage therein communicating between the barrel gas port and the interior of said cylinder chamber, said piston having a reduced diameter annular groove on its periphery located in substantial alignment with said gas passage when said piston is in its forward position, said piston having at least ore generally radial hole in said reduced diameter annular groove, communicating with the said hollow portion of said piston.

In patent application publication <CIT> is disclosed a gas operating system for engaging the automatic or semi-automatic action of a small arms weapon, comprising: a gun barrel having a plurality of radial ports and having radial forward and rear stops fixed thereon; a displaceable cylinder with a gas ring block secured thereto, the cylinder having a short stroke between the radial forward and rear stops fixed on the gun barrel; a fixed piston attached coaxial to the gun barrel and having gas block sealing rings at rearward exterior surfaces of the piston; a gas chamber, formed by interior walls of the cylinder and piston and by outer surfaces of the gun barrel, wherein gas tightness of the gas chamber is established by the gas ring block of the cylinder and by the gas blocking sealing rings of the piston, and wherein the gas chamber receives in operation pressurized combustion gas from fired ammunition, the gas entering through the radial ports of the gun barrel; and a single locking nut comprising a threaded flash suppressor, configured to lock the piston over the gun barrel, wherein the rear stop is cylindrical and is threaded axially to the gun barrel so that the rear stop is rotatable to finely adjust the short stroke of the cylinder.

In patent publication <CIT> is disclosed a gas-operated auto-loading shotgun, a gas pressure adjusting device comprising a valve body in the form having a hollow cylinder of small mass and having first and second pressure-receiving surfaces, a guide rod on which the valve body is slideably fitted, a partition wall having a relatively large valve opening with a large-diameter part and a small-diameter part and constituting a valve seat at its rim part around the valve opening, and a spring for continually biasing the valve body toward the valve seat, whereby the valve opening is normally closed by the rear end surfaces of the valve body and the guide rod.

In patent application publication <CIT> is disclosed a semi-automatic shotgun of the type comprising a magazine tube around which a cylinder is situated, the interior of which is in connection with the interior of the barrel and with, in this cylinder and around the magazine tube, on one hand, a piston, which can shift under the effect of a part of the propulsion gases and can cooperate with a sleeve, which is provided with a rod, which is capable to control the assembly of movable parts, and, on the other hand, a regulation or pressure control valve, springs provided for the control of the reverse motion of the sleeve and the regulation valve, which is completely situated in the piston unit.

An object of the present invention is to create a gas system of a firearm by which the above described problems and disadvantages of gas systems known from prior art are eliminated or at least minimized.

Another object of the present invention is to create an improved gas system of a firearm, in which human error caused disadvantages are minimized.

Another object of the present invention is to provide an improved gas system of a firearm, which is not ammunition sensitive.

Yet, another object of the present invention is to provide an improved gas system, in which manual gas adjustment is not needed.

In order to achieve the above objects and those that will come apparent later the gas system of a firearm is characterized by the features of the characterizing part of claim <NUM>.

Dependent claims present advantageous features and embodiments of the invention.

According to the invention the firearm comprises a barrel comprising gas openings, and a gas system, which gas system comprises a gas block, a gas piston, a force transmitter assembly, an indexing part and an indexing counterpart, gas openings, wherein the gas block is fixedly attached to the barrel, the gas piston is positioned by the indexing part, in the gas system gas is configured to pass through the gas opening of the barrel via the gas openings of the gas system into the gas block and to set the gas piston to movement and that in the gas system the gas piston during its movement backwards is configured to close the gas opening of the barrel for a defined time period and the gas piston is not transmitting power/energy from combustion gas to the force transmitter assembly unless the gas openings are closed. Thus, the gas system is connected to the gas of the barrel only during the defined time and the gas system is automatically controlled to prevent unlimited amount of gas entering from the barrel to the gas block. First the gas piston moves back, at the same time shutting the gas openings and finally making contact and transmitting energy/forces to the bolt carrier via the force transmitter assembly.

According to an advantageous feature of the invention the gas system is a short stroke gas piston system.

According to an advantageous feature of the invention the gas block is attached onto the barrel of the firearm.

According to an advantageous feature of the invention the gas block is attached around the barrel of the firearm.

According to the invention the gas system comprises an exhaust opening in the gas block and after a certain period of time the exhaust opening connected to ambient pressure is opened.

According to an advantageous feature of the invention the gas block and the gas piston together form a hollow encapsulation which is filled with gas from barrel.

According to the invention the gas piston is connected via a spring-loaded pin or bushing to at least one force transmitter of the force transmitter assembly.

According to an advantageous feature of the invention the force transmitter assembly comprises a helical return spring, which is configured to function as a return-spring returning the force transmitter assembly and the gas piston to its initial position.

According to the invention the indexing part comprises beveled surfaces and an indexing groove to keep the gas openings of the gas piston aligned with gas openings in the barrel and the gas block.

According to the invention the gas system comprises an indexing counterpart with an indexing protrusion, which corresponds to the indexing groove of the indexing part of the gas piston.

According to an advantageous feature of the invention outer surface of the gas piston is provided with grooves for crust removal.

In this description the terms, back, front, upper, lower etc. are used as reference to the normal position of a firearm, when used for firing. They are not to have any as such limiting effect.

According to the invention in the autoloading cycle, the gas space within the gas block is filled for a determined time, the gas system is configured to close the gas connection between the gas openings of the gas system and the gas opening of the barrel and thus, only a certain, selected amount of gas is let into the gas space within the gas block to create the pressure behind the gas piston.

By the gas system according to the invention and its advantageous features many advantages are achieved: The gas system of the firearm according to the invention has an automatic function principle and thus, there is no need of human input and any disadvantages caused by human error are minimized. The gas system of the firearm according to the invention has a self-regulating function principle and thus, no manual gas adjustment is necessary. In the gas system of the firearm according to the invention the gas system shuts gas opening in the gas block once a specific amount of gas is taken for cycling the firearm. The user can safely operate the firearm with both a suppressor and without a suppressor. Further, the firearm is not ammunition sensitive as the gas system functions well with different kinds of loads. The risk of overloading the firearm system is eliminated and hence long-lifetime for the components (extractor, buffer etc.) is achieved.

In the following the invention and its advantages are explained in greater detail below in the sense of example and with reference to accompanying drawing, where.

During the course of the following description like numbers and signs will be used to identify like elements according to the different views which illustrate the invention and its advantageous examples. In the figures some repetitive reference signs may have been omitted for clarity reasons.

In the <FIG> is shown an example of a firearm <NUM> comprising a barrel <NUM> and gas system <NUM>. The gas system <NUM> operates based on the short stroke gas piston system.

In <FIG> is shown one advantageous embodiment of the gas system according to the invention.

In the example of <FIG> is shown an example of the gas system <NUM> of the firearm <NUM>. The gas system <NUM> comprises a gas block <NUM>, which is attached to a barrel <NUM> of the firearm <NUM> by spiral pins <NUM>, a gas piston <NUM> by which energy of the gas from barrel <NUM> is transmitted to mechanical movement, and a force transmitter assembly <NUM>. The gas block <NUM> and the gas piston <NUM> together form a hollow encapsulation which is filled with gas from barrel <NUM>. The gas piston <NUM> is connected via a spring-loaded pin <NUM> (<FIG>) to a force transmitter <NUM> (<FIG>) of the force transmitter assembly <NUM>. The spring <NUM> providing the spring-loading of the spring-loaded pin <NUM> is denoted by reference <NUM> in <FIG>. The spring-loaded pin <NUM> is first compressed before contact is made to the force transmitter <NUM> of the force transmitter assembly. Once contact is made i.e. the gap <NUM> between the gas piston <NUM> and the force transmitter assembly <NUM> is closed, gas forces transmit to bolt carrier (not shown and cycling process of autoloading starts. Before that no acceleration happens to the bolt carrier assembly and a bolt (not shown) of the bolt carrier stays closed. At this position, the autoloading cycle begins.

In <FIG> is shown an alternative of an assembly of the force transmitter assembly <NUM> comprising a force transmitter <NUM> as an exploded view. The force transmitter assembly <NUM> comprises by the spring <NUM> spring-loaded pin <NUM> at one end of the force transmitter <NUM> of the force transmitter assembly <NUM>. The force transmitter assembly <NUM> also comprises a cotter pin <NUM> and a spring pin <NUM> for fastening the components of the force transmitter assembly as shown in the <FIG>. Further, the force transmitter assembly <NUM> comprises a helical, return spring <NUM>, which functions as a return-spring returning the force transmitter assembly <NUM> back into its initial position independent of bolt carrier movement. The helical, return spring <NUM> is located making contact with a spring bushing <NUM>. The force transmitter assembly <NUM> also comprises a bushing <NUM> for guiding the force transmitter <NUM>.

In <FIG> is shown another alternative of an assembly of the force transmitter assembly <NUM> but instead the spring <NUM> loading the spring-loaded pin <NUM> (<FIG>) at one end of the force transmitter <NUM> of the force transmitter assembly <NUM> the spring <NUM> effects the spring-load to a bushing 14B.

In <FIG> is shown the force transmitter assembly <NUM> in accordance with the example of <FIG> as an assembled view. At one end of the force transmitter <NUM> of the force transmitter assembly <NUM> is the spring-loaded pin <NUM>, which controls movements of the gas piston <NUM>.

In <FIG> is shown in more detail the spring-loaded pin <NUM> of the force transmitter assembly <NUM> in accordance with the example of <FIG>. The spring-loaded pin <NUM>, which controls movements of the gas piston <NUM>, is pressed in, when the gas piston <NUM> makes contact to the force transmitter <NUM>.

In <FIG> is shown in more detail the gas piston <NUM> in accordance with the example of <FIG>. Gas openings <NUM> are located on the gas piston <NUM>. Next to the gas openings <NUM> are located planar surface parts <NUM> for cleaner operation. Outer surface of the gas piston <NUM> is also provided with grooves <NUM> for crust removal. The gas piston <NUM> is provided with an indexing part <NUM> with bevelled surfaces <NUM> and an indexing groove <NUM> to keep the gas openings <NUM> of the gas piston <NUM> aligned with gas openings in the barrel <NUM> and the gas block <NUM>. If this would be in wrong position, no gas could flow into the gas piston <NUM>. The indexing groove <NUM> is to secure the gas piston <NUM> at correct position inside the gas block <NUM>, which moves the gas piston <NUM> that actuates the force transmitter <NUM> included in the force transmitter assembly <NUM>, which at the end pushes a bolt carrier. The force transmitter <NUM> is mounted to an opening <NUM> at one end of the gas piston <NUM>.

In <FIG> is shown in more detail one end of the gas piston <NUM> in accordance with the example of <FIG>. The indexing groove <NUM> for securing the gas piston <NUM> has the beveled surface parts <NUM>.

In <FIG> is shown in more detail front side of the gas piston <NUM> in accordance with the example of <FIG>. As can be seen from the figure the gas piston <NUM> has a tubular form.

In <FIG> is shown in more detail front side of an indexing counterpart <NUM> located below the gas piston <NUM> in accordance with the example of <FIG>. For the indexing part <NUM> the gas system <NUM> comprises thus the indexing counterpart <NUM>. The indexing counterpart <NUM> has an indexing protrusion <NUM>, which corresponds to the indexing groove <NUM> of the indexing part <NUM> of the gas piston <NUM>. A form-fitting joint is formed by the indexing groove <NUM> of the indexing part <NUM> and the indexing protrusion <NUM> of the indexing counterpart <NUM> and thus, the gas piston <NUM> is located at the correct position. The indexing protrusion <NUM> guides by the indexing groove <NUM> the gas piston <NUM> to its correct location.

In <FIG> is shown the force transmitter assembly <NUM> in accordance with the example of <FIG> as an assembled view. In this example the force transmitter assembly <NUM> comprises by the spring <NUM> (<FIG>) spring-loaded bushing 14B at one end of the force transmitter <NUM> of the force transmitter assembly <NUM>. The spring <NUM> effects the spring-load to the bushing 14B. Further, the force transmitter assembly <NUM> comprises the helical, return spring <NUM>, which functions as the return-spring returning the force transmitter assembly <NUM>, when the bolt carrier has returned back. The helical, return spring <NUM> is located at a spring bushing <NUM>. The force transmitter assembly <NUM> also comprises a bushing <NUM> for guiding the force transmitter <NUM>.

In the <FIG> is shown a more detailed example of the outer circumference with crust removal grooves <NUM> of the force transmitter <NUM> of the force transmitter assembly <NUM> in accordance with the example of <FIG>. The spring-loaded bushing 14B does the same function as the spring-loaded pin <NUM>. The spring <NUM> is located inside bushing 14B and is a helical spring and the forces are transmitted using the helical spring <NUM> inside to the force transmitter <NUM>.

In the <FIG> is shown a more detailed example of an example of an end <NUM> of the force transmitter assembly <NUM> in accordance with the example of <FIG>. In this example the end <NUM> of the force transmitter assembly <NUM> is tapered for controlling the position of the force transmitter assembly <NUM> in conjunction with a gas piston <NUM> (<FIG>).

In the <FIG> are shown more detailed examples of further examples for controlling the position of the force transmitter assembly <NUM> by the end <NUM> of the force transmitter assembly <NUM> in accordance with the example of <FIG>. In these examples one end <NUM> of the force transmitter <NUM> is turnable to selected positions.

In <FIG> is shown a more detailed example of an alternative of the indexing part <NUM> of the gas piston <NUM>. The indexing part <NUM> of the gas piston <NUM> has a protrusion <NUM>, which corresponds to the indexing groove <NUM> of the indexing counterpart <NUM> (<FIG>). A form-fitting joint is formed by the indexing groove <NUM> and the indexing protrusion <NUM> and thus, the gas piston <NUM> is located at the correct position. The indexing protrusion <NUM> guides by the indexing groove <NUM> the gas piston <NUM> to its correct location.

In <FIG> is shown the example of <FIG> yet in greater detail. Additionally, in the figure is shown the gas piston <NUM> at the position, where it has travelled to contact the force transmitter <NUM>. In this position no more gas passes from the barrel <NUM> of the firearm <NUM> to the gas piston <NUM> and charging is finished. Only the gas encapsulated inside the gas block/gas piston <NUM> volume is contributing to the cycling of the weapon now.

In <FIG> and <FIG> is shown the example of <FIG>. The press button assembly <NUM> is pressed down and the indexing counterpart <NUM> is unlocked and the gas piston <NUM> is released as shown in <FIG>. The positioning tag <NUM> positions the barrel <NUM> and the gas block <NUM>.

In <FIG> is shown the gas block <NUM> of the gas system <NUM>. Inside the gas block <NUM> a space <NUM> is provided for the gas piston <NUM>. Towards the space <NUM> inside the gas block <NUM> grooving <NUM> is provided for crust removal and gas sealing. At least one bore <NUM> is provided also in the gas block <NUM> for the indexing counterpart <NUM>. Additionally, one exhaust opening <NUM> is provided on the front of the gas block <NUM>. The gas block <NUM> will be attached onto the barrel <NUM> of the firearm <NUM> by attachment means, for example by spiral locking pins <NUM>.

In the following the operation of the gas system <NUM> is described with reference to <FIG> and to the example of the <FIG>.

In <FIG> is shown stage <NUM>, when a shot is fired and the bullet B has not yet reached the gas openings <NUM> and no gas passes yet into the gas block <NUM>. In this stage openings of the gas piston <NUM> are aligned with the gas openings <NUM> and the exhaust opening <NUM> is closed by the gas piston <NUM>. Thus, the gas system <NUM> is still in its initial setting. Once the bullet B passes beyond the first of the gas openings <NUM>, gas will start streaming into the gas block <NUM>. The pressure inside the gas block <NUM> rises and the gas piston <NUM> starts moving, while the bullet B continues its travelling towards the end of the barrel <NUM>. The gas piston <NUM> acts on the bushing 14B or the spring loaded pin <NUM> respectively (<FIG>) integrated into the force transmitter assembly <NUM> (<FIG>, <FIG>) and the force transmitter <NUM> (<FIG>, <FIG>, <FIG>), which do not move at this point and hence do not transmit momentum onto the bolt carrier. At this stage the cycling operation has not yet begun.

In <FIG> is shown stage <NUM>, when the bullet B has reached the end of the barrel <NUM>. The gas piston <NUM> has moved to rest against the force transmitter assembly <NUM> (<FIG>, <FIG>) and the force transmitter <NUM> (<FIG>, <FIG>, <FIG>), which are still stationary and have not yet accelerated the bolt carrier. At this stage no more gas from barrel <NUM> can flow into the gas openings <NUM> and the exhaust opening <NUM> is still closed. Additionally, to the bushing 14B or the spring-loaded pin <NUM> (<FIG>) pressure inside the gas block <NUM> acts onto the bolt carrier by means of the force transmitter assembly <NUM> (<FIG>, <FIG>) and the force transmitter <NUM> (<FIG>, <FIG>, <FIG>). After the bullet B has passed through the end of the barrel <NUM>, movement of the bolt carrier is initiated. As this happens only after the bullet B has left the barrel <NUM>, any harmful vibrations cannot influence accuracy of the trajectory of the bullet B anymore. After this stage, the movement of the bolt carrier will unlock the bolt and finally start the cycling operation, which has altogether been delayed up till this stage.

It should be noted that in the gas operating systems according to prior art the cycling starts immediately once gas reaches the gas piston.

In <FIG> are shown stages <NUM> and <NUM>, when the bullet B is long gone and travels towards its target along its trajectory. In the meantime the pressurized gas enclosed within the internal volume of the gas openings <NUM> has carried out work and by means of the gas piston <NUM> pushed the force transmitter assembly <NUM> (<FIG>, <FIG>) and the force transmitter <NUM> (<FIG>, <FIG>, <FIG>) backwards for a certain distance and therewith transmitted momentum to the bolt carrier. The force transmitter assembly <NUM> (<FIG>, <FIG>), the force transmitter <NUM> (<FIG>, <FIG>, <FIG>) and the gas piston <NUM> stop at some point and the bolt carrier and the bolt continues moving on its own in accordance to "the short-stroke system"- principle. Shortly before the gas piston <NUM> reaches its rest position after having accelerated the bolt and the bolt carrier, the exhaust opening <NUM> is opened. At this point the still pressurized working gas inside the gas block <NUM> is streaming through the exhaust opening <NUM> forward away from the shooter and the gas is released to the environment. The openings of the gas piston <NUM> are still shut so that no remaining combustion gases can flow into the gas block <NUM> through the gas openings <NUM>. After the pressure inside the gas block <NUM> has sunk sufficiently, the spring-actuated force transmitter assembly <NUM> including the force transmitter <NUM> and the spring-loaded bushing <NUM>, 14B will together with the gas piston <NUM> return into their initial position i.e. stage <NUM> shown in <FIG>.

It should be noted that in the above description referring to the <FIG> the operation of the gas system <NUM> has been explained in view of an example comprising two gas openings <NUM>. The gas system <NUM> can comprise one or more gas openings <NUM>.

In <FIG> is shown one embodiment of the gas system. The example of the <FIG> is not covered by the subject-matter of the claims.

In the example of <FIG> is shown another example of a gas system <NUM> of the firearm <NUM>. The gas system <NUM> is located around the barrel <NUM> of the firearm <NUM>.

In <FIG> is shown as an exploded view the example of <FIG> of the gas system <NUM> located around the barrel <NUM> of the firearm <NUM>. The gas system <NUM> comprises a gas block <NUM>, a gas piston <NUM> by which the energy of the gas is transmitted to mechanical movement inside the gas block <NUM>, an indexing part <NUM> and a force transmitter assembly <NUM>. A force transmitter assembly comprises a sleeve <NUM>, an extension part <NUM> with spring (not shown), spring-loaded pins <NUM> with springs <NUM> and guide pin <NUM> for keeping the gas openings in gas piston <NUM> and barrel <NUM> aligned.

In <FIG> is shown the gas block <NUM> of the example of <FIG>.

In <FIG> is shown the gas piston <NUM> of the example of <FIG>, <FIG>.

In <FIG> is shown the force transmitter assembly <NUM> of the example of the <FIG>, <FIG>. A force transmitter assembly comprises a sleeve <NUM>, an extension part <NUM> with a spring (not shown), spring-loaded pins <NUM> with springs <NUM> and a guide pin <NUM>.

In <FIG> is shown the force transmitter assembly <NUM> of the example of the <FIG> in greater detail. The force transmitter sleeve <NUM> comprises three pins <NUM>, which are spring-loaded with springs <NUM> and one guide pin <NUM>.

In <FIG> is shown the force transmitter extension part <NUM> and the indexing part <NUM> of the example of the <FIG>.

In the following the operation of the gas system <NUM> is described with reference to <FIG> and to the example of the <FIG> not covered by the subject matter of the claims but it should be noted that the examples presented in <FIG> operate correspondingly by substantially same functions and basis. In <FIG> is shown the basic situation and in <FIG> the situation, when the gas piston <NUM> and spring-loaded pins <NUM> move and in <FIG> the situation, when the gas piston <NUM> and the force transmitter assembly <NUM> move.

The gas block <NUM> and the indexing part <NUM> are not moving parts but instead stay at their locations. In the basic situation the force transmitter assembly <NUM> has pushed the gas piston <NUM> to its front position and thus, the spring-loaded pins <NUM> have pushed the gas piston <NUM> to its front position and the gas can flow through the gas openings <NUM> to the space in between the gas piston <NUM> and the gas block <NUM>. Pressure of the gas in the space between the gas piston <NUM> and the gas block <NUM> moves the gas piston <NUM> and from the gas opening <NUM> no further gas can enter the space between the gas piston <NUM> and the gas block <NUM>. The spring-loaded pins <NUM> of the force transmitter sleeve <NUM> have been pressed in to pressed position. When the pressure of the gas between the gas piston <NUM> and the gas block <NUM> has moved the force transmitter assembly <NUM> against the indexing part <NUM> the gas can flow off through the openings <NUM> in the gas block <NUM>. At the end, the force transmitter assembly <NUM> and the gas piston <NUM> are pushed to the front position and the spring-loaded pins <NUM> push the gas sleeve to its front position and the gas system <NUM> is back in the basic situation.

Claim 1:
Firearm (<NUM>) comprising a barrel (<NUM>) comprising a gas opening, and a gas system (<NUM>), which gas system (<NUM>) comprises a gas block (<NUM>), a gas piston (<NUM>), a force transmitter assembly (<NUM>) comprising at least one force transmitter (<NUM>), gas openings (<NUM>) located on the gas piston (<NUM>), which gas block (<NUM>) is fixedly attached to the barrel (<NUM>), in which gas system (<NUM>) gas is configured to pass through the gas opening of the barrel (<NUM>) via the gas openings (<NUM>) of the gas system into the gas block (<NUM>) and to set the gas piston (<NUM>) to movement, in which gas system (<NUM>) the gas piston (<NUM>) during its movement backwards is configured to close the gas opening of the barrel (<NUM>) for a defined time period and that the gas piston (<NUM>) is not transmitting power/energy from combustion gas to the force transmitter assembly (<NUM>) unless the gas openings (<NUM>) of the gas system (<NUM>) are closed, which gas system (<NUM>) comprises an exhaust opening (<NUM>) in the gas block (<NUM>) and after a certain period of time the exhaust opening (<NUM>) connected to ambient pressure is opened, characterized in that the gas system (<NUM>) comprises an indexing part (<NUM>) comprising beveled surfaces (<NUM>) and an indexing groove (<NUM>), and an indexing counterpart (<NUM>) with an indexing protrusion (<NUM>) corresponding to the indexing groove (<NUM>) of the indexing part (<NUM>) of the gas piston (<NUM>), to keep the gas openings (<NUM>) of the gas piston (<NUM>) aligned with gas openings in the barrel (<NUM>) and the gas block (<NUM>), and wherein the gas piston (<NUM>) is positioned by the indexing part (<NUM>), and that the gas piston (<NUM>) is connected via a spring-loaded pin or bushing (<NUM>; 14B) to at least one force transmitter (<NUM>) of the force transmitter assembly (<NUM>).