US20060027225A1

US20060027225A1 - Firearm simulation device

Info

Publication number: US20060027225A1
Application number: US10/533,739
Authority: US
Inventors: Alexander Homsky
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-11-06
Filing date: 2003-11-06
Publication date: 2006-02-09
Also published as: AU2003282335A1; IL152679A0; WO2004051177A1

Abstract

A method and apparatus for simulating the cycle and recoil of a firearm. The apparatus and method comprising, firearm device (10) which includes a source of compressed gas (11), mechanism (12) configured to release gas from the source of compressed gas, and a piston (14) configured to respond to the force of the compressed gas. Preferably, the firearm device of the present invention features a barrel (13), a magazine (15), a firing pin (16), a chamber (18) for readily accommodating a piston, a piston (14) and a plurality of vents (20).

Description

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to a firearm device. In particular, it concerns a firearm device featuring a barrel unit and a piston unit, wherein the piston unit is accommodated by the barrel unit. Moreover the present invention of a firearm, which employs compressed air to simulate cycle and recoil.
Firearm simulators have wide use in training systems, which are configured to train personnel in the proper use, judgment, safety, and accuracy in utilizing firearms and in simulation games.
The background art describes a variety of firearm devices and firearm cartridges, which includes U.S. Pat. Nos. 5,962,805, 5,842,300, 6,095,051 and 6,253,682.
U.S. Pat. No. 5,962,805 discloses a cartridge, which has a case comprising a body housed telescopically within a sleeve. The body encloses a main chamber, which contains gas under pressure, and a valve mechanism for venting gas from the chamber into an expansion chamber. The pressure of the gas in the expansion chamber causes the body to displace rearward relatively to the sleeve to apply a force to the breech block of the weapon in which the cartridge is used, thereby to initiate the reloading cycle. Gas is vented from the expansion chamber to eject a projectile when a spigot projecting from the body is withdrawn from an aperture in the end wall of the sleeve.
U.S. Pat. No. 6,095,051 discloses a cartridge for use in a firearm, the cartridge having a projectile mounted in or on a nose portion thereof, the cartridge interior communicating with the projectile via a gas passage, a valve for controlling propellant gas flow through the gas passage, and a movable member, which upon firing is propelled rearward from the cartridge against a breech block of the firearm by the pressure of propellant gas within the cartridge so as to recycle the firearm; characterized in that the valve is arranged to close in order to stop or substantially reduce the flow of propellant gas through the said gas passage after the projectile has been fired from the cartridge, thereby to facilitate rearwards propulsion of the movable member.
U.S. Pat. No. 6,253,682 discloses a cartridge comprising a casing having a passage extending there through. A core member is slidably received in the passage, and has a forwardly facing piston surface and a portion closing the forward length of passage in the inactivated condition of the cartridge. A cavity within the core member receives propellant gas from a primer and discharges the gas into the passage forwardly of the piston surface. The core is propelled rearward and releases propellant gas into the forward passage section.
U.S. Pat. No. 5,842,300 describes a retrofittable laser system with which a user can convert his/her own personal firearm to a training firearm simulator incapable of firing live ammunition and then convert back to the original operational firearm configuration. More particularly, the present invention relates to retrofittable laser system, which is integrally mounted within a standard barrel of the laser simulator barrel and electronic means firearm having power mountable in a retrofittable ammunition magazine. An optional recoil means may also be incorporated into the retrofittable barrel and/or retrofittable ammunition magazine.
Disadvantages associated with the simulation firearm devices of the background art include high cost of bullets and the need to replace the bullets, due to wear and tear. The background art does not provide a firearm device, whereby the piston is part of the barrel. Such a device as in the present invention provides a mechanism, which can use compressed gas or fluid to simulate cycle and recoil of a weapon, which can be used indefinitely and is less costly than using bullets.
There is therefore a need for a firearm device, such as disclosed in the present invention. Such a firearm device provides a solution to the problems of costly bullets and slow magazine change, which are associated with simulation firearm devices of the art.

SUMMARY OF THE INVENTION

The present invention relates to a firearm device. In particular, it concerns a firearm device featuring a barrel unit and a piston unit, wherein the piston unit is accommodated by the barrel unit. Moreover the present invention is of a firearm, which employs compressed gas to simulate cycle and recoil.
In a first embodiment the present invention provides a firearm device including (a) a source of compressed gas; (b) a mechanism for releasing the source of compressed gas; and (c) a piston configured to readily facilitate cycling the piston's response to force of the compressed gas.
In a second embodiment the present invention provides a firearm device including (a) a replaceable source of compressed gas; and (b) a barrel including (i) a chamber for containing a piston; (ii) a piston for receiving the compressed gas source and for cycling the action; (iii) a primer simulator, and (iv) a firing pin for readily facilitating striking the primer simulator, the firing pin connected to the piston.
In a third embodiment the present invention provides a method of firing a firearm device including the steps of; (a) providing a firearm device, wherein the firearm device includes (i) a source of compressed gas; (ii) a mechanism for releasing the source of compressed gas; and (iii) a piston configured to readily facilitate cycling the piston's response to force of the compressed gas; and (b) pulling trigger of the firearm device readily facilitating the following steps (i) striking by firing pin of a primer simulator; (ii) releasing of compressed gas from a magazine containing the compressed gas into the piston; (iii) cycling and recoil of the piston resulting from pressure of the compressed gas; and (iv) releasing of the compressed gas from the piston.
In a preferred embodiment the compressed gas is air.
In a preferred embodiment the firearm device further includes a magazine. Preferably the magazine contains the source of compressed gas.
In a preferred embodiment the magazine includes at least one gas pipe.
In a preferred embodiment the firearm device further includes a chamber for containing the piston.
In a preferred embodiment the piston includes (a) a plurality of vents for readily facilitating compressed gas to flow into the piston from the chamber for containing the piston; (b) a plurality of gas outlets for releasing the compressed gas; and (c) a shoulder for readily preventing the piston from being ejected.
In a more preferred embodiment the piston includes (a) a left side of piston, which is smaller than the chamber aperture; (b) a plurality of gas feelers; and (c) at least one gas inlet configured to readily facilitate gas flow from the magazine containing the source of compressed gas.
In a preferred embodiment the pressure of the compressed gas in the piston is from about 150 atmospheres to about 200 atmospheres.
In a preferred embodiment the pressure of the compressed gas in the piston displaces a slide.
In a preferred embodiment the at least one gas pipe readily facilitates flow of the compressed gas source into the chamber for containing the piston.
In a preferred embodiment the mechanism for releasing the source of compressed gas includes (a) a primer simulator located at one end of the chamber for containing the piston; (b) a firing pin configured to readily facilitate striking of the primer simulator and releasing of the source of compressed gas; and (c) an gas pipe configured to release source of compressed gas from the magazine.
In a preferred embodiment the firing pin is selected from the group consisting of internal firing pin, external firing pin or a combination thereof.
In a preferred embodiment the firearm device is for use in combination with any firearm.
In a preferred embodiment the firearm device is reusable.
In a preferred embodiment the firearm device is for use n firearm simulation training.
In a preferred embodiment the source of compressed gas is replaceable.
In a preferred embodiment the firearm device further includes a trigger.
In a preferred embodiment the firearm device further includes (a) a duct; and (b) a disc with hole. Preferably, the piston includes (a) a proximal piston end, which is proximal to duct and which is smaller than the chamber aperture; (b) a plurality of gas sealers to prevent gas escaping; and (c) at least one gas inlet hole configured to readily facilitate gas flow from the magazine containing the source of compressed gas. Preferably, the mechanism for releasing the source of compressed gas includes (a) a primer simulator located at an extremity of the piston; (b) a firing pin configured to readily facilitate striking of the primer simulator and releasing of the source of compressed gas; (c) an gas pipe configured to release source of compressed gas from the magazine to the chamber; and (d) an gas inlet in the piston for gas to flow from the chamber into the piston.
In a fourth embodiment the present invention provides a firearm device including (a) a hydraulic source of compressed fluid; (b) a mechanism for releasing the source of compressed fluid; and (c) a hydraulic piston configured to readily facilitate cycling the piston's response to force of the compressed fluid. Preferably, the fluid is water. In a preferred embodiment the mechanism for releasing the source of compressed fluid includes (a) a primer simulator located at one end of a chamber for containing the piston; (b) a firing pin configured to readily facilitate striking of the primer simulator and releasing of the source of compressed fluid; and (c) an actuator for readily displacing the firing pin, such that the primer simulator simulates the action of a primer.
The term ‘compressed gas’ as used herein, includes but is not limited to gas at a higher pressure than atmospheric pressure.
The term ‘gas’ as used herein, includes, but is not limited to any suitable gas or combination of gases, including, but not limited to air, nitrogen, oxygen, argon and carbon dioxide. Preferably, the term ‘gas’ as used herein is air.
The term ‘piston’ as used herein includes but is not limited to a cylindrical element that slides to and fro in a hollow container.
The term ‘magazine’ as used herein, includes, but is not limited to a case, usually metal for holding cartridges, ammunition, or any other cartridge simulation element employed in firearms. The term includes integral magazines and replaceable magazines.
The term ‘slide’ as used herein, includes, but is not limited to a firearm element, which displaces back along a surface as a result of the firearm being used.
The term ‘firing pin’ as used herein, includes, but is not limited to an elongated metallic element for readily displacing and/or impacting a primer and/or primer simulator.
The term ‘primer simulator’ as used herein, includes, but is not limited to an element, which when hit initiates the firing process of the firearm causing the compressed gas to flow out of the magazine. The term includes affecting an initial input to set a process going
The term ‘cycling’ as used herein, includes, but is not limited to an action of a weapon, such that the weapon performs at least one cycle of loading and firing.
The term ‘recoil’ as used herein, includes, but is not limited to the action of the firearm jerking backwards, as a result of firing of the firearm

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein:
FIG. 1 shows a schematic view of a first embodiment of the firearm device of the present invention;
FIG. 2 shows a schematic view of the piston of a first embodiment of the present invention;
FIG. 3 shows a schematic view of a second embodiment of the firearm of the present invention; and
FIG. 4 shows a schematic cross section of the piston mechanism of a preferred embodiment of the firearm of the present invention;
FIG. 5 shows a schematic view of a preferred embodiment of the present invention before the firearm is fired; and
FIG. 6 shows a schematic view of a preferred embodiment of the present invention after the firearm has been fired.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to a firearm device. In particular, it concerns a firearm device featuring a barrel unit and a piston unit, wherein the piston unit is accommodated by the barrel unit. Moreover the present invention is of a firearm, which employs compressed gas to simulate cycle and recoil.
The firearm device of the present invention is geared towards a multiplicity of different users including, but not limited to the police force, army, security groups and firearm sportsmen.
The principles and operation of a firearm device, according to the present invention may be better understood with reference to the drawings and the accompanying description. The figures are not limiting.
FIG. 1 shows a schematic view of a first embodiment of the firearm device of the present invention 10. As can be see in FIG. 1, firearm device 10 includes a source of compressed gas 11, a mechanism 12 configured to release gas from the source of compressed gas, and a piston 14 configured to readily facilitate cycling piston 14 in response to force of the compressed gas. Preferably, firearm device of the present invention 10 features a barrel 13, a magazine 15, a firing pin 16, a chamber 18 for readily accommodating a piston, a piston 14 and a plurality of vents 20.
Preferably, magazine 15 contains source of compressed gas 11. Preferably, source of compressed gas 11 is replaceable. Preferably, compressed gas is compressed air. Preferably, compressed gas 11 replaces the use of live ammunition in the device of the present invention 10. Magazine 15 is made from any suitable material, such as aluminum, steel stainless steel, alloy and the like. Preferably, magazine 15 is reusable and can be reused substantially indefinitely.
Mechanism 12 for releasing gas from source of compressed gas 11 includes a firing pin 16, a primer simulator 21 and a gas pipe 22. Firing pin 16 is made from any suitable material. Preferably, when firing pin 16 strikes primer simulator 21, which is situated at a far end of chamber 18 for readily accommodating piston, compressed gas 11 from magazine 15 flows out of magazine 15 through gas pipe 22.
Compressed gas 11 flows through vents 20 into chamber 18 and into piston 14. Gas pressure builds up in piston 14. Preferably, a pressure of about 150 to about 200 atmospheres is produced. Preferably, the resulting pressure of the compressed gas displaces piston 14 rearward, thereby cycling the action and simulating how a gun with live ammunition works. Preferably, compressed gas 11 is released by at least one gas release valve 28. Optionally, the cycling action can produce a sound or be silent.
The device of the present invention 10 can be made from any regular firearm, by replacing the barrel and magazine with barrel 13 and magazine 15 of the present invention.
The device of the present invention 10 can be used in any type of gun simulation training or maneuver, such as a two sided drill whereby one person can aim and fire a gun at a second person.
In an alternative embodiment, the firearm device of the present invention 10 works using a hydraulic mechanism, whereby compressed gas 11 is replaced with fluid, such as water. Optionally, any firing pin 16 can be used. FIG. 1 shows an external firing pin 16. When firing pin 16 strikes primer simulator 24, which is situated at a far end of chamber 18 for readily accommodating hydraulic piston 14, an actuator (not shown in FIG. 1) readily facilitates flow of fluid from magazine 15 through vents 20 into chamber 18 and into piston 14. Piston 14 is preferably a hydraulic piston. Fluid pressure builds up in piston 14. The resulting pressure of the fluid displaces piston 14 rearward, thereby cycling the action and simulating how a gun with live ammunition works. Optionally, the fluid is released via at least one fluid outlet 28. Optionally, the cycling action can produce a sound or be silent.
FIG. 2 shows a schematic view of a piston 14 of a first embodiment of the firearm device of the present invention 10. As can be see in FIG. 2, piston 14 features a piston body 30. Piston body 30 includes a plurality of vents 20 and gas outlets 28 and a shoulder 32 for readily limiting lateral displacement of piston 14. Preferably, when primer simulator (not shown in FIG. 2) has been struck, gas is pushed out of magazine (not shown in FIG. 2) through plurality of vents 20 into piston 14, which is accommodated by a chamber to accommodate a piston (not shown in FIG. 2). Piston 14 is configured to readily be displaced backwards and forwards. Shoulder 32 prevents piston 14 from being ejected from chamber. Compressed gas is subsequently released from piston 14 by way of gas outlets 28. Body of piston can be made from any suitable material, such as aluminum, steel, stainless steel, tungsten carbide, reinforced carbon fiber, iron and the like.
FIG. 3 shows a schematic view of a second embodiment of the firearm device 40 of the present invention utilizing a hammerless internal firing pin mechanism 49. As can be seen in FIG. 3, firearm device 40 includes a source of compressed gas 45, a mechanism 46 for releasing gas from source of compressed gas, and a piston 47 configured to readily facilitate cycling a slide 58 in response to force of compressed gas 45. Firearm device 40 features a barrel 42, a magazine 44, a firing pin 49, a chamber 48 for readily accommodating a piston, a piston 47, a primer simulator 52 and a plurality of vents 54.
Preferably, magazine 44 contains compressed gas 45. Preferably, source of compressed gas 45 is replaceable. Preferably, compressed gas 45 replaces the use of live ammunition in the device of the present invention 40. Magazine 44 is made from any suitable material. Preferably, magazine 44 is reusable and can be reused indefinitely. More preferably, magazine 44 includes a valve 41 for readily facilitating filling magazine 44 with compressed gas.
Mechanism 46 for releasing source of compressed gas 45 includes a firing pin 49, a primer simulator 52 and a gas pipe 56. Firing pin 49 is made from any suitable material. In the embodiment shown in FIG. 3, firing pin 49 is a hammerless internal firing pin 49. When firing pin 49 strikes primer simulator 52, which is situated at a far end of piston 47, compressed gas 45 from magazine 44 flows through gas pipes 56.
Compressed gas 45 flows via vents 54 into chamber 48 and into piston 47. Pressure builds up in piston 47. Preferably, a pressure of about 150 to about 200 atmospheres is produced. Preferably, the resulting pressure of the compressed gas displaces slide 58 rearward, thereby cycling the action and simulating how a gun with live ammunition works. Preferably, compressed gas 45 is released by at least one gas release valve 60. Optionally, the cycling action can produce a sound or be silent.
The device of the present invention 40 can be made from any regular firearm, by replacing the barrel and magazine with barrel 42 and magazine 44 of the present invention.
The device of the present invention 40 can be used in any type of gun simulation training or maneuver, such a two sided drill, whereby one person can aim and fire a gun at a second person.
In an alternative embodiment, the firearm device of the present invention 40 works using a hydraulic mechanism, whereby the compressed gas is replaced with fluid, such as water. When firing pin 49 strikes primer simulator 52, which is situated at a far end of chamber for readily accommodating hydraulic piston 47, an actuator (not shown in FIG. 3) readily facilitates flow of fluid from magazine 44 through vents 54 into chamber 48 and into piston 47. Fluid pressure builds up in piston 47. The resulting pressure of the fluid displaces slide 58 rearward, thereby cycling the action and simulating how a gun with live ammunition works. The fluid is released via at least one fluid outlet 60. Optionally, the cycling action can produce a sound or be silent
Preferably, the firearm device of the present invention 40 is used by a user in the following way. User activates trigger 62, by any suitable action preferably by pulling trigger 62. Pulled trigger 62 readily facilitates firing pin 49 striking primer simulator 52. Preferably, the action of primer simulator 52 being hit causes flow of gas 45 from magazine 44 through gas pipe 56 into chamber 48 and through vents 54 into piston 47. Gas pressure builds up in piston 47, causing cycling of action and displacement of slide 58 rearward, simulating recoil. Gas 45 escapes from piston 47 through gas outlets 60.
Alternatively, compressed gas 45 readily flows into piston 47 and pulling trigger 62 facilitates piston 47 to be displaced rearwards, thereby displacing slide 58 and cycling an action.
FIG. 4 shows a schematic view of the piston mechanism 70 of a preferred embodiment of the firearm of the present invention. As can be seen in FIG. 4, barrel 72 preferably, includes at least two barrel sections 74 and 76. Preferably, at least two barrel sections 74 and 76 are tapped, wherein preferably, forward barrel section 74 is readily configured to be screwed into chamber barrel section 76.
Forward barrel section 74 includes a duct 78. In a most preferred embodiment, duct 78 has a diameter of about 3 mm to about 5 mm and a length of about 20 mm to about 35 mm. A protrusion 80, which is preferably, attached to or integrally formed with a piston 82 is accommodated by a disc 84 with a hole 86 formed in disc 84 and readily accommodated and situated in adjacency to duct aperture 88 formed at an end of duct 78.
Chamber barrel section 76 features a chamber 90 for readily accommodating a piston 82 and a gas pipe 92, through which gas flows from a magazine containing a source of compressed gas 91.
Optionally, when barrel 72 is unscrewed into two sections 74 and 76, piston mechanism 82 and disc 84 are inserted. Piston mechanism 82 includes a proximal piston end 92, which is proximal to duct 78 and which is larger then chamber aperture 94. Due to the size restriction, piston 82 is unable to displace to the right beyond a certain degree. Preferably, piston end 92 features a shoulder 93. Piston 82 features a plurality of air sealers 96, which are configured to prevent gas escaping. Piston 82 includes at least one hole 97, which is readily restricted by a counter shoulder 95, through which gas, which flows into chamber through gas pipe 92 enters piston 82. Piston 82 further features primer simulator 98, which is located at distal piston end 99, wherein distal piston end 99 is distal in relation to duct 78.
FIG. 5 shows a schematic view of a preferred embodiment of the firearm device 100 of the present invention before the firearm has been fired. As can be seen in FIG. 5 firearm device 100 includes a source of compressed gas 102, a mechanism 104 configured to release the gas 102, and a piston 106 configured to readily facilitate cycling a slide 107 in response to force of the compressed gas 102.
Firearm device of the present invention 100 preferably, features a barrel 108, a magazine 110, a firing pin 11, 2 a chamber 114 for readily accommodating a piston, a piston 106, duct 116 and a trigger 117.
Preferably, magazine 110 contains source of compressed gas 102. Preferably, compressed gas is air. Preferably, source of compressed gas 102 is replaceable. Preferably, compressed gas 102 replaces the use of live ammunition in the device of the present invention 100. Magazine 110 is made from any suitable material. Preferably, magazine 110 is reusable and can be reused substantially indefinitely.
A primer simulator 118, is preferably, attached or integrally formed with piston 106. Preferably, cycling of the mechanism of firearm device of the present invention 100 is initiated when trigger 117 is pulled, thereafter firing pin 112 strikes primer simulator 118, which is situated at a far end of piston 106. Thereafter, air from piston 106 flows against a disc 125. Thus creating a counter force for readily displacing piston 106 and slide 107 rearward. Piston 106 includes a proximal piston end 120, which is proximal to duct 116 and which is larger then chamber aperture 122. Due to the size restriction, piston 106 is unable to displace beyond a certain degree. Preferably, piston end 120 features a shoulder, which is readily restricted by a counter shoulder. Piston 106 features a plurality of air sealers 124, which are configured to prevent gas escaping. Piston 106 is attached to disc 125 with a hole 126, formed in disc 125 for readily accommodating and readily accommodated and situated in adjacency to duct 116.
Mechanism 104 for releasing source of compressed gas 102 includes a gas pipe 127 for gas to freely flow from magazine 110 to chamber 114, at least one air hole 128 in piston 106 facilitated gas to enter and flow through piston 106 and an air outlet 129 in duct for gas to escape out of barrel 108 after firing. Preferably, compressed air freely flows in the preferred embodiment of the invention.
Before trigger 117 is pressed protrusion (not shown in FIG. 5), which is preferably, attached to or integrally formed with piston 106 is accommodated by disc 125 with hole 126. Preferably, a bias 115 applies sufficient force and/or pressure to situate piston 106 substantially against disc 125.
When trigger 117 is pressed, firing pin 112 displaces laterally, striking primer simulator 118 and displaces primer simulator 118 forward.
FIG. 6 shows a schematic view of a preferred embodiment of the firearm device 130 of the present invention after the firearm has been fired. As can be seen in FIG. 6 firearm device 130 includes a source of compressed gas 132, a mechanism 134 configured to release the source of compressed gas 132, and a piston 136 configured to readily facilitate cycling a slide 156 in response to force of the compressed gas 132.
Compressed gas 132, which is flowing through gas pipe 144 between duct 146 and piston 136 flows through hole 148 into piston 136 and a plurality of air sealers 150 attached to piston 136, prevent gas from escaping. After a trigger 138 is pressed, a firing pin 140 displaces laterally, thereby striking a primer simulator 142 and pushing primer simulator 142 forward. Flow of gas in piston 136 pushes against disc 152 with hole 154, which causes a blow back action resulting in piston 136 displacing to the right and slide 156 displacing to the right. Preferably, piston 136 displaces substantially 1 mm to 7 mm, thereafter gas escapes through hole 154 into duct 146 and out of barrel exit 158. Preferably, a bias 159, which is located in adjacency to barrel 160, applies force and/or pressure sufficient to displace slide. 156 back to its original position. Optionally, the cycling action can produce a sound or be silent.
It will be appreciated that the above descriptions are intended only to serve as examples, and that many other embodiments are possible within the spirit and the scope of the present invention.

Claims

1-33. (canceled)

34. A firearm device for simulating operation of a firearm, the device comprising:

(a) a barrel at least partially defining a chamber;

(b) a slide mechanism slidably deployed behind said chamber;

(c) a firing mechanism including a firing pin and a trigger, said firing mechanism being responsive to sliding of said slide mechanism to cock said firing mechanism, and being responsive when cocked to pulling of said trigger to release said firing pin; and

(d) a compressed gas firing simulation arrangement including:

(i) a vessel containing compressed gas, said vessel being in fluid communication with said chamber,

(ii) a piston arrangement slidably deployed in said chamber, and

(iii) a valve arrangement associated with said piston arrangement and deployed to be displaced by impact of said firing pin to open at least one sealing arrangement, thereby causing said compressed gas to drive said piston rearwards to cause recoil of the firearm device.

35. The firearm device of claim 34, wherein said vessel containing compressed gas is located in a replaceable magazine.

36. The firearm device of claim 34, wherein said vessel contains compressed gas at a pressure of at least 150 atmospheres.

37. The firearm device of claim 34, wherein said firing mechanism is an unmodified firing mechanism configured for firing live ammunition.

38. The firearm device of claim 34, wherein said chamber and said piston arrangement include complementary features for limiting a range of motion of said piston arrangement.

39. A method for modifying a firearm configured for firing live ammunition so as to provide a simulated firearm device, the firearm having a firing mechanism including a firing pin, a bullet magazine for containing bullets and a bullet barrel through which the bullets are fired, the method comprising:

(a) replacing the bullet barrel with a barrel assembly including:

(i) a barrel at least partially defining a chamber,

(ii) a piston arrangement slidably deployed in said chamber, and

(iii) a valve arrangement associated with said piston arrangement; and

(b) replacing the bullet magazine with a vessel containing compressed gas, said vessel being in fluid communication with said chamber,

wherein said valve arrangement is deployed to be displaced by impact of the firing pin to open at least one sealing arrangement, thereby causing said compressed gas to drive said piston rearwards to cause recoil of the firearm device.

40. The method of claim 39, wherein said vessel contains compressed gas at a pressure of at least 150 atmospheres.

41. The method of claim 39, wherein said chamber and said piston arrangement include complementary features for limiting a range of motion of said piston arrangement.