Abstract: The invention is a gun mount exerciser to force a cannon through its recoil otion which otherwise occurs only when the cannon is fired. The exerciser includes a frame that rests on the outer casing that is fixed around the cannon. The frame is translated on a stationary member by actuation of a fluidically operated cylinder mounted to the stationary member. The frame is fixed to the outer casing of the gun so that translation of the frame effects translation of the outer casing and the cannon itself.

Abstract: An injection device for fluid propellants for a fluid propellant gun. The device includes at least one pump chamber for receiving a propellant, with one pump piston movable in each pump chamber. A slide is provided for opening and closing apertures in an injector surface which at least partially surrounds the gun's combustion chamber and which is arranged approximately radially to the projectile ejection direction. The slide and pump piston are configured as mutually freely movable components and a mechanism for developing a pressure is provided for displacing the slide by such pressure.

Abstract: An injection device for fluid propellants for a fluid propellant gun includes at least one pump chamber to accommodate a propellant, a pump piston movable therein and a device for the measured opening and closing of apertures in an injector surface disposed at least partially around a combustion chamber of the gun and approximately radially to the direction of ejection of a projectile from the gun. The device for the measured opening and closing of the apertures in the injector surface is composed of a slide provided with passage openings, the slide being relatively movable with respect to the injector surface and being displaceable by a pressure generating device.

Abstract: An interdiction system to be placed upon the floor of the ocean includes a arget detection and classification system which is cooperatively connected to a hollow enclosure containing a predetermined volume at one atmosphere or less pressure. Upon target aquisition and classification, the detection and classification system actuates a mechanism to rupture the wall of the hollow enclosure. The resultant implosion caused by the ambient ocean pressure creates a high intensity shock wave in the vicinity of the system to damage the intruding vessel.

Abstract: A differential pressure piston-combustion chamber system for barreled or tube-firing weapons or guns with a regeneratively-actuated propellant injection device for the generation of propellant gases of liquid, in particular hypergolic propellant components. A differential pressure piston is arranged so as to be axially movably in the weapon housing coaxially relative to the weapon barrel, with the piston incorporating propellant infeed passageways as well as a loading piston which is in communication with filling passageways. In the cylindrical shaft of the differential pressure piston, there is concentrically arranged a charging piston which is movably axially relative thereto, where the free end is in communication with infeed passageways, and the differential pressure piston and the charging piston are provided with control rolls which, respectively, roll along as associated control cam track on a drum controller.

Abstract: An industrial shotgun is provided with a pistol type hand grip assembly, a remote trigger mechanism, and a hanging support bracket at approximately the center of mass of the industrial gun. The remote trigger mechanism includes a remote trigger coupled from the hand grip to the trigger through a horizontal linking bar. The trigger is disengaged from the remote trigger when the breech block is opened. The hand grip includes a dead man safety which prevents remote trigger actuation unless the thumb operated dead man safety is depressed and the breech block is fully closed.

Abstract: A ship or other marine surface vessel to be protected against torpedo or missile attack tows therebehind an articulated train of floating projectile barriers. To defense on attack, the ship circles away from the attacker to a position behind a trailing portion of the floating barrier train. Each floating barrier includes a solid wall, torpedo intercepting keel or hull which is buoyant, horizontally stabilized and supports thereon a missile intercepting fence extending above the surface of the water. Provision is made for drawing projectiles to the floating barriers and for determining the position of the attacker.

Abstract: A versatile, dearmer using small arms cartridges that is low cost, may be usable, and can employ various types of destructive projectiles including water, clay, shot and steel slugs. A novel feature is a shock tube firing circuit which, when combined in a multiple barrel embodiment, produces multiple projectiles with a high degree of firing simultaniety.

Abstract: Fatigue and fracture testing of a larger caliber cannon is accomplished by explosively thermally decomposing within the cannon bore acetylene of 0.27 grams per cc density and repeating this operation a predetermined number of times or until the surface and subsurface portions of the bore exhibit microstruictrual and other changes characteristic of those resulting from actual firing operations.

Abstract: Electrical stunning systems are disclosed which employ one or more electrically conductive ballistic streams for contacting an unauthorized subject to complete an electrical circuit over which is administered the dose of stunning energy. Various sensors sense unauthorized entry and initiate commands and/or delivery of the dose of stunning energy. A volume control limits the amount of conductive liquid dispersed per dose of stunning energy. A continuity detector assures completion of the electrical circuit to the subject before applying the stunning energy. A range finder determines the length of the ballistic stream and adjusts the stunning power to compensate for losses in the ballistic stream. A functional tester tests for and indicates the operational readiness of the system. Viscosity increasing, surfactant and ionic additives to the aqueous solution improve the ballistics, wetting ability and conductivity of the ballistic stream and facilitate, inter alia, clean up of the spent stream material.

Abstract: A blast-resistant container for receiving an explosive or explosive-suspect article comprises a high-strength outer housing, and an inner compressible layer of a mixture including vermiculite in a binder, effective to space the article from the outer housing, to absorb energy of the blast before transmited to the outer housing, to distribute the blast forces over a larger surface area of the outer housing, and to impart resistance to the penetration of fragments to the outer housing.

Abstract: A device performs forwardly oriented case ejection from an externally driven automatic cannon, the cannon having a chamber, a breechblock which is longitudinally movable along a path by the action of a rotating control cylinder and which simultaneously advances an ejecting device for ejecting a cartridge case, and an intermittently rotating rotor having a plurality of rotor pockets disposed circumferentially thereabout for moving a cartridge into the path of the breechblock and for removing a cartridge case from the path of the breechblock, wherein the ejecting device is a case pusher for ejecting empty cartridge cases, the case pusher being coaxially mounted within the rotor for longitudinal movement relative thereto, the case pusher including a plurality of carrier elements projecting radially into respective ones of the rotor pockets; and a connecting arrangement is used for joining the case pusher with the breechblock such that the case pusher is axially displaceable together with the breechblock and the

Abstract: A transmitter coil is located at the muzzle of a firing weapon downstream of a muzzle velocity measuring device as viewed in the flight direction of a projectile after firing. The transmitter coil transmits a digital adjustment signal for inductively adjusting in the projectile during its passage through the transmitter coil, a counter for starting a delayed action fuze in the projectile. The individual digital adjustment signals are constituted by double pulses and a predetermined number such as at least 12 double pulses are transmitted by the transmitter coil to the receiver coil in the projectile. Electronic switches are utilized for controlling the operation of the transmitter coil. A filtering device is connected in circuit with the receiver coil and the counter in the projectile for eliminating interfering pulses which originate from the muzzle velocity measuring device.

Abstract: A bullet trap comprises a lid over a container body holding aggregated, randomly- or not-randomly-arranged swatches of one or more types of polyacrylamide fiber material or the like. The lid is penetrable by bullets and the aggregated swatches slow any bullets which penetrate the lid sufficiently to retain them in the container. The bullet trap is intended for use in a method of safely loading and unloading firearms in which the firearm is aimed at the trap during loading and unloading to trap any bullets accidentally discharged during loading and unloading.

Abstract: In an externally powered firing weapon the danger exists with an ignition delay or hangfire condition that the cartridge still is ignited after the positively reciprocated breechblock has been unlocked from the weapon barrel. The safety apparatus in accordance with the invention prevents, in case of an ignition delay, firing of the cartridge after unlocking of the positively reciprocated breechblock. Heretofore known safety devices of this type are complicated and a substantially simple design is strived for. The safety apparatus in accordance with the invention automatically decouples the breechblock carrier from the breechblock head when the breechblock head is locked in the weapon barrel. The device responding to an ignition delay prevents unlocking of the breechblock head from the weapon barrel and coupling of the breechblock carrier with the breechblock head.

Abstract: For dispersing of rioters, an ammunition is used which includes a plurality of pieces of ice, which preferably, have a spherical shape and are fired at rioters by a firing equipment.

Abstract: An improved ammunition feed and guide mechanism for an automatic gun barrel weapon such as an automatic machine cannon. This mechanism includes a breech mechanism mounted in a housing. The breech mechanism includes a breech body driven by a pair of rollers rotatably mounted in the housing parallel to the middle longitudinal axis of the housing. Each roller has a driving ramp disposed on its periphery and the breech body is provided with a pair of roller bearings respectively engaging the driving ramps of the rollers so that the breech body is linearly reciprocated between loading and firing positions via the rotation of the rollers and the engagement of the roller bearings in the driving ramps thereof. The pair of rollers are driven by means independent of the propulsion energy of the fired projectiles.

Abstract: An externally driven automatic weapon in which the breechblock and the function of supplying cartridges into the cartridge chamber are effected or controlled by means of a rotatably mounted control cylinder which is provided with a camming path on its circumference and which is driven by an external drive arrangement including a motor and gears for connecting the output of the motor to the control cylinder. The motor and the gears for the control cylinder are disposed within the control cylinder, with the motor being connected to a first nonrotatable stub shaft on which one end of the control cylinder is rotatably supported and with a gear housing or gear block for the gears being connected either to the control cylinder or to a further nonrotatable stub shaft on which the other end of the control cylinder is rotatably mounted. Alternatively, the control cylinder itself may be configured as part of an electric motor which serves as the primary drive, e.g., in the form of a barrel-type engine.

Abstract: The method makes it possible to neutralize surface-laid or camouflaged and in particular intelligent land mines, in that a focused beam of a powerful laser unit is automatically or manually systematically guided over the surface to be cleared of land mines in a grid pattern, the movement sequence of the laser beam being program controlled, so that the laser beam in computer-assisted manner locates the laid mines both systematically in the SCAN process and also in planned manner and neutralizes or detonates them by introducing energy.

Abstract: Cylindrically arranged barrels include feeder rods connected to a wobble plate for reciprocally moving shells into a firing position. A back pressure seal sleeve may be positioned on the feeder rods. The sleeves include a forwardly tapering wall thickness whereby combustion pressures press the tapered wall sealingly against the feeder rods. An alternative sealing arrangement includes cut-off pins for each barrel which reciprocate transversely of the barrel in timed relation with the feeder pins. A cam rotates with a power shaft connected to the wobble plate and a nonrotating housing is positioned on the cam and is connected through linkage elements to the cut-off pins.

Abstract: A method and a device for angle coding a guided smooth-tube projectile, by which the roll position existing at the launching can be coded irreversibly for any insertion position of the projectile in the launching tube.

Abstract: A rock breaking tool comprising a firing mechanism and firing chamber for discharging a blank cartridge into an impulse barrel. The impulse barrel has lateral openings and is intended to be inserted into a predrilled water filled hole in rock to be broken up. The barrel has a venturi throat for increasing cartridge discharge gas velocity.

Abstract: This invention provides the provision of a motor, whose output shaft is fixed to a pinion gear, meshed with two mutually opposed driven pinion gears, each carrying a respective cam roller, which alternatively enter and exit a cam surface on a cam follower, which is fixed to a second shaft, to oscillate said follower and said second shaft, and a first sector gear which is fixed to said second shaft and meshed with a second sector gear, which is axially fixed to the rocking lever in the drive linkage of a machine gun. Alternatively, the first sector gear is meshed with a second sector gear formed on the rocking lever.

Abstract: The invention is directed to an automatic firearm apparatus of the type including a feed system and a rotatable drum driven in rotation by an outer motor, wherein the drum includes a closed contour breech drive ramp. The apparatus includes two follower members cooperating with the ramp, each rigidly mounted on a breech to impart to the breech a reciprocating movement between a feed position, in which it is separate from its respective cartridge chamber, and a firing position, in which it closes the cartridge chamber. The feed system includes a feed mechanism rotating continuously and two distribution mechanisms rotating intermittently. Each of the distribution mechanisms are arranged to receive ammunition from the feed mechanism when stopped and, when rotating thereafter, to supply this ammunition to its respective breech while the latter is in its feed position.

Abstract: This invention provides the provision of a machine gun having a pair of gun barrels fixed to the receiver with a pair of operating mechanism driven by a rocking lever and each operating mechanism including a reciprocating slider which drives a reciprocating gun bolt assembly and a forward stripper which also serves to lock the gun bolt assembly.

Abstract: An arrangement for rapidly stopping the movable parts of machine cannons with independent external drives wherein a rotating element, which rotates in dependence to a rotating control drum drivingly connected to the breech block, is stopped at misfiring or delayed firing within the breech block locking period of the firing cycle by a locking element which is actuated by propellant charge gas pressure. The arrangement of the invention prevents a shock-like braking and transfer of the kinetic energy of the movable parts of the machine cannon and provides for an automatic release of the blocking element.The arrangement includes a rotating rod spring coaxially mounted within the control drum by means of which the kinetic energy of the rotating masses of the breech drive are elastically braked.

Abstract: A device for allowing a 25 mm or similar gun to be cycled through its automatic or semi-automatic mode without live ammunition and without interrupting each cycle because of a misfire. The device is entirely electric and requires no mechanical attachments to the gun and no adjustments of the gun. The device is portable and can be quickly and easily connected to and disconnected from the gun. The device uses signals from a source of gun control signals to develop a sear solenoid voltage which simulates signals developed by gun recoil caused by live ammunition. The simulated signals enable the gun to operate without stopping due to a misfire.

Abstract: This invention relates to an arrangement for rapidly stopping an automatic weapon having an external drive where the breech block is driven by parallel shafts. This arrangement provides for the rapid stopping of the shafts and thus the weapon by providing the shafts with coaxially mounted pockets at their ends in which a pair of claws may be engaged to stop the rotation of the shafts.

Abstract: In a Gatling gun containing a rotary weapon barrel assembly and positively reciprocating breechblocks, each of which is operatively associated with one weapon barrel of the weapon barrel assembly, each breechblock is provided with a spring-loaded firing pin and a cocking pin which are cocked and released by two control cams for piercing a cartridge. These two control cams are displaced from a safety or unarmed position into a firing position by a control slide possessing oppositely extending control grooves or slots. This firing apparatus possesses no pivotable parts as opposed to known apparatuses.

Abstract: A method for effectuating the acceleration of an object, in particular a piercing or penetrator object, within a surrounding liquid medium of a density which is higher than the density of gases, such as in water; as well as an arrangement for producing and imparting an advancing or propelling force to an object in a surrounding liquid medium of a density which is higher than the density of gases; and in particular to an obejct which is to be driven into a water bottom or seabed.

Abstract: A safety device for preventing an airborne charge (1) from being armed prior to being dropped, said charge being armed by a draw wire (4) connected to the aircraft applying traction to an arming cable (3) connected to the charge. The safety device comprises a clamping assembly (2) through which the arming cable (2) passes freely while the clamping assembly is open and is clamped thereto when the clamping assembly is closed. The clamping assembly (2) comprises first and second parts (5, 7) which are movable relative to each other in the traction direction (T) of the draw wire (4), with said first part (5) being a "fixed" part which is fixed to the charge by threshold releasable fixing means (6a, 6b) sensitive to traction in said traction direction (T), and said second part (7) being slidably mounted to move relative to the charge in said traction direction (T), and being connected to the draw wire (4).

Abstract: An apparatus and method for establishing the alignment of heat seeking missiles with the longitudinal axis of a launch pod within which the missiles are contained is disclosed. A housing containing a heat source and collimating optics provides a simulated distant infrared target for the missiles. A tapered probe rigidly attachable to the housing fits securely into a central alignment socket in the launcher pod. The probe is accurately offset from the center line of the alignment socket by the housing to establish the optical axis of the simulated target parallel to the axis of the launcher pod, and in front of the stored missiles. The position of the missile within the launch pod is adjustable to maximize the target signal strength received by the missile from the simulated target to achieve missile alignment with the axis of the launcher pod.

Abstract: An improvement is made in an externally driven gun having an ammunition feeder capable of providing at least two types of ammunition to the gun by incorporating a gear transmission into the driving mechanism coupled to the ammunition feeder to appropriately control an in-feed sprocket within the ammunition feeder so that the ammunition type can be changed prior to commitment of the previously selected type of ammunition to the firing mechanism of the gun. The gear transmission which is coupled to the in-feed sprocket provides acceleration to the sprocket at the last possible moment prior to handing-off the round to the firing mechanism. In one embodiment the gear transmission includes a cam follower rotatably coupled about an offset axis to the input shaft and coupled to the output shaft through a radial slot. The cam follower is rotated by means of a stationary cam race as the follower itself is rotated as a whole by the input shaft.

Abstract: In weapons in the nature of a Gatling gun the danger exists with an ignition delay or hangfire that the cartridge still is ignited after the positively reciprocated breechblock has been unlocked. However, cartridge ignition is undesired after unlocking of the breechblock. Therefore, an apparatus is present with the invention preventing unlocking of the breechblock in case of an ignition delay. Such safety apparatus may respond to (a) the gas pressure, (b) the weapon recoil, (c) the forward advance of the weapon or (d) to an expansion or bulge formed in a cartridge case, and acts to separate a breechblock head from a breechblock carrier, the breechblock head remaining in its locked position.The apparatus comprises either an inertia mass displaced relative to the breechblock due to the recoil action or a cam plate mounted at the weapon cradle and responding to the forward advance of the weapon, or a feeler pin responsive to an expansion or bulge formed in the cartridge case.

Abstract: An externally powered automatic cannon comprises a receiver, a barrel conted to the receiver and having a bore with a rear end opening toward the receiver, a chamber member having a chamber for a propellant case movable in the chamber and a cam drum rotatable on the receiver and engaged with the chamber member for moving the chamber member from an operating position with the chamber aligned with the rear end of the bore, to a loading position with the chamber misaligned with the rear end of the bore and spaced therefrom. A projectile feeder with ram, rams a projectile into the now exposed rear end of the bore. At the same time a propellant case feeder with ram, rams a propellant casing to the opened chamber. Continued rotation of the cam drum returns the chamber member into its operating position at which time the propellant is ignited to propel the projectile down the barrel bore. The cycle is repeated with each rotation of the cam drum for rapid automatic firing of the cannon.

Abstract: An apparatus for killing fire ants by means of a concussion explosion within the mound of the ants is disclosed. The apparatus includes an elongated shell containing an explosive powder removably mounted at one end of an elongated barrel by means of a holding mechanism. A firing mechanism, is mounted at the opposite end of the barrel for remotely exploding the shell. The outermost part of the shell is tapered to facilitate movement of the shell and the barrel through a wall of the ant mound prior to exploding the shell.

Abstract: A regenerative liquid propellant gun structure in which the differential area piston is annular, having a peripheral cylindrical skirt extending away from the combustion chamber to define a propellant reservoir, and has an aperture permitting overrunning of a fixed bolt. The fixed bolt is shaped to define with the edge of the aperture a variable annual orifice for propellant injection as the piston moves. There is a second free piston overrunning the bolt and mating with the inside of the differential area piston to complete and provide for emptying of the reservoir. The structure also contains a spring to allow components to move responsive to increased combustion chamber pressure to provide for an initial movement of differential area piston relative to the bolt to start propellant injection and a fluid pressure means for movement of pistons after firings to facilitate reloading.

Abstract: A hand held, shoulder mounted gun with time delay circuitry means to safely ignite a powdered pyrotechnic material.

Abstract: A method of clearing a target range or other area of buried unexploded ornce (UXO) by advancing natural galvanic electrochemical corrosion whereby ferrous parts of the UXO is simply rusted away at an accelerated rate and rendered harmless within 5 to 10 years in a safe manner and at substantially reduced cost. The electrolytic condition of the soil containing the UXO is preferably enriched. The soil may be saturated with a liberal amount of salt water or other electrolytic chemicals for establishing a corrosive bed several feet below the surface and a dc voltage applied across the soil to enhance stray current corrosion. The galvanic action of the soil electrolyte may be further enhance by elevating its temperature such as by selective covering with black plastic sheets.

Abstract: A single barrel externally powered gun includes a feed mechanism, a bolt assembly, a bolt control assembly and a power transmission system. The bolt control assembly is in the form of a chain drive unit driven continuously along a predetermined path of travel which defines the timing and sequence of loading, ramming, firing and ejecting. The chain drive assembly controls the reciprocating motion of the bolt assembly relative to a fixed non-rotating and non-reciprocating barrel, the bolt being stationary in the firing and loading sequences. The feed mechanism which continuously advances rounds is integrated to the intermittent motion of the bolt by a Geneva wheel mechanism, as the bolt assembly reaches the proper position in its rearward movement. Bolt locking, firing and unlocking are all controlled, and carried on while the chain drive assembly is continuously moving.

Abstract: A single barrel externally powered gun includes a feed mechanism, a bolt assembly, a bolt control assembly and a power transmission system. The bolt control assembly is in the form of a chain drive unit driven continuously along a predetermined path of travel which defines the timing and sequence of loading, ramming, firing and ejecting. The chain drive assembly controls the reciprocating motion of the bolt assembly relative to a fixed non-rotating and non-reciprocating barrel, the bolt being stationary in the firing and loading sequences. The feed mechanism which continuously advances rounds is integrated to the intermittent motion of the bolt by a Geneva wheel mechanism, as the bolt assembly reaches the proper position in its rearward movement. Bolt locking, firing and unlocking are all controlled, and carried on while the chain drive assembly is continuously moving.

Abstract: A clutch assembly includes axially aligned shafts, one driving and one driven, the driving shaft including a plurality of slots and the other a plurality of apertures aligned with the slots. Elongated roller bearings are positioned in the slots and apertures to lock the shafts together, a resilient member being used to urge the bearings radially inwardly. In the event that one of the shafts slows substantially relative to the other, the bearings move radially outwardly to declutch the shafts.

Abstract: A hangfire protection system for an externally powered gun includes a recoil sensing mechanism cooperating with a sear latching mechanism such that in the event of a hangfire, a sear engages a safety link on the chain drive assembly to keep the bolt locked. If the round fires, gun function continues; if the round does not fire there is a delay of a sufficient time to assure that the round is a dud, and it is ejected. The details of the mechanical hangfire protection system are described.

Abstract: A mechanism is provided to detect the occurrence of a misfire in an automatic gun and for thereupon halting, prior to the unlocking of the gun, the further operation of the gun; which is particularly adapted to liquid propellant guns having a rotating drum.

Abstract: A helical lock for an automatic gun operated by a rotating drum wherein a cking ring and mating end of the chamber have helical surfaces, whereby upon rotating the locking ring to locked position, the chamber is snugly urged into the barrel in its battery position and thus prevent gas leakage therebetween.

Abstract: This disclosure relates to an automatic firearms having a rotatable drum with helical grooves therein so arranged as to cause a follower guided by said grooves to reciprocate at a speed proportional to the rotational speed of the drum. The reciprocation of the follower causes the breech mechanism to reciprocate between loading and firing positions. The drum is driven by means independent of the propulsion energy of the projectiles fired, and therefore, may be operated at varying speeds by means such as an electric motor or even by hand.

Abstract: A liquid propellant modular gun has a slim profile and is constructed for wide latitude in gun cluster configuration.The modular gun has a stationary barrel and is externally driven and cam operated by a drive cam and a control cam.The drive cam has one internal spiral cam track for driving the bolt forward to a projectile firing position and another internal spiral cam track for driving the bolt rearward to a projectile loading position.The control cam is mounted for rotation at the forward end of the drive cam and controls the injection of liquid propellant into the combustion chamber and an electrical igniter.A water injection mechanism is also associated with the control cam for injecting a small amount of water into the combustion chamber after the firing of each round to cool the combustion chamber structure by internal water cooling. The water injection mechanism is also effective to purge propellant from the combustion chamber in the event of a misfire.

Abstract: A liquid propellant modular gun has a slim profile and is constructed for wide latitude in gun cluster configuration.The modular gun has a stationary barrel and is externally driven and cam operated by a drive cam and a control cam.The drive cam has one internal spiral cam track for driving the bolt forward to a projectile firing position and another internal spiral cam track for driving the bolt rearward to a projectile loading position.The control cam is mounted for rotation at the forward end of the drive cam and controls the injection of liquid propellant into the combustion chamber and an electrical igniter.A water injection mechanism is also associated with the control cam for injecting a small amount of water into the combustion chamber after the firing of each round to cool the combustion chamber structure by internal water cooling. The water injection mechanism is also effective to purge propellant from the combustion chamber in the event of a misfire.

Abstract: A liquid propellant modular gun has a main cam which is driven at a multiple of the gun firing rate and which has internal cam surfaces operatively associated with the bolt while the bolt is driven forward to load and fire and backward to accept another projectile.The gun incorporates a control cam driven at the gun firing rate and effective to unlock the bolt after firing of a projectile so that the bolt can be returned to its rearward position under the control of the main cam.The main cam acts to time all the remaining mechanisms of the gun to the bolt motion.The accelerating force for the bolt is provided by hydraulic pressure applied directly to the bolt area.Energy stored in the bolt from the force of the accelerating hydraulic pressure is converted into rotary energy and is stored in the main cam and other rotating devices geared to the main cam.

Abstract: An improved bi-propellant injection system for a liquid propellant gun inding a valve which is positively opened at the start of the injection of the fuel and oxidizer into the gun chamber and held at a predetermined displacement to provide a constant size propellant orifice throughout the fuel and oxidizer injection cycle.