Abstract:
A recoil control mechanism for a weapon which fires a projectile which is characterized by the generation of a forward counterforce to the rearward recoil simultaneously with absorption of rearward recoil force upon initiation of propoulsion of the projectile. The forward counterforce is generated by propelling a first mass forwardly upon firing the projectile and substantially simultaneously propelling a second mass rewardly for absorbing some of the recoil force. In one mechanism ( 10 ), the first mass may be the weapon&#39;s barrel ( 12 ) and the second mass its breach block ( 14 ). Expaning gases ( 36 ) from detonation of propellant in cartridge ( 24 ) enter a reaction volume ( 28 ) between the barrel ( 12 ) and breech block ( 14 ). These gases drive barrel ( 12 ) forwardly against force transmission spring ( 16 ) to impose a forward counterforce on the weapon&#39;s frame ( 18 ). Substantially simultaneously recoil from detonation of cartridge ( 22 ) together with the gasses ( 36 ) in reaction volume ( 28 ) drive breech block ( 14 ) rearwardly against force absorbing spring ( 20 ).

Description:
This application is a Continuation of PCT International Application No. PCT/AU01/00220, filed on Mar. 2, 2001. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a weapon and in particular to a recoil control mechanism for a weapon. The invention will be described generally in relation to a firearm, however it is to be understood that the invention is applicable to other forms of weapons for firing a projectile. Thus the weapon may, for example, be a large calibre weapon which is supported on a mounting such as a stand or platform instead of a hand held portable weapon such as a firearm. 
     In this specification the term “projectile” is to be understood as encompassing one piece generally solid projectiles such as bullets, pellets, darts, flechettes, artillery warheads, projectiles as in for example WO 97/04281, mortar shells (eg. 120 mm) or rocket boosted artillary shells, plus multiple piece charges which are fired as one, such as the shot in a shotgun cartridge or a plurality of bullets fired as one. 
     BACKGROUND 
     A problem with all weapons which fire a projectile, particularly those that rely upon detonation of an explosive propellant, is recoil. That is, firing the weapon (for example by detonation of a charge of explosive propellant within the weapon) produces a forward propelling thrust on the projectile and an equal and opposite rearward force, or recoil. Recoil limits the accuracy and portability of weapons. First it produces a force which has the effect of rotating the weapon about the centre of gravity of the weapon and its support (which for a firearm would be the shooter), resulting in vertical climb and lateral drift of the muzzle end of the barrel for succeeding firings. Recoil forces also cause torque, which has the effect of ‘twisting’ the weapon. The muzzle is thrown off the target in an irregular half circular motion around the longitudinal axis of the barrel. Similar to the effect of muzzle climb, the time of reacquisition of the target is therefore increased for subsequent rounds and accuracy is therefore significantly affected. 
     During automatic firing recoil can significantly affect the accuracy of the succeeding rounds. Second, the force of recoil must be absorbed by the weapon, or the shooter if the weapon is a firearm, or transmitted to a support mounting and thus to ground for heavier weapons such as artillery pieces. Thus it may cause discomfort and fatigue or even injury to a shooter, or require heavier supporting structures, or complex “soft” mounting carriages for mobile artillery weapons. Large masses are sometimes used in firearms to absorb the recoil velocity, however this compromises portability. 
     Clearly, if the recoil of a weapon could be substantially reduced if not eliminated within the weapon itself, it would reduce the above problems. 
     There are many known recoil reducing mechanisms, including arrangements which are initiated by the rapidly expanding gases produced by the detonation and burning of an explosive propellant. Generally, however, the known arrangements effectively only reduce the recoil without cancelling or at least substantially eliminating it. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an improved recoil control mechanism. 
     The invention is characterised by the generation of a forward counterforce to the rearward recoil simultaneously with absorption of rearward recoil force momentarily after propulsion of the projectile is initiated. 
     Accordingly, in a first aspect the invention provides a recoil control mechanism for a weapon for firing a projectile in a forward direction which includes a first mass and a second mass which are driven in substantially opposite directions upon firing, wherein the first mass is driven in the forward direction to counter a rearward recoil of the weapon and the second mass is driven in the rearward direction for absorbing some of the recoil force. 
     The first mass and the second mass are solid inertial weights. 
     Preferably the mechanism includes a frame, the first mass and the second mass being associated with the frame for the frame to guide their respective forwards and rearwards movement, and including a force absorbing means which is operative between the second mass and the frame and a force transferring means which is operative between the first mass and the frame. 
     In a second aspect the invention provides a method of countering recoil of a weapon caused by the firing of a projectile, the method including providing a first mass to be driven forwardly in the same direction as the projectile to counter a rearwards recoil force and providing a second mass to be driven rearwardly against a force absorbing means for substantially simultaneously absorbing some of the rearwards recoil force. 
     The generation of a forward counterforce simultaneously with absorption of the residual recoil force over the time period of the recoil, allows the achievement of a resultant force-time characteristic which may be reasonably predetermined. For example, for a projectile which is fired by detonation of an explosive propellant, the recoil force of a weapon is reasonably calculable from, knowledge of the amount and type of propellant and the masses etc. that are involved, or it may be empirically determined experimentally, and from this appropriate parameters for the counterforce and recoil absorption sub mechanisms can be calculated (and possibly experimentally adjusted) to give a predetermined resultant force-time characteristic. Thus the invention gives an improved recoil control mechanism. It is envisaged that in some embodiments of the invention, the recoil of the weapon may be at least substantially eliminated if not fully cancelled (that is, the resultant force is substantially zero over the recoil time period). It is also considered that a resultant forward force could be generated. 
     Preferably the first mass is a barrel and the second mass is a breech block of the weapon and a means is provided associated with the barrel and a frame of the weapon for transferring a forwards force to the frame from the forward motion of the barrel. This means may include a compression spring or pneumatic or hydraulic piston and cylinder arrangement or electromagnetic means which is operative to return the barrel to its firing position. 
     The barrel and the breech block are also preferably biased towards each other relative to the frame of the weapon. This bias may be provided by a tension spring which is connected between the barrel and the breech block. Thus, as force from the forward momentum of the barrel is being transferred to the frame, the rearwards recoil force imparted to the breech block is being absorbed by the tension spring. Thus the tension spring provides a force absorbing means against which the breech block is driven. The tension spring may also be operative to restrain the breech block in its firing position momentarily upon detonation of the propellant to provide an adequate reaction surface for initiating the forward movement of the projectile and then to return it to its firing position after its rearward movement. 
     Alternatively the bias of the breech block and the barrel towards each other may be provided by means acting independently between the barrel and the frame and the breech block and the frame. Such means acting between the barrel and the frame may constitute the above described means for transferring a forwards force to the frame from the forward motion of the barrel. The independent means may each comprise a helical spring. 
     Although the preferred embodiment combines simultaneous “blow forward” of the barrel and “blow back” of the breech block to control recoil, as described above, it is to be understood that the invention may be realised in alternative embodiments. For example, it is envisaged that the first mass and the second mass may be additional components and that a gas for driving them apart may be tapped from the barrel or firing chamber. The recoil control mechanism may also be provided as an attachment per se for a weapon. Various of the foregoing or following features for biasing the breech block and barrel and providing gas reaction surfaces may be adapted to the masses of such alternative embodiments. 
     In the preferred arrangement wherein the first mass is a barrel and the second mass is a breech block of the weapon, a chamber for receiving a cartridge containing the projectile (such as a bullet) and explosive propellant is preferably provided at a loading end of the barrel. The chamber is associated with the barrel and the breech block to provide an interposed gas contact region therebetween for receiving expanding gases from the chamber upon firing of the projectile from the cartridge. Thus, upon firing of the cartridge, expanding gases from the propellant force the projectile from the cartridge and propel it through the barrel, and momentarily after initiation of the projectile&#39;s movement, the expanding gases following the projectile which emerge from the cartridge into the chamber expand into the interposed gas contact region to blow the barrel forward and simultaneously blow the breech block backwards to thereby reduce if not eliminate the recoil of the weapon. The chamber may be provided by the barrel, by the breech block, or the barrel and the breech block in combination, or by a separate chamber member. Preferably the component or components providing the chamber are in a structural relationship such that the interposed gas contact region is defined in part by at least two facing reaction surfaces, with each reaction surface being directly or indirectly associated with one of the barrel or the breech block. Preferably the reaction surfaces are substantially normally orientated relative to the forward and rearward directions to maximise the forces applied thereto in the forward and rearward directions by the gas pressure. The aforesaid structural relationship may be realised by a telescopic arrangement of one component relative to another, as will be described in more detail below. 
     It is to be understood that the weapon will include a firing mechanism for initiating detonation of the explosive propellant and in the preferred embodiment this may include a firing pin associated with the breech block which is operable via a trigger mechanism carried by the frame, as is known. The weapon may also provide for semi automatic or fully automatic operation utilising the energy stored during the blow back of the breech block, as is also known, in which case a magazine will need to be provided. A suitable firing mechanism and a mechanism for providing semi or fully automatic operation including a magazine for the cartridges will not be described in further detail herein as there are many such known mechanisms from which a person skilled in the art may choose to provide suitable such mechanisms for the weapon. 
     A weapon incorporating the invention, in its preferred form involving blow forward of the barrel, may include additional features associated with the barrel for increasing the forwards momentum thereof. Such additional features include, for example, the provision of a conical bore for the barrel and/or muzzle breaks for redirecting the gas from the barrel, as are known. The weapon in its preferred form may be a firearm such as a rifle, shotgun, pistol or revolver. 
     For a better understanding of the invention, the principle thereof for various embodiments, as well as a specific embodiment, which are given by way of non limiting example only, will now be described with reference to the accompanying drawings (which are not to scale). 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIGS. 1 to  4  schematically illustrate the operating principle of the invention. 
     FIG. 5 schematically illustrates use of a barrel, chamber unit and breech block for the invention. 
     FIGS. 6A-D and  7 A-F illustrate further embodiments in principle. 
     FIG. 8 is a partially sectioned side view of an embodiment of the invention in the form of an automatic pistol, and 
     FIG. 9 is a partially sectioned view of a portion of the pistol of FIG. 8 showing the slide (that is breech block) in its rearmost position. 
    
    
     DETAILED DESCRIPTION 
     A recoil control mechanism  10  of a weapon as schematically shown in FIGS. 1 to  4  includes a first mass which is a barrel  12  of the weapon and a second mass which is a breech block  14  of the weapon. The barrel  12  is movable in a forward direction against a biasing means  16  relative to a frame  18  of the weapon and the breech block  14  is movable rearward against a biasing means  20  relative to the frame  18 . The biasing means  16  and  20  may be helical compression springs. The barrel defines a chamber  22  at its loading end, for receiving a cartridge  24  with a bullet  25 , and is telescopically received within a recess  26  in the breech block  14 . 
     The recess  26  of the breech block and the barrel  12  are shaped such that when in the ready to fire position (FIG. 1) they define an interposed gas contact region, namely an annular volume  28 . Ports  29  provide for gas flow from chamber  22  into volume  28 . The interposed gas contact region  28  is defined in part by a reaction surface  30  on the barrel  12  and a facing reaction surface  32  on the breech block  14 . The surfaces  30  and  32  lie substantially normally to the forward and rearward directions. A firing pin  34  is associated with the breech block  14 . 
     On firing, the rapidly expanding gases  36  from the explosive propellant in cartridge  24  propel bullet  25  into the bore of barrel  12  and also flow through ports  29  into the interposed gas contact region  28  (FIG.  2 ). The very high pressure gases entering region  28  act on reaction surfaces  30  and  32  and thus simultaneously force or “blow” the barrel  12  forwardly (arrow A, FIG. 3) and the breech block  14  rearwardly (arrow B, FIG.  3 ). Initiation of the blowing forward of the barrel  12  and blowing back of the breech block  14  occurs momentarily after firing because of the proximity of ports  29  and chamber  22 . The force of the rearward or recoil movement of the breech block  14  is absorbed by biasing means  20  which has a suitable characteristic relative to that of biasing means  16  to ensure it stores a significant portion of the force instead of immediately transferring it to frame  18 . Simultaneously, the force from the forward movement of barrel  12  is transferred to frame  18  via biasing means  16 , which has a relatively stiffer characteristic compared to that of biasing means  20  to ensure that the counter recoil force is quickly transferred to the frame  18 . Thus the rearward recoil which occurs upon detonation of the explosive in cartridge  24  and expansion of gases  36  therefrom to propel bullet  25  through barrel  12  is simultaneously both absorbed in biasing means  20  and countered by an oppositely directed force applied to frame  18  from barrel  12 . The resultant of this may be to totally or at least substantially eliminate recoil of the weapon. At the limit of the forward movement of barrel  12  and rearward movement of breech block  14  (FIG. 4) the cartridge  24  is ejected by ejector  35  and the biasing means  16  and  20  are operative to restore the parts to their ready to fire positions. 
     FIG. 5 schematically shows a modification wherein a chamber unit  40  is provided interposed between a breech block  14  and barrel  12  (the components of FIG. 5 which are equivalent to those in FIGS. 1 to  4  have been given the same reference numeral, but note that some features have been omitted from FIG. 5 for clarity). A forward cylindrical portion  42  of chamber unit  40  telescopically engages in a wider cylindrical recess  44  in barrel  12  to provide an interposed gas contact region  28  defined in part by facing reaction surfaces  30  and  32  of, respectively, the barrel  12  and the chamber unit  40 . With this construction, the ports  29  are eliminated, however it functions the same as the construction of FIGS. 1 to  4 . 
     The reaction surfaces of the interposed gas contact region may have any desired shape. Thus instead of being flat, as shown in FIGS. 1 to  5 , they may have curved portions, be fluted, include depressions or be otherwise modified to increase the surface area upon which the rapidly expanding pressurised gases  36  act. 
     After the pressure of the expanding gases has reduced, the breech block  14  and barrel  12  are returned to the positions shown in FIG. 1 by the energy stored in biasing means  20  and  16 , respectively. A mechanism for automatic ejection of the cartridge case  24  is indicated at  35  (FIG.  4 ). A mechanism for automatic loading of another cartridge in chamber  22  ready for firing is not shown in FIGS. 1 to  5 , but as is known may be operated by the backward and then forward motion of the breech block  14 , or alternatively the forward and then rearward motion of the barrel  12 , or a combination of both. 
     FIGS. 6A to D illustrate in principle a weapon where recoil is controlled by simultaneous “blow forward” of a barrel and “blowback” of a breech block without use of an interposed gas contact region. Thus the figures show a weapon  50  which comprises a frame  52  on which is reciprocally mounted a barrel  54  biased rearwardly by a compression spring  56 . The frame  52  also carries a breech block  58  which is biased forwardly by compression spring  60 . 
     On detonation of a cartridge  62 , the bullet  64  is propelled forwardly and its motion through the barrel  54  drives the barrel forwardly and this motion continues after the bullet  64  exits the barrel  54  (FIGS. 6B, C and D). Also upon firing, a rearwards force from the cartridge  62  is impacted on the breech block  58  and this drives the breech block rearwardly against the bias of spring  60 . Spring  56  is relatively weak such that a forwards force is generated by the moving mass of barrel  54  to counter the rearwards recoil. Some of this force is transferred to frame  52  via spring  56  such that, combined, a substantial forwards counter to the rearwards recoil is generated. Simultaneously the recoil force imposed on breech block  58  is absorbed by spring  60 . It is considered that the masses of barrel  54  and breech block  58  and the spring characteristics of springs  56  and  60  could be arranged such that recoil is effectively eliminated. 
     FIGS. 7A to F illustrate a weapon  80  having a frame  82  on which is mounted a barrel  84  and breech block  86 . A moveable mass  88  surrounds the barrel  84 . The barrel  84  is biased to its rest position relative to frame  82  by spring  90 , and mass  88  is biased against an abutment  92  on barrel  84  relative to frame  82  by a double spring arrangement  94 . Breech block  86  is biased forwardly relative to frame  82  by a spring  96 . An interposed gas contact region is defined by facing surfaces of the abutment  92  on barrel  84  and an end face of the mass  88  and is in gas communication with a chamber part of the barrel  84  via passages  98 . 
     The sequence of events for recoil control in the weapon  80  upon firing of a cartridge  100  will be evident from FIGS. 7A to F. Thus, on detonation, the barrel is initially driven forwardly against the bias of spring  90  by bullet  102  and virtually instantaneously gas forces into the gas contact region to drive mass  88  forwardly against double spring  94 , the initial portion of which is readily compressible (FIGS.  7 A and B). Spring  96  drives breech block  86  forwardly with the barrel  84 . Whilst mass  88  continues forwardly, barrel  84  is then driven rearwardly by spring  90  and gas pressure on abutment  92  to drive the breech block  86  rearwardly against spring  96  (FIGS. 7C, D and E). This extracts the cartridge case  100  from the chamber end of barrel  84 . Mass  88  continues forwardly, but is now moving against a stronger bias provided by the second portion of the double spring arrangement  94  until it reaches its forward most position (FIG.  7 F), at which point the breech block  86  also reaches substantially its rear most position. The mass  88  and breech block  86  are then reset to their initial positions by the energy which is stored in springs  94  and  96 , respectively. 
     The initial forward movement of barrel  84 , breech block  86  and mass  88  combined with the subsequent rearward movement of barrel  84  and breech block  86  against spring  96  simultaneously with continued forwards movement of mass  88  against double spring  94  allows for the recoil in the weapon  80  to be controlled. 
     An example weapon, namely a pistol  100  incorporating an embodiment of the invention, comprises a frame  102  (FIGS. 8 and 9) having a handle  104  within which a magazine  106  is received. Mounted on the frame  102  is a barrel  108  and a breech block in the form of a slide  110 . A breech face  112  of the slide (best seen in FIG. 9) closes a chamber  114  provided by a chamber unit  116 , and a forward portion  118  of the slide surrounds the barrel  108 . Forward portion  118  of the slide  110  includes a bushing  120  for supporting the forward end of barrel  108  for relative movement therebetween. 
     The slide  110  is rearwardly movable relative to frame  102  against the bias provided by a helical compression spring  122  which acts between a boss  124  which is pinned to the frame  102  by a pin  126  and a spring holding bracket arrangement  128  provided on the forward portion  118  of the slide beneath barrel  108 . A pin member  130  (which may be cylindrical) extends through bracket  124  for guiding and supporting the spring  122  as it compresses with rearwards movement of slide  110 . The frame  102  includes an extension  132  for covering the spring  122 . 
     The barrel  108  is forwardly movable relative to frame  102  against the bias provided by a helical compression spring  134  which acts between the boss  124  pinned to frame  102  and a depending lug  136  of the barrel  108 . The pin member  130  is associated with the lug  136  for supporting spring  134 . Pin member  130  can slide through boss  124 . A rib on the lowermost surface of lug  136  of barrel  108  slides within a groove in the frame  102  to guide the barrel. 
     Frame  102  carries a firing mechanism which includes a trigger  138  and hammer  140  adapted to be cocked by the slide  110  when it moves rearward from the position shown in full lines in FIG.  8 . Details of the firing mechanism are not shown but may be the same or similar to that in a Colt “Ace” pistol, upon which the present embodiment is modelled. When trigger  138  is pulled, the hammer  140  is released to strike the rear end of a firing pin  142  carried by the slide  110 . 
     The chamber unit  116  includes a cylindrical forward portion for telescopically engaging within a cylindrical recess in the rear end of barrel  108  to provide an interposed gas contact region  144 . The gas contact region is partly defined by facing reaction surfaces of the barrel and the chamber unit. The rear portion of chamber unit  116  includes a depending extension  146  (see FIG. 9) which includes a slot  148 . A pin  150 , which is fixed to the frame  102 , passes through the slot  148  whereby the slot and pin  150  in combination define the forward and rearward limits of movement of the chamber unit  116 . A V spring  152  is retained between the depending extension  146  of chamber unit  116  and a surface of frame  102  to bias the chamber unit  116  towards its forward most position. Extension  146  includes a rearward projection which has an inclined upper surface  154  (best shown in FIG. 9) for providing a ramp for guiding cartridges into the chamber  114 . 
     The slide  110  includes an extractor adapted for engaging and withdrawing cartridges from chamber  114  when the slide  110  moves rearward. When the cartridge shell is drawn back by the extractor it is engaged by an ejector and thrown out through ejection opening  156  in the slide  110  (see FIG.  9 ). 
     The magazine  106  holds cartridges  158 , the uppermost of which rests against a depending central rib  160  on the slide  110 . The magazine is provided with a known spring follower to press the cartridges upward successively as each topmost cartridge is withdrawn and fired by the pistol  100 . 
     FIG. 8 shows the pistol  100  loaded and cocked. Upon firing, the cartridge and chamber unit  116  recoil rearwardly (against the bias of V spring  152 ) and at virtually the same instant some of the high pressure expanding gases enter the gas contact region  144  and impinge on the reaction surfaces to blow the chamber unit  116  and barrel  108  apart. This drives the chamber unit  116  and slide  108  rearwardly against the bias of the spring  122 . The chamber unit  116  stops when the forward end of slot  148  contacts pin  150 , but slide  110  continues rearwardly for the recoil force to be further absorbed by spring  122 . Simultaneously force from the forward movement of the barrel  108  is transferred to frame  102  via spring  134  acting between lug  136  and boss  124 . This force counteracts the recoil, including that caused by extension  146  of chamber unit  116  striking pin  150  of frame  102 . The combined blowing back of the slide  110  and blowing forward of barrel  108  together with the action of springs  122  and  134  relative to frame  102  allows for the recoil of the pistol  100  to be substantially eliminated. 
     The slide  110  moves rearward to the position shown in FIG.  9  and thus recocks the firing mechanism. It is immediately returned forwardly by the energy stored in spring  122 , during which movement its central rib  160  engages the top most cartridge  158  in magazine  106  and pushes it forwards into chamber  114  of chamber unit  116 , by which time the chamber unit  116  has been reset by V spring  152 . The cartridge  158  is guided into chamber  114  by the inclined ramp surface  154  of chamber unit  116 . The slide  110  holds the chamber unit  116  forward in the position shown in FIG.  8 . At the same time the barrel  108  is returned rearwardly to its normal position shown in FIG. 8 by the energy stored in spring  134 . Recocking and reloading have thus been effected and the pistol  100  is ready to be fired again. 
     Although only a single detailed embodiment (FIGS. 8 and 9) has been described, the principle of the invention is not complex and is adaptable to other types of weapons without undue experimentation. Thus the invention is to be understood as applicable to weapons of much larger calibre, including mounted mobile or stationary artillery weapons. It is also considered that the invention is applicable to the types of weapons as disclosed in WO 94/20809 and WO 98/17962. 
     It is also to be understood that the invention is not restricted to applications where a projectile is fired via detonation of an explosive propellant, whether that propellant be encased, as in for example a cartridge, or otherwise presented for firing a projectile, as in for example caseless ammunition, or whether it be a solid, gaseous or liquid propellant. Thus, the invention is considered to be applicable to all types of weapons which fire a projectile and in which recoil occurs, notwithstanding the means or manner by which the high pressure is developed that is necessary to propel the projectile forwardly. It is considered that such means or manner may include for example electromagnetic (as in “rail guns”) or electrothermal systems, air propulsion systems of various types and others. 
     Finally, it is to be understood that various alterations, modifications and/or additions may be made to the present invention without departing from the ambit thereof as defined by the scope of the following claims.