Patent Publication Number: US-7895786-B2

Title: Adaptable firing pin assembly for a bolt action firearm

Description:
FIELD OF THE INVENTION 
     The present invention relates to firearms such as rim fire and centre fire rifles. It is particularly relevant to bolt action rifles having a receiver for receipt of a bolt assembly. 
     BACKGROUND OF THE INVENTION 
     A typical bolt action firearm consists of a receiver mounted in a stock of the firearm and bolt slidably received within an elongate chamber of the receiver. 
     By using a bolt handle which is typically provided on a collar piece, the bolt is able to slide between a receiver open position where a cartridge may be inserted into the receiver and a closed position where the bolt is locked in position, thereby restraining the cartridge into a firing chamber. 
     Typically, cartridges may be divided into two categories: centre fire, or rim fire. Centre fire cartridges have the ignition means located concentric to the bore axis and at the rear end of the cartridge. Rim fire cartridges contain the ignition means within the outer rear rim of the cartridge. 
     Typically the system for firing a centre fire cartridge in a bolt action firearm consists of a firing pin which is locatable in a central passage within a bolt which is able to rotate around the same axis as the bore of the barrel. Locking this bolt into the closed position is typically achieved by having protruding lugs at some distance along the rotatable bolt body engaging matching recesses within the receiver, or alternatively, matching recesses within the barrel. 
     The firing pin is typically assembled within the bolt body with a spring, which is typically mounted around the external surface of the firing pin. This main spring is typically restrained between a flanged face of the firing pin and the front face of the shroud. 
     By operating a firing mechanism the spring is able to force the firing pin to impact on the ignition means of the cartridge within the firing chamber. 
     Typically, the firing system for firing a rim fire cartridge in a bolt-action firearm consists of a bolt body that for part of its length is semi-circular in cross section. This bolt body typically does not rotate within the receiver. A rotating collar attached to this bolt body typically has mounted on it the means for locking the bolt assembly into the receiver. Typically, a firing pin is housed within the non-rotating bolt body, with the point/axis of impact directed at the rim of the cartridge within the firing chamber. Typically, this firing pin is acted upon by a spring also housed within the bolt body. By operating a firing mechanism the spring is able to force the firing pin to impact on the ignition means of the cartridge within the firing chamber. 
     By operating a firing mechanism the spring is able to force the firing pin to impact on the ignition mass of the cartridge within the firing chamber. 
     Typically centre fire and rim fire firearms have different designs and therefore components, which are differently designed. The design of a rim fire bolt action firearm is typically more complicated than that of the centre fire bolt action firearm because of the necessity of having offset centre striking of the cartridge by the firing pin. 
     Because rim fire and centre fire firearms require different components there is no easy way of modifying one type of firearm to allow it to fire cartridges of the other type. In other types of rifle and handgun actions, such as lever, pump, self-loading and revolving, the difference between rim and centre fire actions is typically little more than the location of the firing pin/impact member. 
     Preferably the present invention is aimed at allowing an assembly to be made for either rim or centre fire cartridges, the only potential difference between an example of each being the position of the impact member or firing pin relative to the bore axis of the firearm. 
     The present invention is aimed at providing a different assembly of components which can be used in a rim fire or centre fire firearm without major differences in the design of components to be used for either type. 
     Thus it is desired that an assembly in accordance with the present invention can be used in combination with existing firearm components with minor modifications if necessary for firing either rim fire or centre fire cartridges. 
     Typically the firing system for firing a cartridge consists of a striker with a firing pin which is locatable in a central passage through the bolt. The striker is typically provided with a spring which is either mounted around the external surface of the striker or is located directly behind the striker mounted on a spring support. 
     By operating a firing mechanism the striker spring is able to force the firing pin of the striker to impact on the cartridge within the firing chamber. Many firearms and in particular rifles are typically divided into rim fire and centre fire actions. 
     In a rim fire firearm, rim fire cartridges are used as a cheap way of providing powder, projectile and ignition source in one package. The rim of the cartridge is formed by folding the base of the cartridge to form a rim which contains a priming compound. The rim is struck by a firing pin which is off centre from the centre of the bolt. In contrast centre fire firearms have a centrally located firing pin which is designed to strike the centre of the rear of a cartridge. Typically the centre fire firearm is a more accurate firearm but the cartridges are more expensive. Hence both types of firearms are in common use. 
     Typically centre fire and rim fire firearms have different designs and therefore components which are differently designed. The design of a rim fire firearm is typically more complicated than that of the centre fire firearm because of the offset centre striking of the cartridge by the striker pin. 
     Because rim fire and centre fire firearms require different components there is no easy way of modifying one type of firearm to allow it to fire cartridges of the other type. 
     The present invention is aimed at providing a different assembly of components which can be used in a rim fire or centre fire firearm without major differences in the design of components to be used for either type. Thus it is desired that an assembly in accordance with the present invention can be used in combination with existing firearm components with minor modifications if necessary for firing either rim fire or centre fire cartridges. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention there is provided an assembly for a bolt action firearm comprising an impact member for impacting on a firing pin, a spring means and a housing for housing the impact member and spring means, wherein the impact member is configured to be located in the housing with the spring means behind the proximal end of a bolt having a firing pin and is able to be controlled by a firing mechanism to strike the firing pin proximal end when in a firing mode by release of energy stored by the spring means. 
     According to one embodiment of the present invention, the impact member is hinged within the housing and configured to use energy stored within the spring means to rotate the impact member into contact with the proximal end of the firing pin. 
     According to another aspect of the present invention there is provided a cocking piece having a distal end for striking a firing pin and having at least one lateral portion for retaining one end of a spring. 
     According to another aspect of the present invention there is provided an assembly for a bolt action firearm comprising an impact member for impacting a striker pin, a spring means and a bolt having a firing pin proximal end located in the proximal end of the bolt whereby the impact member is located behind the proximal end of the bolt and is able to be controlled to strike the firing pin proximal end when a firing mechanism is operated in a firing mode to release energy stored in the spring means. 
     The spring means preferably comprises at least one spring which may be a compression or extension spring. 
     Preferably the spring means is located behind the proximal end of the bolt. 
     Preferably the firing pin proximal end protrudes proud of the proximal end of the bolt when in the firing mode. 
     The impact member preferably comprises an elongate member with a collar at a distal end thereof. 
     The impact member is preferably configured to receive a spring of the spring means over an elongate portion. 
     Preferably the collar has a generally flat distal end surface which is configured to strike the head of the striker pin. 
     It is preferred that the striker pin fits within an elongate channel of the bolt. 
     The collar preferably comprises a cylindrical enlarged portion at the distal end of the impact member. 
     The collar and elongate portion are preferably concentrically arranged about a central longitudinal axis of the assembly. 
     According to another embodiment of the invention the impact member comprises a central bore which is adapted to receive at least part of the spring means. 
     Preferably a spring of the spring means fits into the bore of the impact member. 
     Preferably the outer peripheral surface of the impact member contacts the inner peripheral surface of the housing. 
     It is preferred that the housing includes a distal inner peripheral threaded portion which is adapted to receive a threaded portion of the bolt. 
     The assembly may include a housing for coaxially aligning the impact member and the bolt. 
     The firing pin may be centrally located in a bolt or offset from the centre of the bolt. 
     The bolt body may accommodate multiple firing pins. 
     The firing pin may incorporate a striker. 
     Preferably the housing includes a detachable shroud located over the proximal end of the bolt. 
     The bolt proximal end may comprise an enlarged portion having a greater diameter than the main body of the bolt. 
     Preferably the enlarged portion comprises a substantially cylindrical collar. 
     The shroud may have guidance portions for receiving pins on which the striker piece is able to slide. 
     The impact member may or may not protrude from the rear or distal end of the shroud. 
     Preferably the impact member includes a retainer means for retaining the spring means. 
     The retainer means may comprise lateral portions extending from a main body portion of the impact member. 
     The retainer means may comprise a flange of greater size than the main body of the impact member. 
     The retainer means may comprise rebated or counter bored recesses in a face of the impact member. 
     The main body may comprise a cylindrical rod. 
     The lateral portions may comprise a pair of left and right side lugs. 
     Preferably the left and right side lugs include holes adapted to align the impact member to slide on the pins. 
     According to one embodiment there is provided a single collar. 
     The spring means may comprise a central spring or a plurality of lateral springs. 
     It is preferred that two springs are located behind the lateral portions and rest against a rear wall of the housing. 
     The housing may include lateral channels for receipt of springs. 
     The housing may include a central channel for receipt of the impact member. 
     The lateral portions may be located at the distal end of the impact member. 
     The impact member preferably comprises a cocking piece. 
     The housing may comprise a seat for the impact member and spring means. 
     The housing may include a provision for a safety mechanism. 
     The housing may include a seating arrangement for a shroud. 
     Preferably the housing is formed from detachable upper and lower parts. 
     The impact member may have a sear or spigot for engagement by a clip when the bolt is pulled back. 
     According to an alternative embodiment the impact member comprises an annular hole in a distal end thereof for receiving one end of the spring means. 
     The bolt body may be formed from separate parts. 
     The housing may include a window for a cam surface. 
     The cam surface preferably co acts with the sear. 
     It is preferred that the firing pin is moveable with the bolt. 
     Preferably the firing pin returns to the firing mode by action the bolt body being closed upon a cartridge in the firing chamber. 
     Alternatively the firing pin returns to the firing mode proud of the proximal end of the bolt by action of a compression spring. 
     According to another embodiment of the invention the pin includes a detent which is able to be engaged by a cam surface of a sleeve member riding on the bolt. 
     According to one embodiment the bolt proximal end has a peripheral thread which is configured to screw into a distal end of the housing. 
     According to another embodiment the proximal end of the bolt includes a protrusion configured to act as a cam to force the impact member to compress a main spring of the spring means against a proximal inner wall of the housing. 
     According to another embodiment of the present invention the impact member comprises a lateral pin which is configured to contact a cam portion of the bolt. 
     According to one embodiment the cam portion is removably connectable to the bolt. 
     According to a further embodiment of the present invention the impact member comprises an elongate member with a centrally located collar portion. 
     It is preferred that the lateral pin is located on a distal side of the collar. 
     It is preferred that rotation of the cam surface allows the cam surface to act upon the pin to force the spring to be compressed between the collar and an inner surface of the housing. 
     According to one embodiment the proximal end of the bolt has one or more pins/protrusions for engaging with a cam surface on the distal end of the impact member to permit cocking of the impact member, while the bolt body is being moved out of the cocked position. The reverse configuration is also possible. 
     Preferably for this action of the cam surface to take place, the impact member must be prevented from rotating relative to the bolt body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A preferred embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which: 
         FIG. 1  shows a perspective view of a striker assembly according to a preferred embodiment of the present invention; 
         FIG. 2  shows a disassembled perspective view of the striker assembly shown in  FIG. 1 ; 
         FIG. 3  shows a perspective view of an assembled striker assembly with a top cover of the housing of the assembly removed; 
         FIG. 4  shows the assembly shown in  FIG. 1  in a first mode of operation with springs removed; 
         FIG. 5  shows the assembly shown in  FIG. 4  in the second mode of operation; 
         FIG. 6  is a cross-sectional side view of a bolt and firing pin in accordance with a preferred embodiment of the invention; 
         FIG. 7  shows a disassembled perspective view of a striker assembly according to another embodiment of the present invention; 
         FIG. 8  shows a cross-sectional perspective view of the assembly shown in  FIG. 7  with a bolt body; 
         FIG. 9  shows a close-up view of the assembly shown in  FIG. 8 ; 
         FIG. 10  shows a close-up view of the assembly shown in  FIG. 8 , with the striker in the fired or uncocked position; 
         FIG. 11  shows the assembly shown in  FIG. 8  assembled with a receiver assembly and sectioned to show that the striker is in a cocked or ready to fire state; 
         FIG. 12  shows the assembly shown in  FIG. 11  sectioned to show that striker is in a fired or uncocked state; 
         FIG. 13  shows a disassembled perspective view of a striker assembly according to a further embodiment of the present invention; 
         FIG. 14  shows a close-up view of the assembly shown in  FIG. 13 ; 
         FIG. 15  shows a disassembled view of a striker assembly according to an additional embodiment of the present invention; 
         FIG. 16  shows a perspective cross-sectional view of the assembly shown in  FIG. 15  when assembled with a bolt body; 
         FIG. 17  shows the assembly shown in  FIG. 16  with the striker in the firing or cocked position; 
         FIG. 18  shows the assembly shown in  FIG. 16  assembled with a receiver assembly and stock in the fired or uncocked position; and 
         FIG. 19  shows the assembly shown in  FIG. 16  assembled with a receiver assembly and stock when the bolt body has been rotated into the unlocked position. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     As shown in  FIG. 1  the striker assembly  11  is positioned behind the bolt  12 . The bolt  12  is modified as shown in  FIG. 2  and is provided with a small off centre axial bore (rim fire—version) sized to receive a long thin firing pin (shown more clearly in  FIG. 6 ). Referring to  FIG. 2 , the bottom, rear or proximal end  13  of the bolt  12  has an enlarged cylindrical section  14  and an opening  15  for the firing pin can be seen in the flat proximal face of the enlarged section  14 . 
     The striker assembly  11  consists of a striker or cocking piece  16 , a shroud insert  17  and housing  18 . A spring (not shown) is also part of the striker assembly. 
     The shroud insert  17  has a circular bore  19  therethrough configured to fit over the top of the enlarged cylindrical section  14  of bolt  12 . The exterior surface is somewhat elliptical in shape with left and right side lobes  20 ,  21  provided with axially aligned holes  22 ,  23 . As shown in  FIG. 3  the shroud insert  17  sits at the rear end of housing  18 . The striker or cocking piece  16  is generally a cylindrical rod which has lateral lobes  24 ,  25  each having a respective axial hole  26 ,  27  aligned with respective holes  22 ,  23  of the shroud insert  17 . The housing  18  has an appropriately shaped central channel to snugly seat the striker  16 . The housing  18  may also provide specially configured left and right side channels to seat the left and right side lobes  24 ,  25  and associated springs. The shape of the channels can be configured to suit the design of the striker  16 . 
     The opening to the channel  28  at the proximal end of the housing  18  allows the proximal end of the striker to protrude therethrough. The length of the striker is designed so that the distal end  30  is able to be pushed into contact with the firing pin which protrudes through the firing pin hole  15 . Springs (not shown) are typically provided between the proximal faces of the lobes  24  and  25  and the opposing inner faces of the housing  18 . Axial pins extend on the left and right hand sides of the assembly  11  between openings  22  and  26  and  23  and  27  respectively. These pins help align the striker  16  with the opposing face at the base end of the bolt  12 . When assembled the striker  16  is seated in the housing  18  with the left and right side springs compressed so that the rear end of the striker protrudes as far as it can beyond the rear end of the housing  18 . At the opposite end of the housing  18  the shroud insert  17  is located over the enlarged cylindrical section  14  of bolt  12  like a sleeve and is seated at the front end of the housing  18 . A cap or upper component can be located over the lower part of the housing  18  to fully house the striker  16 , springs and shroud insert  17 . 
     As shown in  FIG. 6 , firing pin  31  is a thin long cylindrical piece of metal  31  with a section of reduced diameter  32  at its front end which is configured to strike the back of a cartridge. In addition, the front section  32  is surrounded by a small return spring  33 . This ensures that the firing pin  31  is returned to its ready for firing position with its rear end  34  protruding slightly beyond the flat face of the bolt  12 . 
     Because of the reduced cross-sectional diameter of the front section  32  beyond the spring  33 , the diameter of the central bore  35  extending through the bolt  12  steps down into a smaller passage large enough to house the reduced diameter of the front section  32 . 
     The whole striker assembly would typically be located in part of a specially designed receiver assembly so that the rear end of the striker is able to be activated by a firing mechanism. 
     The striker assembly  11  and bolt  12  are able to axially slide to enable cartridge loading and discharge. As shown in  FIG. 2  the striker  16  may be provided with a sear  31  to allow for cocking of the striker. The cocking action may be provided using an outer sleeve having a window with a cam surface which is able to abut against the sear  31 . 
     In an alternative embodiment the opposing faces of the rear end  13  of the bolt  12  and the front end of the striker  16  may be provided with pin(s) and a co acting cam surface in order to provide for cocking of the striker assembly. 
     In operation when the striker  16  is fully cocked ready for firing, both springs are fully compressed. Activation of the firing mechanism results in release of the sear  27  and movement of the striker  16  towards the firing pin under the force of the expanding springs. To reload the firearm the striker can be pushed back to its ready for firing position by using the bolt handle to slide the bolt  12  backwards. The co acting pin(s) and cam surface will at the same time move the striker  16  into the ready for firing position. The bolt  12  is able to rotate relative to the shroud insert  17  to enable reloading without forcing similar rotation of the striker assembly  11 . As previously outlined the firing pin can be located for either a centre firing or rim firing action. 
     The design of the shroud and striker, spring and shroud insert may be changed as long as the striker is kept as a separate part from the bolt  12 . 
     The design of the bolt in the above-described preferred embodiment allows the bolt  12  to rotate because there is only a small axial hole through it to house the firing pin. If the bolt also contained a spring and spring support for a rim fire firearm the bolt is not able to rotate because the front half of the bolt must be cut away to allow the top cartridge in a magazine to be partially aligned with the chamber. 
     Referring to  FIG. 7  the striker assembly  39  shown consists of a bolt body  40 , a firing pin return spring  41 , a firing pin  42 , a striker  43 , a main spring  44  and a shroud  45 . 
     The shape of the striker  43  is in contrast to the striker  16  shown in  FIG. 2 , generally a cylindrical bolt shape with a cylindrical head instead of lobes  24  and  25 . The spring  44  fits over the proximal end of the striker  43  and together with the striker  43  fits within shroud  45 . The shroud insert  17  is eliminated from this embodiment. 
     As shown in  FIG. 8  the striker  43  is positioned behind the bolt body  40 . The bolt body  40  is provided, as more clearly shown in  FIG. 7 , with an offset centre axial bore (rim fire version) sized to receive the firing pin  42 . 
       FIG. 9  shows a close up view of the shroud  45  attached to bolt  40 . In this Figure the striker  43  is in the firing or cocked position. 
     As shown in  FIG. 9  the proximal end of the bolt body  40  has in this case been threaded  50  to allow the shroud  45  to be attached to the bolt body  40  while still allowing the shroud  45  to rotate relative to the axis of the bolt body  40 . 
     The striker  43  and main spring  44  are assembled within the shroud  45  such that the main spring  44  is constrained between the rear inner wall  46  of the shroud  45  and the larger diameter  46  of the striker  43 . 
     The firing pin  42  and firing pin return spring  41  are assembled within the bolt body  40  such that the firing pin  42  has its pin head  49  protruding from the rear of the bolt body  40 . 
     Reference to  FIG. 10  shows the striker in the fired or uncocked position. Thus it can be seen how the head of the striker  43  now contacts the head of the firing pin  42 . 
     The assembly  39  shown in  FIGS. 7-10  would typically be located in a receiver assembly shown in  FIG. 11 , so that the striker  43  is able to be released from a ready to fire or cocked position as shown in  FIG. 9  and allowed to be driven by the energy stored in the main spring  44  into a fired or uncocked position as shown in  FIG. 10 . 
     The assembly  39  shown in  FIG. 8  is able to axially slide within the receiver assembly shown in  FIG. 12  to enable loading and unloading of cartridges. 
     When using compression spring/s as the spring means within the assembly in  FIG. 9  the cocking action may be provided by a cam relationship between the bolt body  40  and the striker  43  such that when the bolt body  40  is rotated to the open position the striker  43  is forced towards the rear of the shroud  45  and thus compresses the main spring/s. 
     When using extension spring/s as the spring means within the assembly in  FIG. 9  the cocking action may be provided by a cam relationship between the bolt body  40  and the striker  43  such that when the bolt body  40  is rotated to the open position the striker  43  is forced towards the rear of the shroud  45  and thus extends the main spring/s. 
     The cocking action may be provided by forcing the striker  43  to be restrained while the bolt body  40  is pushed forward into the closed position prior to moving the bolt body  40  into the locked position. 
     Referring to another embodiment of the invention shown in  FIG. 13 , a disassembled assembly  59  consists of a bolt body  60 , a firing pin  61 , a striker  62 , a main spring  63  and a shroud  64 . 
     In this embodiment the striker  62  is in the form of a tubular structure with a lower leg portion  58  extending axially from a proximal edge thereof. Additional legs may be provided around the periphery of the striker  62  as shown in  FIG. 14 . Spring  63  is then able to be held in the space provided within the confines of the legs  58 . 
     Referring to  FIG. 14  which shows a close up of the assembly  59  shown in  FIG. 13 , the striker  62  is shown in the cocked position. 
     As shown in  FIG. 14  the striker  62  is positioned behind the bolt body  60 . The bolt is provided, as more clearly shown in  FIG. 13 , with an off centre axial bore (rim fire version) sized to receive a firing pin  61 . 
     As shown in  FIG. 14  the proximal end of the bolt body  60  has in this case been threaded  65  to allow the shroud  64  to be attached to the bolt body  60  while still allowing the shroud  64  to rotate relative to the axis of the bolt body  60 . 
     The striker  62  and main spring  63  are assembled within the shroud  64  such that the main spring  63  is constrained between the rear inner wall  68  of the shroud  64  and a counter bored face ( 67 ) of the striker  62 . 
     The firing pin  61  is assembled within the bolt body  60  such that the firing pin  61  protrudes from the rear of the bolt body  60 . 
     The bolt body  60  has been provided with a protrusion  69  which in this case has been used as a cam to force the striker  62  to compress the main spring  63  against the rear inner wall  68  of the shroud  64 . In this state the striker  62  has been prevented by the edge  66  of the protrusion  69  from striking the firing pin  61  until the bolt body  60  has been rotated into a position that does not impede the travel of the striker  62 . This position would then be considered the locked position when the bolt body  60  has been closed on a firing chamber. 
     According to another embodiment of the present invention shown in  FIGS. 15 to 19 , an assembly  56  shown in  FIG. 15  consists of a bolt body  70 , a firing pin return spring  71 , a firing pin  72 , a striker  73 , a main spring  74 , a safety catch  76  and a shroud  75 . 
     In this embodiment the striker  73  has a different configuration to those strikers of previous embodiments. In contrast the striker  73  is essentially a cylindrical rod which has a thin collar or ring  55  at a position slightly closer to the proximal end than the distal end thereof. A peripheral pin  54  is located on the distal side of the collar  55  and extends from the periphery thereof. 
     As shown in  FIG. 16  the striker  73  is positioned behind the bolt body  70 . The bolt body  70  is provided with a central axial bore sized to receive the forward portion of the striker  73 . In this case the striker  73  has been forced to compress the main spring  74  between the rear wall  77  of the shroud  75  and the rear face  78  of a flanged portion of the striker  73 . The head  79  of firing pin  72  protrudes from the front wall of the central bore of the bolt body  70 . 
     As shown in  FIG. 17  the striker  73  is positioned behind the bolt body  70 . In this case the striker  73  has been forced by the stored energy in the main spring  74  to impact upon the front wall of the central bore of the bolt body  70  thus impacting upon the firing pin  72 . 
     As shown in  FIG. 18  the bolt body  70  is in a position such that the cam face  85  is in contact with a pin  84  that has been provided on the striker  73 . 
       FIG. 19  shows that by turning a bolt handle  86  the bolt body  70  will rotate and allow the cam surface  85  to act upon the lateral pin  84  and thus force the main spring  74  to be compressed between the rear wall  77  of the shroud  75  and the rear face  78  of a flanged portion of the striker  73 . 
     According to other embodiments of the invention the rear or root end of the bolt will be threaded but not fixed into the shroud insert which in turn will be pinned or screwed to the housing. 
     It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or in any other country. 
     In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.