Abstract:
A replacement bolt action assembly useful for converting a gas operated paintball marker gun having an open bolt type action to a closed bolt type action is provided. The open bolt type action includes a combination open bolt and hammer assembly releaseably containable in the marker gun body, an actuator (trigger) assembly disposable in the marker gun frame in mechanical communication with the bolt and hammer assembly, for releaseably holding the bolt and hammer assembly in a cocked configuration; and a pressure control assembly in mechanical communication with the actuator assembly and in gas flow communication with the bolt and hammer assembly. The present invention can be provided as a kit for converting or replacing the actions of certain existing paintball marker guns to close bolt type actions without having to modify the structure of the existing gun&#39;s receiver or marker body.

Description:
The present invention claims the benefit of prior filled U.S. Provisional Patent Application Ser. No. 60/302,201, filed Jun. 29, 2001, and incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention is in the field of mechanical guns and projectors in which the projectile impelling apparatus utilizes a nonexplosive propelling agent. More specifically, the present assembly relates to devices provided with a chamber for containing pressurized gas and include a check valve to admit or release the gas from the chamber to cause the projectile to be positioned in or expelled from a paintball gun. 
     BACKGROUND OF THE INVENTION 
     “Paintball” is a currently popular recreational sport in which members of opposite teams attempt to mark opponents with paint, thereby removing them from the game. Marking is accomplished by using a paintball marker gun to shoot a projectile (paintball) containing paint or other appropriate marking material at an opponent. Paintballs are spherical capsules filled with paint or other marking material which burst upon impact. Upon contact with a player, the paintball ruptures, thus marking the player. Once a player is marked, he/she is out of the game. 
     A variety of different types of paintball marker guns exist in the field, using a variety of mechanisms for accomplishing their purpose of projecting paintballs. Two of the types of actions used on marker guns are the open bolt action and the closed bolt action. The open bolt type of action is used on simple, relatively inexpensive types of marker. In the open bolt action, the gun body comprises two parallel tubular bores. The upper bore contains the bolt, while the lower bore contains the hammer. The bolt and hammer components are connected together, allowing their moving parts to move in concert. The bolt and hammer assembly is held in the cocked position via a trigger sear, which catches the hammer portion of the assembly. In this position, the breach is open and a paintball is able to drop into position in front of the bolt. When the trigger is pulled, the sear releases the hammer and a spring drives the hammer and bolt forward. As the bolt moves forward, it chambers a paintball into the barrel of the marker gun. Simultaneously, the hammer moves forward to strike a poppet valve as the bolt closes on the chamber. The poppet valve releases a burst of high pressure gas into and through the bolt, expelling the paintball from the barrel. A bleed-off of the burst of high pressure gas then propels the hammer and bolt backwards. The hammer is then caught by the trigger sear, and the marker is again in a cocked configuration and ready to be fired again. This type of action is called an open bolt action because when the marker is in the cocked configuration the bolt is in the open position. Because of its early and inexpensive design, marker guns utilizing the open bolt action represent a significant proportion of the marker guns in use. 
     However, open bolt action has certain disadvantages. Since the paintball is forcibly moved forward by the bolt milliseconds before the air release to the barrel, the paintball may be damaged by causing distortions in the paintball&#39;s surface. This leads to adverse effects on the paintball&#39;s flight path and decreases accuracy. Another problem occurs when the bolt catches a paintball that is halfway loaded and chops it in half (“ball chop”). This can coat the barrel with paint, greatly ruining accuracy and potentially jamming the marker. This jamming requires the marker be disassembled for cleaning before continued use. 
     The closed bolt action overcomes these disadvantages. The closed bolt action differs from the open bolt action in that in the closed bolt action, when the marker gun is in the cocked configuration the bolt is in the closed position, and a paintball is already chambered in the barrel. Also, in a closed bolt action, the hammer is no longer connected to nor moves in concert with the bolt. Because when the gun is fired, only the hammer moves, there are fewer inertial forces at play during the actual discharge of the marker. Additionally, the paintball is not impacted by the bolt immediately before it is discharged from the marker gun, and therefore, the paintball should experience less surface distortion. This combination of fewer inertial forces and reduced distortion of the surface of the projectile should improve precision and accuracy of a closed bolt marker over the same marker using an open bolt action. 
     Examples of paintball marker guns used in the field include Anderson, U.S. Pat. No. 5,515,838 (paintball gun with a passage for porting pressurized gas to a ball projectile); Lukas et al., U.S. Pat. No. 5,613,483 (a gas powered gun with a piston and cylinder assembly for ejecting projectiles from the gun) and Lotuaco, III, U.S. Pat. No. 6,065,460 (gas-powered paintball gun with two pressure regulators; one for supplying lower pressure for loading paintballs and one for high pressure for expelling the paintball from the barrel.) 
     Currently, the investment to own even an open bolt action marker gun is substantial. Moving to the next level of marker gun with a closed bolt action, is an even greater expense. Therefore, the field has been motivated to develop means for converting or modifying for a number of purposes, including converting an open bolt action marker gun to closed bolt action type gun. 
     One example of a conversion kit is Fusco, U.S. Pat. No. 5,503,137. Fusco describes a conversion kit for converting a pump-action type compressed gas gun to a semi-automatic type compressed gas gun. The kit includes an actuating mechanism, a gas distributing mechanism, and an activating mechanism. The parts are removably connected to the gun, allowing for the gun to be returned to its original configuration upon removal. Another attachment to modify a paintball gun is described by Jones, U.S. Pat. No. 5,413,083. This attachment allows the gun to fire in automatic, semiautomatic or any other pattern of fire. The attachment includes a mechanical mechanism for manipulating a protrusion on the gun, such as the bolt handle, a programmable pulse generator for determining the pattern of fire, and an electromagnetic device for converting signals from the pulse generator into a mechanical motion for driving the mechanical mechanism. 
     Therefore, it would be beneficial to enable the owner of an open-bolt marker gun to convert the marker to a closed bolt marker, and avoid the expense of having to purchase a new marker gun in order to take advantage of closed bolt action technology. It would be further beneficial if the conversion did not require the structural modification of the original marker gun, so that the marker gun could be returned to its original configuration. 
     SUMMARY OF THE INVENTION 
     The present invention is a closed bolt action assembly for an existing gas operated paintball marker gun. Typically, a marker gun includes two primary structural components: the receiver (or marker gun body) and the trigger group (or marker gun frame). The present closed bolt action assembly can be used in the production of new units of the existing paintball marker gun or it can be used to replace the action assembly in a prior production unit. A paintball marker gun typically is made up of two major structural components: a marker gun body and a frame. Existing paintball marker guns that comprised body and frame combinations that were compatible with the present invention without structural modification of the body or frame include: the KINGMAN SPYDER™, and AVALON&#39;s GT COMMANDO. Other existing marker guns with which the present invention is intended to be compatible include the REBEL™ by 32DEGREES; PMI&#39;s PIRANHA, NPS&#39;s GT2000, and VIEWLOADER&#39;s GENESIS. It is anticipated that the present invention will be generally compatible with any paintball marker gun having receiver and frame structural characteristics analogous to these marker guns. 
     The present closed bolt action assembly comprises a combination bolt and hammer assembly, an actuator assembly and a pressure control assembly. The bolt and hammer assembly is releaseably containable in the marker gun body. The marker body is a pair of parallel cylindrical tubes integrally fixed together along a length of their outer surfaces. The marker body in turn is mounted on the marker gun frame in an “over and under” configuration. The actuator assembly is disposed in the marker gun trigger group or frame in mechanical communication with the bolt and hammer assembly. The actuator assembly releaseably holds the bolt and hammer assembly in a cocked configuration prior to discharge of the marker gun. The actuator assembly includes the trigger for the gun. The pressure control assembly is in mechanical communication with the actuator assembly and in gas flow communication with the bolt and hammer assembly. The pressure control assembly controls low pressure gas flows to drive certain operations of the bolt and hammer assembly, such as opening and closing the bolt. 
     The bolt and hammer assembly comprises separate bolt and hammer components which operate independently of each other when they are installed in the marker body. The bolt is installed in the upper or “over” tube of the marker gun body, and the hammer is installed in the lower or “under” tube. The bolt opens the breech of the marker gun allowing a paintball projectile to be loaded into the marker gun. The bolt then closes the breech and chambers the projectile into the barrel of the marker gun. The operation of the bolt is controlled by the low pressure gas controller assembly. The action of the hammer operates a high pressure gas valve to open a high pressure gas flow path between a source of high pressure gas and the chamber of the barrel. A portion of the high pressure gas flow path is through the bolt head of the bolt when the bolt is in the closed position. 
     The bolt of the bolt and hammer assembly is further comprises an air ram, mounting means, a bolt head and low pressure gas lines. The air ram is pneumatic cylinder housing a double action piston. The piston is double action in that it can be driven in two directions. A piston shaft is attached to the piston and protrudes from one end of the pneumatic cylinder of the air ram. The piston shaft is driven by movement of the piston within the air ram cylinder. The other end of the pneumatic cylinder is attached to an air ram mounting block. The ram mounting block in turn is received into the over tube of the gun body proximate its breech end, and retained there by a locking pin. Two low pressure gas ports are disposed on the air ram in communication with an interior space of the pneumatic cylinder, one each for driving the piston in either direction. At the front end of the air ram, a bolt head is attached to the protruding end of the piston shaft. The term “front” as used herein regarding a structure or component refers to that portion of the thing most proximate the muzzle of the barrel of the marker gun in which it is installed. The bolt head is driven by movement of the piston within the pneumatic cylinder of the air ram. Additionally, a bolt sealing disk is disposed proximate the front end of the ram. The sealing disk provides stability to the front end of the air ram and pneumatic isolation of the bolt head from the rest of the bolt. 
     The bolt head is substantially a cylinder having a central axis, a solid circumferential surface. The front end of the bolt head is the bolt-face end. The bolt face is typically concave to compliment the shape of the paintball projectile. The back end of the bolt head engages the piston shaft end of the air ram. An inside-mating surface is provided along at least a portion of the central axis at the back end of the bolt head to receive the piston shaft end. A plurality of gas flow passages are disposed in the bolt head, passing through the bolt-face and breech ends of the bolt head. The passages are a portion of the high pressure gas pathway that supplies propellant to project a chambered paintball from the barrel of the marker gun. 
     The ram mounting block is substantially cylindrical and is closely received into the lumen of the over tube of the marker body when installed. The ram block has a longitudinal tab along at least part of its outer surface in parallel with the axis of the cylinder of the ram block. On installation of the bolt, the tab is received into a portion of a slot in the rear or breech end of the marker body, which slot is open to the interior space or lumen of both the over and under tubes of the marker body. The ram block tab incorporates a complementary part of a detent by which the bolt and hammer assembly is retained in position in the marker body after its installation. 
     The hammer assembly of the present invention also has a generally cylindrical configuration and comprises a cylindrical striker in axial alignment with a cylindrical tensioner block and a bias spring disposed along the axis between the striker and the tensioner block. The bias spring functions to axially separate the striker from the tensioner block. The striker has solid front face for impacting a high pressure gas flow control valve to cause the valve to open. The rear end of the striker has a coaxial lumen along a portion of its axis for receiving one end of the bias spring. The front face of the tensioner block has a coaxial lumen along a portion of its axis for receiving the bias spring. 
     A detent complimentary to the detent on the tab of the ram block defines the upper surface of the tensioner block. A locking pin passing through the marker body and simultaneously engaging the detents on both the ram block and the tensioner block retains the bolt and hammer in the marker body. Additionally, the tensioner block has a pre-loading means for adjusting the normal bias of the bias spring. Typically this is accomplished by having an adjusting screw pass through the axis of the tensioner block from its rear surface to impinge on the end of the bias spring received in the lumen of the block. Turning the screw alters the normal length of the bias spring and hence the initial bias load or force exerted by the bias spring. 
     Cocking the marker gun causes the striker to be drawn toward the tensioner block against the force of the bias spring. Cocking the marker gun is manually accomplished by drawing the cocking rod to its fully extended position. When the striker has been drawn a distance toward the tensioner block to store sufficient energy in the bias spring, a trigger notch on the lower surface of the striker engages a sear lever on the marker gun frame and is retained at this position inside the under tube. In this configuration, the hammer of the marker gun is cocked. Upon operation of the sear lever to disengage it from the trigger notch, the striker flies forward under the force of the bias spring and impacts the high pressure gas flow valve (e.g., a poppet valve) causing it to operate and open a high pressure gas flow path to the over tube. Once the high pressure valve is operated, a bleed off pressure from the high pressure gas flow path to the lumen of the under tube in front of the striker causes the striker to be drawn back again against the force of the bias spring until the hammer is again cocked. This is how the hammer is automatically cocked after the marker gun is discharged. 
     However, before the action is able to automatically re-cock the marker gun after being discharged, it must be manually cocked before the first time it is discharged. This is accomplished by operation of a manual cocking rod. The manual cocking rod is a metal rod having two ends. The front end of the cocking rod freely passes through a hammer link pin mounted to the top surface of the striker. The front end of the cocking rod has a stop at its terminus to prevent its being withdrawn from and for engaging the link pin. The link pin not only serves to couple the cocking rod to the striker, but also serves to maintain the striker in the proper orientation, so that the trigger notch is always bottom most on the striker. The length of the cocking rod slidably passes through the air ram mounting block, parallel to the axis of both the over and the under tubes. The rear end of the cocking rod extends outside the marker body and is adapted to be manually gripped and withdrawn from the marker body to place the hammer of the bolt and hammer assembly in a cocked configuration. 
     In an alternative embodiment, the cocking rod may be completely integrated into the hammer assembly. In this embodiment, the cocking rod does not engage the link pin, but rather, is disposed to engage a striker insert received in the bore of the striker/hammer. The cocking rod then extends from the marker gun by passing through the tensioner block rather than the air mounting ram. 
     The actuator assembly is installed in the marker gun trigger group or frame as part of the discharging mechanism of the marker gun. The actuator assembly comprises the trigger of the marker gun, which when the present invention is installed, is in direct mechanical communication with the pressure control assembly, and with the means for releaseably holding the bolt and hammer assembly in a cocked configuration (the trigger sear lever). The actuator mechanism includes a link rod which mechanically connects the trigger to the pressure control assembly. Alternatively, the actuator assembly has been practiced using a slide switch to mechanically connect the trigger to the pressure control assembly, instead of the link rod. 
     The pressure control assembly is in part installed on the marker gun frame and in part on the marker body. The pressure control assembly comprises a slide operated, two-way, low pressure gas valve in direct mechanical communication with the trigger of the actuator assembly. The low pressure gas valve is mounted to the marker frame using a mounting bracket or a stand-off. Three low pressure gas lines are connected to the low pressure valve. The other end of the incoming or primary gas line is connected to a low pressure gas regulator which provides low pressure gas for the gas pressure control assembly. In turn, the low pressure gas regulator is connected to the marker gun body in gas flow communication with the high pressure gas source of the marker gun. The low pressure gas regulator is adjustable to regulate an amount of reduction of gas pressure accomplished by the regulator. 
     The other two low pressure gas line are connected to the outputs of the low pressure valve. These are the first and second secondary gas lines. At its other end, the first secondary gas line is connected in gas flow communication with the piston return port on the air ram, and the second secondary gas line is connected in a similar manner in gas flow communication with the piston extension port on the air ram. 
     The present invention may be used to convert an existing paintball marker gun from an open bolt action to a closed bolt action. The process for accomplishing this comprising the steps of removing the existing bolt and hammer assembly from the marker gun and installing the present combination bolt and hammer assembly in the marker gun in it place. Replacing the existing trigger of the marker gun with the present actuator assembly, and installing the pressure control assembly on the marker gun, connecting the pressure control assembly to the actuator assembly and to the bolt and hammer assembly to provide a paintball marker gun having a closed bolt action. This conversion is accomplished without modification of the existing marker gun body or frame. The present invention is provided as a kit to facilitate a user&#39;s converting an open bolt action paintball marker gun to a closed bolt action. The kit includes the closed bolt action assembly described herein, instructions and container or package for containing the closed bolt action assembly and the instructions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial cross-sectional plan view of the major components of the present invention, showing their relationship to a marker gun receiver and trigger group. 
     FIG. 2A is a partial cross-sectional view of the bolt and hammer assemblies of the present invention. 
     FIG. 2B is a partial cross-sectional view schematic illustrating how the bolt and hammer assemblies are installed into a marker gun receiver. 
     FIG. 3 is a rear elevation view of an air ram mounting block and a hammer tensioner block showing the over and under relationship of the two components as installed in the receiver of the marker gun. 
     FIG. 4 is a cross-sectional view of an alternative hammer assembly for use in the present invention. 
     FIG. 5 is a partial cross-sectional view of the trigger group and the components of the pressure control assembly that attached to it. 
     FIG. 6 is a partial cross-sectional view showing the low pressure gas line connections and an alternative mounting means for the two-way low pressure gas valve. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, the details of preferred embodiments of the present invention are graphically and schematically illustrated. Like elements in the drawings will be represented by like numbers, and similar elements will be represented by like numbers with a different lower case letter suffix. 
     The present invention is a closed bolt action assembly for a gas operated paintball marker gun  10 . As shown in FIG. 1, the marker gun  10  includes a marker gun body or receiver  14 , and a marker gun frame or trigger group  30 . The present closed bolt action assembly is installed in or attached to the marker gun receiver  14  and frame  30 . The present closed bolt action assembly is installable into an existing marker gun receiver/frame combination, to replace a defective existing action assembly or to convert an open bolt action assembly to a closed bolt action assembly, without modification of the existing receiver/frame combination. Existing marker gun receiver/frame combinations that are practicable with the present invention include the KINGMAN SPYDER™ and other as noted above. 
     FIG. 1 shows a marker gun  10  having a receiver/frame combination practicable in the present invention. The receiver  14  is a duel lumen tube containing two parallel bores in an “over &amp; under” configuration when mounted on the trigger group or frame  30 . The upper or “over” bore  15  mounts the barrel  16  of the marker gun at its front end and includes the breech  17  where paintball projectiles  18  are loaded into the marker gun  10  from a magazine  19  or similar loading mechanism. Paintball magazines and similar projectile loading mechanisms are known in the field and are readily adaptable for practice on the present invention by the ordinaiy skilled artisan. The lower or “under” bore  20  houses the high pressure gas chamber  21  and mounts tAe high pressure gas input port  22 , which is in turn connected to a high pressure gas source (not shown). The “under” bore  20  also houses the high pressure gas valve  24  which controls high pressure gas flow through the high pressure gas passage  26  between the over bore  15  and the under bore  20 . The receiver  14  and any attachments are mounted on the trigger group or frame  30  in a vertical orientation with the over bore  15  uppermost. The marker gun trigger group attaches to the receiver  14  by way of fasteners  32  and is in mechanical communication with the receiver  14  by way of the trigger sear lever  34 . 
     The present open bolt action assembly itself comprises a combination bolt and hammer assembly  40 , an actuator assembly  44  and a pressure control assembly  48 . As shown in FIG. 2A, the bolt and hammer assembly  40  comprises two major subassemblies: a bolt  52  subassembly and a hammer  54  subassembly. The bolt and hammer assembly  40  is removably installed in the marker gun receiver  14 , with the bolt  52  installed in the lumen of upper or “over” bore  15 , and the hammer  54  installed in the lumen of the lower or “under” bore  20 . The action of the bolt  52  provides for opening and closing the breech  17  to automatically load a paintball projectile  18  into the marker gun  10  from an attached magazine  19 . The bolt  52  then chambers the projectile  18  into the barrel  16  of the marker gun  10 . 
     The bolt  52  is comprised of a bolt head  58 , and an air ram  62  and an air ram mounting block  64 . See FIG.  2 A. The air ram  62  is a pneumatic cylinder  63  housing a double action piston  66 , the shaft  68  of which protrudes from the first or front end  70  of the pneumatic cylinder  63  of the air ram  62 . The bolt head  58  is connected to the front end of the piston shaft  68 . The ram mounting block  64  fixedly receives the second or rear end  72  of the air ram  62  and releaseably retains the bolt  52  in the marker body  14 . Two low pressure gas cylinder ports  74  &amp;  75  are disposed in communication with the interior space of the pneumatic cylinder  63  to deliver low pressure gas proximate each end of the ram  62 . A bolt sealing disk  78  is disposed proximate the front end  70  of the air ram  62 . The sealing disk  78  provides structural stability to the air ram  62  and pneumatic isolation of the bolt head  58  from the air ram  62  and ram mounting block  64  within the over bore  15 . In a preferred embodiment, the sealing disk  78  utilized an “O”-ring  80  retained about the circumference of the disk  78  to accomplish its sealing feature. Other means of accomplishing the sealing feature of the disk  78  are known to one of ordinary skill in the art and are practicable in the present invention. The air rams  62  practiced in the preferred embodiment were commercially acquired from ANS and J&amp;J. These vendors and/or other for certain component parts of the present invention are known to the ordinary skilled artisan. 
     In operating the bolt  52 , when low pressure gas is applied to the rear cylinder port  75  the piston  66  is moved toward the front end  70  of the pneumatic cylinder  63 . This action extends the shaft  68  and the attached bolt head  58  forward into the breech  17  and against the chamber of the barrel  16 . A paintball projectile  18  positioned in the breech before this action is moved forward by the bolt head  58  and chambered into the barrel  16 . With the bolt head  58  in this position, the breech  17  is sealed and the bolt  52  is in the closed configuration. The bolt  52  is held closed in the breech  17  during firing by the pressure differential across the bolt head  58 , since the highest gas pressure during firing initially occurs at the rear of the bolt head  58  and expands through it into the barrel  16 . When low pressure gas is applied to the front cylinder port  74  the piston  66  is moved toward the rear end  72  of the pneumatic cylinder  63 . This action retracts the shaft  68  into the pneumatic cylinder  63  and withdraws the bolt head  58  away from the barrel  16 , and backward past the breech  17 . With the bolt head  58  in this position, the breech  17  is opened and the bolt  52  is in the opened configuration. 
     The bolt head  58  is cylindrical, having a central axis and a solid circumferential surface. The front end of the bolt head  58  is the bolt-face  84 . Preferably, the bolt face  84  is contoured to at least partially complement the shape of the projectile  18  it loads into the barrel  16  (see FIG.  2 A). The ram end  86  of the bolt head  58  has an inside-mating surface  88  along at least a portion of the central axis of the bolt head  58 , for receiving and attaching to the piston shaft  68  of the air ram  62 . Preferable, the mating surface  88  is threaded and disposed to engage a complementary thread on the front end  69  of the piston shaft  68 . A plurality of gas flow passages  90  pass through the bolt head  58  communicating between the bolt-face  84  and ram end  86  of the bolt head  58 . 
     The ram mounting block  64  is substantially cylindrical and is closely received into the lumen of the over tube bore  15  of the receiver  14  when installed, e.g (See FIG.  2 B). The ram block  64  has a longitudinal tab  65  in parallel with the axis of the block  64  and extending radially from its outer surface. On installation of the bolt  52 , the tab  65  is received into a portion of the receiver slot  28  in the rear or breech end of the receiver  14 . The receiver slot  28  is open to the interior space or lumen of both the over and under bores  15  &amp;  20  of the marker body  14 . The ram block tab  65  incorporates a complementary part of the detent  94  by which the bolt and hammer assembly  40  is retained in position in the marker receiver (marker body)  14  after its installation. 
     The hammer subassembly  54  functions to operate the high pressure gas valve  24  to open the high pressure gas flow passage  26  between the high pressure gas chamber  21 , through the bolt head  58  to the barrel  16  on the marker gun  10 . The hammer  54  is comprised of a cylindrical striker  100  in axial alignment with a cylindrical tensioner mount  106 . A hammer spring  112  is disposed in axial alignment between striker  100  and the tensioner  106 . When the hammer  54  is retained in place in the under tube bore  20 , the tensioner block  106  is fixed in place and the striker  100  is slidable within the under tube bore  20 . The bias of the hammer spring  112  acts to axially separate the striker  100  away from the tensioner mount  106 . The striker  100  has an impact face  102  and a rear face  103 . The striker also has a coaxial lumen  104  open at its rear face  103  and extending along a portion of its axis for receiving the hammer spring  112 . The tensioner mount  106  has a tensioner front face  108  and a tensioner rear face  109 , with a coaxial lumen  110  open at its front face  108  and extending along a portion of its axis for receiving the bias spring  112 . The tensioner mount  106  has a pre-loading means  116  (velocity adjustment screw) for adjusting the bias or force the hammer spring  112  exerts on the striker  100  and the tensioner  106 . In a preferred embodiment, the tensioner mount  106  had a threaded aperture  118  which received a complementary threaded adjusting screw  120  extended through the aperture  118 . The front screw end  122  impinged on the hammer spring  112  received in the tensioner lumen  110 . The rear screw end  124  was slotted as a manual manipulating means for altering the distance the adjusting screw  120  extended into the tensioner lumen  110  to pre-load the bias of the hammer spring  112 . Other means of accomplishing a manipulating means are known to the ordinary skilled artisan that are practicable in the present invention, such as knurled screws and winged screws. 
     Additionally, the tensioner mount  106  has a detent  95  complimentary to the detent  94  on the tab  65  (see FIG. 3) of the ram block  64 . A locking cross pin  96  passes through a pin aperture  97  in the marker receiver  14  and simultaneously engaging the detents  94  &amp;  95  on both the ram block  64  and the tensioner mount  106  to retain the bolt and hammer in the marker body  14 . See FIG.  2 A. 
     Although the striker  100  is cylindrical, in a preferred embodiment its axial orientation within the under bore  20  was fixed. In that preferred embodiment, the striker  100  had a trigger sear notch  105  in a portion of its outer surface. The trigger notch  105  engaged the trigger sear  34  on the marker gun frame  30  and retained it at this position inside the under tube  20 . In that configuration, the hammer  54  of the marker gun  10  was cocked. The trigger notch  105  was maintained in a downward most position relative to the position of the over bore  15  by means of a link pin  128  which protruded from the outer surface of the striker  100  opposite the trigger notch  105 . Upon movement of the striker  100 , the link pin  128  traveled in the bore slot  28  (see FIG. 1) between the over and under bores  15  &amp;  20  in the existing marker receiver  14 . 
     The bolt and hammer assembly  40  includes a means of manually cocking the hammer  54  to initiate the automatic cycling of the present closed bolt action This was accomplished in a preferred embodiment, wherein the link pin  128  was in operative communication with a manual cocking rod  134 . The manual cocking rod  134  slidably passed through a rod passage  140  in the ram mounting block  64 , parallel to the air ram  62 . The cocking rod  134  had its first or front end  135  inside the marker body  14  in mechanical communication with the link pin  128  on the striker  100 . The cocking rod front end  135  has a stop means  138  at its terminus to engage the link pin  128  when the cocking rod  134  is manually operated, but to disengage the link pin  128  when the striker  100  is itself otherwise moved. The link pin  128  not only serves to couple the cocking rod  134  to the striker  100  hut also serves to maintain the striker  100  in the proper orientation the under bore  20 ,  50  that the trigger notch  105  is always bottom most on the striker  100 . The second or rear end  136  of the cocking rod  134  extended through the ram block  64  and outside the marker receiver  14 . The second or rear cocking rod end  136  was adapted to be manually gripped and withdrawn from the marker receiver  14  to place hammer  54  of the bolt and hammer assembly  40  in a cocked configuration. FIG. 3 is a rear view of the air ram mounting block  64  and the hammer tensioner mount  106  showing the over and tinder relationship of the two components as installed in the receiver  14  of the marker gun  10 . 
     In an alternative embodiment shown in FIG. 4, the cocking rod  134   a  may be completely integral to the hammer assembly  54 , i.e., the cocking rod disposed completely as part of the hammer assembly  54 . In this embodiment, the cocking rod  134   a  does not engage the link pin  128  or any portion of the bolt assembly, but rather, is disposed to engage a striker insert tube  130  received in the lumen  104  of the striker  100 . The cocking rod  134   a  then extends from the marker gun receiver  14  by passing through the tensioner mount  106  and velocity adjuster  116   a  rather than the air ram mounting block  64 . The striker insert tube  130  moves in unison with the striker  100 . In the preferred embodiment shown, a friction link provided by the O-ring  107  connects the striker  100  and striker insert tube  130  allowing them to moves in unison in the under bore  20  of the receiver  14 . As the striker  100  and insert tube  130  combination travel forward and backward in the under bore  20 , such as when the marker gun  10  is being fired, the striker insert  130  slides freely over the cocking rod  134   a  in the striker hollow  131 . Preferably, the cocking rod  134   a  remains stationary during firing. When the striker  100  is in a forward position (i.e., the hammer spring  112  is in an extended or uncompressed configuration), and the gun  10  needs to be manually cocked (i.e., the striker  100  brought to the back position so that the trigger notch  105  may engage the trigger sear  34 ), the cocking rod  134   a  is moved backwards by pulling backwards on the cocking knob  137  attached to the cocking rod rear end  136 . This draws the cocking rod  134   a  through central bores  150  &amp;  151  in the thrust plate  122  and velocity adjuster  116   a  which each have holes through them allowing the cocking rod  134   a  to slide semi-freely through them. The resistance to movement encountered by the cocking rod  134   a  passing through these bores  150  &amp;  151  is not sufficient to hinder manually cocking gun  10 , but is sufficient to prevent the movement of the cocking rod  134   a  upon the automatic cocking of the gun  10 . When the cocking rod  134   a  is drawn backwards, the cocking rod stop  138   a , shown in this embodiment as an enlargement at the cocking rod front end  135  (which usually slides freely inside the striker insert  130 ), engages the rod seat  142  of the striker insert  130 . In the embodiment shown, the rod seat  142  is a reduced internal diameter of the back end of the striker insert tube  130 . This allows the striker  100  and insert  130  combination to be drawn backwards by the cocking rod  134   a . The link pin  128   a  maintains the axial orientation of the striker  100  and prevents it from rotating in the under bore  20  of the receiver  14 . 
     Also illustrated in this embodiment is a bumper pad  114  which may be incorporated into a hammer assembly to cushion or reduce the recoil of the striker  100  at the end of its backward travel. The bumper pad  114  was made of a rubber type material in the embodiment shown, but any other suitable materials as selectable by one of skill in the art may be used. The cocking knob  137  is illustrated as attached to the cocking rod rear end  136  by means of a set screw  141 . However, alternative mean for providing a cocking knob  137  at the cocking rod rear end  136  are known to the ordinary skilled artisan and are readily accomplishable in the present invention. For example, the cocking rod rear end  136  can end in a loop to facilitate its being manually grasped. 
     As shown in FIG. 5, the actuator assembly  44  is disposed in the trigger group (frame)  30  in mechanical communication with the bolt and hammer assembly  40 . As shown in  2 B, the actuator assembly  44  in combination with the trigger group acts to releaseably holding the hammer  54  in a cocked configuration. The actuator assembly  44  comprises a trigger  144  in direct mechanical communication with the pressure control assembly  48  and with the trigger sear  34 . The trigger sear  34  extends through the sear notch  35  (see FIG.  1 ), and is the means for releaseably holding the hammer  54  in a cocked configuration. A link rod  146  mechanically connects the trigger  144  to the pressure control assembly  48 . Alternatively, a slide arm  148  has been used to mechanically connect the trigger  144  to the pressure control assembly  48  using an appropriate mounting bracket  156   a , see FIG.  6 . 
     The pressure control assembly  48  is in mechanical communication with the trigger  144  of the actuator assembly  48 , and in gas flow communication with the bolt and hammer assembly  40 . The pressure control assembly  48  comprises a low pressure (L/P) gas valve  154  and mounting bracket  156 , a low pressure gas regulator  158 , and a plurality of low pressure gas lines. L/P pressure regulators practiced in a preferred embodiment of the present invention were the ANS JACKHAMMER™ and JACKHAMMER II™. Other L/P pressure regulators practicable in the present invention include PALMERS PURSUIT SHOP&#39;s ROCK REG™ and MINI ROCK™. SHOCKTECH is another manufacturer of LIP gas regulators. 
     In a preferred embodiment shown in FIG. 1, the L/P gas valve  154  was a slide operated, two-way valve. The L/P valve  154  was a two way valve in that it had a common input port  162  and two alternately selectable valve output ports  164 . The L/P gas valve  154  is operable to provide gas flow communication between the common input port  162  and one or the other, but not both, of the LIP valve output ports  164  The L/P valve used in the embodiment of FIG. 1 was manufactured by ANS and purchased over the counter. However, similar valves are commercially available and known to one of skill in the art, and are adaptable for practice in the present invention without undue experimentation. These include the PALMER QUICKSWITCH™, SHOCKTECH&#39;s THE BOMB™. Other sources of appropriate valves include WGP, KAPP and ACM. A port selector means  168  extended from the L/P gas valve  154  and mechanically communicated with the trigger  144  of the actuator assembly  44  via the link rod  146 . A bracket  156  was used to attach the LIP gas valve  154  to the marker gun frame  14  proximate the trigger  144 . 
     A primary or input L/P gas line  170  is connected between the L/P valve input port and the L/P regulator output port  178 . A first and a second secondary L/P gas lines  172  &amp;  172   a  are each connected between an L/P gas valve output port  164 , respectively, and the pneumatic cylinder  63  of the air ram  62 . The the first secondary L/P gas line  172  is connected to the piston return port  74  on the air ram  62 , and the second secondary L/P gas line  172   a  is connected to the piston extension port  75  on the air ram  62 . 
     The L/P gas regulator  158  is mounted at the front of the under bore  20  of the receiver  14  in gas flow communication with the high pressure gas chamber  21  The L/P gas regulator  158  takes high pressure gas from the high pressure gas chamber  21  and reduces the pressure to provide low pressure gas at its output port  178  to provide the low pressure gas requirements of the remainder of the pressure control assembly  48 . In a preferred embodiment, the LIP gas regulator  158  was mounted using an adapter plug,  160 , and was adjustable to regulate the amount of reduction of gas pressure accomplished by the L/P gas regulator  158 . 
     The present closed bolt action assembly was used to convert an existing paintball marker gun from an open bolt action to a closed bolt action in the following manner: 
     the existing bolt and hammer assembly was removed from the marker gun  10 , and the present bolt and hammer assembly  40  was installed in the marker gun  10  with out modification of the existing receiver  14 ; 
     the existing trigger was removed from the trigger group or frame  30  of the marker gun  10 , and replaced with the present actuator assembly  44 , again without structural modification of the existing marker frame  14 ; and 
     the present pressure control assembly  48  was installed on the marker gun  10 , and connected to the actuator assembly  44  and to the bolt and hammer assembly  40  as described above, to provide a paintball marker gun having a closed bolt action. 
     For the convenience of an end user, the present invention is provided as a kit for converting an open bolt action paintball marker gun to a closed bolt action The kit comprises the closed bolt action assembly of the present invention, instructions on how to accomplish the conversion, and a container  200  for holding the instructions, the present closed bolt action assembly and any ancillary parts or tools that may be desirable by one of ordinary skill in the art to include in the kit for the benefit of an end user. 
     While the above description contains many specifics, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of one or another preferred embodiment thereof. Many other variations are possible, which would be obvious to one skilled in the art. Accordingly, the scope of the invention should be determined by the scope of the appended claims and their equivalents, and not just by the embodiments.