Abstract:
An improved electronic pneumatic paintball gun, with an improved, simplified design incorporating an improved pneumatic hammer, electronic control circuit, pressure regulator, bolt design and cocking system for utilization in paintball guns or related devices. This paintball gun eliminates complex mechanical systems thus providing a consistent operation with low maintenance. The paintball gun utilizes low pressure to minimize damage to paint balls when fired and to the paintball gun&#39;s internal parts, plus increase the effective number of shots per tank.

Description:
TECHNICAL FIELD OF THE INVENTION 
   The present invention generally relates to marking devices and, more particularly, to an electronic pneumatic paintball game. 
   BACKGROUND OF THE INVENTION 
   The sport of paintball was developed back in the early 1980&#39;s. Paintball gun technology has developed rapidly since then, out-pacing all other paintball-related equipment. The evolution of paintball guns started with single shot pistols. Then the pump paintball gun was developed which still had to be manually re-cocked to load another paintball and set the hammer in the “ready-to-fire” position. Pump paintball guns were the standard paintball bun for a few years. Then Tippmann Pneumatics (U.S. Pat. No. 4,819,609) developed one of the first semi-automatic paintball guns. This design used air to push a spring-fired hammer back to the ready position after the gun was fired. This design is known as an open bolt blow back paintball gun because the hammer is blown back into the ready position and, since the bolt is connected to the hammer, the bolt is open allowing a ball to drop into the breech. 
   Just a short time after Tippmann developed the block back paintball gun, Glenn Palmer developed a closed bolt pneumatic paintball gun built using a pump paintball gun. This paintball gun used a pneumatic piston attached to a manually operated 4-way valve. After the paintball gun was fired, the trigger traveled an extra distance which activated the 4-way valve, shuttling air to the back side of the pneumatic piston. The piston then pushed the bolt and hammer back allowing another paintball to fall into the breech. Then the trigger was released and the 4-way valve shuttled air back to the front side of the piston, pulling the bolt closed and sealing the paintball into the breech, leaving the paintball gun ready to fire again. 
   It was found that a paintball fired from a closed bolt pneumatic paintball gun had a longer range and better accuracy than a paintball fired from an open bolt blow back paintball gun. The only problem with a closed bolt paintball gun was its complexity, which required a higher price tag. 
   Recently, electronics have been added to the closed bolt pneumatic guns in an attempt to simplify their mechanical complexity. Instead, electronics have complicated the situation further because many of the paintball guns upon which the electronic guns are based had poor designs that are not suitable for electronic automation. Current electronic paintball guns come in several different designs. Four out of five of them are open bolt designs, but they all are inadequate for the job, usually being overly complicated with many small and delicate parts with poor construction. 
   The electronic guns use electric solenoid valves which are pressure sensitive and easily damaged from the high air pressures often used in prior art paintball guns. Also the use of the unregulated air to move the bolt back and forth creates a problem when the ball gets caught by the bolt. The bolt can cut the ball in half causing the gun to stop working. Some electronic guns have hoses and delicate parts on the outside of the gun that can be hit and damaged by a paintball. But for the most part the prior art electronic guns use high end electronics and low end guns to try to make a high grade paintball gun. 
   The present invention corrects this problem with a design specifically developed from the ground up to be an electronic closed bolt pneumatic paintball gun and more particularly to be an improved electronic pneumatic paintball gun with an improved pneumatic hammer, electronic control circuit, pneumatics pressure regulator, bolt design and cocking system. All parts of the gun are built around a cartridge design for quick replacement of a malfunctioning part. This design combines electronics, reliable design functions, ease of maintenance, and simple construction. 
   SUMMARY OF THE INVENTION 
   The present invention provides an improved paintball gun which operates at a low internal pressure with minimal distortion and damage to the paintball when fired and increases the effective number of shots peak tank. It is reliable, has a reduced number of parts and is easily maintained. This is accomplished with the use of a simplified pneumatics pressure regulator, hammer system, ram, bolt and electronics. These and other features and advantages of the invention will be more readily apparent upon reading the following description of a preferred embodiment of the invention and upon reference to the accompanying drawings. 
   The present preferred embodiment paintball gun utilizes the technology of two existing patents. One is U.S. Pat. No. 5,791,328 (Aaron K. Alexander) which is a paintball gun valve that permits the paintball gun to fire a paintball with the use of air pressure that is much lower than any other paintball gun in use today and to increase the effective number of shots per tank by a factor of 2. All other valves require the use of an average of 300 psi or higher to work. This valve permits the gun to operate normally at 180 psi though, in testing, guns have been operated as low as 100 psi and still maintained the correct velocity of 300 fps on the ball. 
   The preferred embodiment also utilizes technology from U.S. Pat. No. 5,904,133 (Aaron K. Alexander &amp; Larry G. Alexander). This bolt-on chamber was designed to install on existing guns to help lower the operating pressure by increasing the volume of air stored in the valve chamber. It was intended to be used in conjunction with the valve in the patent previously referenced. The present gun is designed to run at low operating pressure without the use of such a bolt-on chamber, but adding it to the end of the valve chamber will in turn lower the operating pressure even further. 
   The current improved paintball gun design starts with the use of a new paintball gun body design. The main gun body design, in conjunction with the cartridge designs, is a major advance in paintball gun design. The design changes allow the body of the gun to be extruded to shape (in aluminum, for example) with the outside shape and three internal bores, whereas most prior art guns require that the internal bores of the gun be machined into the gun. This greatly lowers the cost of the gun body. Additionally, most of the major parts of the present invention that would be bolt-on parts for prior art guns are machined into the gun body, making the gun much stronger and more durable than previous gun designs. 
   One of the major design improvements of the present paintball gun design is that the gun&#39;s overall design is built around a cartridge system for ease of maintenance. Even though each component part can be maintained individually in an ideal environment, this paintball gun is designed to be repaired quickly in a tournament situation by replacing only the affected cartridge without having to completely tear the gun down and re-tune the gun once reassembled. This allows the player to get back onto the paintball field quickly. Having the design of the gun based around a cartridge system for replacement purposes also allows for another major design change. All prior art guns required the complete disassembly of the gun to access the internal parts of the gun. The present preferred design, with cartridges and a tubular structure, allows all internal components to be removed from the gun from both ends without removal of the grip, which has to be done on every prior art gun. The grip frame of the present invention has to be removed only to replace the solenoid valves and the circuit board, which should rarely be necessary. 
   The current design uses a new pressure regulator that lowers the already low input pressure into the gun so that the solenoid valves are not damaged by high air pressure. The regulator&#39;s design has fewer parts than previous regulator designs, giving it a much simpler construction and ease of maintenance. 
   There are two hammer systems designed to work with the present paintball gun to open the valve and release air from the valve to fire the paintball. On prior art pneumatic hammers systems, the hammer was attached to the front of the shaft of a pneumatic cylinder, commonly referred to as a pneumatic ram, which pushed the hammer against the valve to open it. The prior art systems were longer, took up more space, were fragile, and had a larger number of parts than the present invention. The two hammer systems used in this paintball gun use a hammer system where the hammer and the pneumatic ram have been combined into one piece, eliminating the long length and large size of the prior art systems and further simplifying the pneumatic hammer. 
   The pneumatic hammers of the present invention also use a sliding front u-cup, which reduces the friction below that achieved by prior art rams that use a stationary seal, which requires a highly polished smooth surface. The sliding u-cup removes the need for polishing and grinding the shaft of the ram, as done on all prior art pneumatic hammer systems and simplifies construction of the hammer. 
   The hammer systems embodiments disclosed hereinbelow are designed around the cartridge design and can be fitted to the gun without changing the settings of the electronics. The hammer cartridges have flanges on them that shoulder against the gun body, setting the hammer to a specific distance from the valve every time they are installed. 
   The two hammer systems used in the gun&#39;s design are very similar to each other. The first, and preferred, system uses air to push the hammer back against a spring and hold it there. When the air is released, the hammer travels forward under spring tension, hitting the valve and causing it to release air to fire the paintball. This system needs air in only one direction which in turn has several advantages over the second system of the present invention. This hammer uses less air because it needs air in only one direction. It requires fewer parts to operate, it needs only 3-way solenoid valve instead of a 4-way solenoid valve like the second system. There are fewer seals to wear and cause drag. Using a spring loaded hammer and air pressure to return the hammer to its ready to fire position allows for a much lower pneumatics pressure than if the hammer was air operated in both directions. This lower pressure required for the hammer system also lowers the pressure that the bolt uses, which in turn means that the bolt, when encountering a ball that did not load completely, will stop against the ball and not break it. This system has been tested at pressures as low as 30 psi, at which point the gun still functioned properly. This hammer design is very simple and rugged. It retains the slidable front u-cup. This hammer system uses a spring loaded piston and air on one side to draw a vacuum on the opposite side. In the current version, this hammer does draw a vacuum but is not harnessed to do work, but instead, opens the valve to fire the paintball. This hammer version uses less air than the other version and gives better consistency during high rates of fire. 
   The second system is an air-operated spring assist hammer system. This systems works well but requires more parts and more air. The second hammer design also uses air to operate the hammer; but in both directions this time. It provides a stronger striking force by adding spring tension behind the hammer. This air-operated spring assist hammer system provides a stronger force to open valves that require a stronger opening force, due to the pressure behind the valve because of a larger surface area of the valve. This hammer will use more air than the first hammer, due to the use of air on both sides of the hammer. This hammer retains the slidable front u-cup. 
   The pneumatic cylinder used to actuate the bolt back and forth, commonly called a ram in paintball, has been simplified. The ram&#39;s outer housing is referred to as the ram tube. On the end oft he ram&#39;s shaft is a part called an h-tube. The bolt&#39;s retention pin locks into the h-tube so the ram can push the bolt back and forth as the gun is actuated. The two solenoids used to actuate the gun are off-the-shelf valves with a modification so they work wit this paintball gun. Most electronic guns use standard off the shelf valves but then build complicated manifolds or use small air lines to run the air to the places it is needed. The solenoid valves chosen for the preferred embodiment gun require only a small modification to the valve body and they fit in the best position under the gun, inside a cavity in the body. That position on the body works best as they actuate each system without having complex manifolds to direct the air to other locations. They sit directly under each component they are meant to actuate. The valves themselves lie flat against the gun body located on raised bosses milled into the body, which reduces the overall height of the gun. This position is also directly over the grip frame, keeping the paintball gun&#39;s weight centered over the hand and not unbalancing the gun. Regulated air is supplied to the two solenoid valves through an air passageway which runs down the middle of the gun between the two lower bores of the gun. The air passage is connected to the pneumatic reservoir by a cross drilled air passage into the side of the gun. Most prior art guns have to run external air lines which are easily damaged or torn off completely, to achieve the same thing. 
   The bolt used in the present paintball gun is a very distinct design over that of the bolt used on all prior art guns. All prior art bolts have an inlet hole that is positioned 90 degrees with respect to the outlet hole. They also try to squeeze the air through multiple small holes or release it through one big straight hole to make the bolt more effective. All of this only reduces the effectiveness of the bolt. The new bolt of the present invention has an inlet hole slanted 30 degrees to the outlet hole. The slant of the inlet hole reduces the amount of energy the air looses as it changes direction. The transition between the two holes is curved to allow smooth air flow between the inlet and outlet holes. The outlet hole on this bolt is also a cone shape. The cone shape keeps the air contained and focuses the air forward. The air expands evenly along the cone shape. The prior art bolts allow the air to expand all at once and exit the bolt as one solid slug of air. The present bolt design when used in the same gun as the prior art bolts, increases the velocity 30 to 70 fps higher than the prior art bolt. 
   The bolt is held in the gun by a new retaining system. Most bolts are held in the gun by simple pins that wear into the parts being held, necessitating the replacement of those parts on a routine basis. The system used in the present paintball gun allows for very quick removal and installation of the bolt for cleaning purposes. It also does not wear out the parts it is attached to. 
   The bolt retention system keeps the bolt located in the h-tube on the end of the ram but still allows the bolt to be removed quickly and easily. The bolt retention pin is located near the back of the bolt. It has a groove milled in it with a divot at each end of the groove. A ball bearing rides in the groove held in place by a spring. The ball bearing can only move between the two divots in the groove. A “stop” in the form of a turned down nose of a set screw keeps the ball bearing from backing out of the groove. This system allows the pin to be pulled up, but not out of the bolt. Then the bolt and pin can be slid out the back of the gun as one unit. This permits easy cleaning without having to keep track of a separate pin and bolt as in prior art paintball guns. Installing the bolt is the reverse of removal. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1   a  is a left side view of a preferred embodiment gun of the present invention in the ready to fire position. 
       FIG. 1   b  is a left side view of the gun of  FIG. 1   a  with hammer fired, valve open releasing air to propel the paintball. 
       FIG. 1   c  is a left side view of the gun of  FIGS. 1   a-b  with hammer returned to ready to fire position. 
       FIG. 1   d  is a right side view of the gun of  FIGS. 1   a-c  with bolt open to allow a ball to drop in. 
       FIG. 1   e  is a right side view of the gun of  FIGS. 1   a-d  with bolt closed and with ball in chamber ready to fire again. 
       FIG. 2   a  is a front end view of a preferred embodiment gun body of the present invention and the relationship of the three chambers A, B and C to each other. 
       FIG. 2   b  is a back end view of a preferred embodiment gun body of the present invention and the relationship of the three chambers A, B, and C to each other. 
       FIG. 3  is an upper schematic view of a preferred embodiment of the present invention, with parts laid out flat to show their relationship to other components in the gun and to the three chambers A, B, and C. 
       FIG. 4  is a cut away view of a preferred embodiment pneumatics pressure regulator and pneumatics air reservoir of the present invention. 
       FIG. 5  is a side cross-sectional view of a preferred embodiment ram system of the present invention. 
       FIG. 6   a  is a cut away view of a first embodiment hammer of the present invention. 
       FIG. 6   b  is a cut away view of a second embodiment hammer of the present invention. 
       FIG. 7  is a cut away view of a preferred embodiment low pressure valve of the present invention. 
       FIG. 8   a  is a cut away view of a first embodiment chamber A endcap of the present invention. 
       FIG. 8   b  is a cut away view of a second embodiment chamber A endcap of the present invention. 
       FIG. 9   a  is a cut away view of a prior art bolt. 
       FIG. 9   b  is a cut away view of a preferred embodiment enhanced flow bolt and bolt retention system of the present invention, and a cutaway of a prior art bolt for comparison. 
       FIG. 10  is a bottom view of a preferred embodiment gun body of the present invention, showing locations of the vertical mount, solenoid valves, solenoid valve air passageway and the on-off switch. 
   

   REFERENCE NUMBERS IN DRAWING 
   
       
       P Paintball 
         11  Paintball gun 
         12  grip frame 
         13  barrel 
         14  trigger 
         15  Main pressure regulator 
         16  vertical mount 
         17  receiver (gun body) 
         18  Threaded mounting for pneumatics regulator 
         19  Threaded mounting for pneumatic hammer 
         20  Threaded mounting for valve chamber endcap 
         21  o-ring, large 
         22  o-ring, small 
         23  u-cup. large (hammer &amp; ram) 
         24  u-cup, small (front of hammer) 
         25  Pneumatics regulator 
         26  Pneumatics regulator body section and low pressure reservoir side 
         27  Regulator adjusting screw 
         28  Regulator seat 
         29  Regulator disk 
         30  Regulator o-ring 
         31  Regulator piston 
         32  Regulator piston spring 
         33  Regulator piston o-ring 
         34  Ram tube 
         35  ram endcap 
         36  ram rod 
         37  ram plate 
         38  Ram tube holding pin and pneumatics reg. vent hole. 
         39  h-tube 
         40  Chamber B endcap (bolt end) 
         41  Hammer-1 
         42  Hammer-2 
         43  Hammer tube- 1   
         44  Hammer tube- 2   
         45  hammer tube endcap 
         46  hammer plate 
         47  hammer bumper 
         48  hammer weight 
         49  hammer spring- 1   
         50  hammer spring- 2   
         51  hammer chamber vent hole 
         52  Valve Body 
         53  Valve body set screw 
         54  valve spring 
         55  Valve Stem with Seal 
         56  Valve chamber 
         57  Valve chamber A endcap 
         58  chamber cap screw 
         59  low pressure chamber 
         60  Bolt 
         61  slanted inlet hole 
         62  curved transition 
         63  conical outlet hole 
         64  bolt pin and knob 
         65  ball bearing 
         66  spring 
         67  modified set screw 
         68  Air passage 
         69  4-way Solenoid 
         70  3-way Solenoid 
         71  Electronic control circuit 
         72  Battery 
         73  Micro-switch 
         75  On-off switch 
         76  Grip frame cover plate 
         77  Threaded grip frame mounting hole 
         78  Pneumatics regulator endcap 
         79  High pressure channels 
         80  Low pressure channel 
         81  Ram rod channel 
         82  Front hammer air channel 
         83  Back hammer air channel 
         84  Air reservoir 
         85  Bottom air passage 
         86  Front air outlet 
         87  Bolt retention pin distal end 
         88  Bolt retention pin proximal end 
         89  Bolt retention pin groove 
         90  Bolt retention pin divot 
         91  Ram undercut surface 
         92  Regulator vent hole 
         93  Snap ring 
         94  Reservoir chamber 
         95  Ram tube end plug 
         96  Hammer vent hole 
     
  
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, and alterations and modifications in the illustrated device, and further applications of the principles of the invention as illustrated therein are herein contemplated as would normally occur to one skilled in the art to which the invention relates. 
   With reference to  FIGS. 1   a-e,  there are shown left and right side elevational views of a preferred embodiment electronic paintball gun of the present invention, indicated generally at  11 . Front and rear end elevational views of the paintball gun  11  are illustrated in  FIGS. 2   a-b,  respectively. The paintball gun  11  includes a gun body  17 , preferably formed from extruded aluminum (but which may be formed from any suitable material), which include three chambers A, B and C formed axially parallel to one another and arranged such that lines drawn connecting the axis of each of the three chambers in a plane perpendicularly intersecting the three axes form a triangle, and preferably an equilateral triangle. Arrangement of the three chambers in this manner provides significant performance benefits to the various gun functions, as described in greater detail hereinbelow. 
   The preferred embodiment electronic paintball gun  11  includes a grip frame  12  mounted to the body  17 , the grip frame  12  including a trigger  14 . The grip frame  12  is adapted to be easily gripped by a human hand, such that the index finger rests upon the trigger  14 . The grip frame  12  attaches to the body  17  by means of any convenient attachment mechanism, such as bolts engaging the threaded bolt holes  77 . The body  17  further includes a barrel  13  through which a paintball P is ejected when the gun  11  is fired. The paintballs P enter the gun body  17  through a paintball hopper feed tube H. The body  17  further includes a vertical mount  16  machined therein, and adapted to receive a main pressure regulator  15 . A supply of compressed gas (not shown) is attached to the main pressure regulator  15 , which regulates the pressure of this gas to a predetermined level (preferably approximately 180 psi). Compressed gas exiting the main pressure regulator  15  flows up through the vertical mount  16 , filling the valve chamber  56  and the high pressure side of the pneumatics regulator  25 . 
   Chamber A carries the hammer  41  and low pressure chamber  59 . Chamber B carries the pneumatics regulator  25  and the ram tube  34 . The chamber C carries the bolt  60 . 
   Referring now  FIG. 3 , the electronic paintball gun  11  of the present invention is illustrated schematically with all three chambers A, B and C laid side-by-side for ease of illustration and discussion. As noted hereinabove, the preferred embodiment of the electronic paintball gun  11  arranges the chambers A, B and C in a triangular relationship. 
   At the front end of the gun, a pneumatics pressure regulator  25  screws into the chamber B by means of interengaging threads  18  or other convenient attachment means. The pneumatic regulator  25  is shown apart from the gun  11  in FIG.  4 . As with each of the subsystems of the electronic paintball gun  11 , the pneumatics regulator  25  is formed as a self-contained module which may be screwed into one of the exposed ends of the chambers A, B and C, thereby allowing for simplified replacement in the field. The pneumatics regulator  25  includes an endcap  78 . The pneumatics regulator  25  may be threaded into the chamber B by gripping the endcap  78 . The endcap  78  forms the high pressure side of the pneumatics regulator  25 , while an attached body section  26  forms the low pressure side of the pneumatics regulator  25 . 
   As best shown in  FIGS. 1   d  and  4 , high pressure air from the vertical mount  16  enters the high pressure side of the pneumatics regulator  25  through channels  79  formed in the endcap  78 . By use of an o-ring  21  to seal the end of the chamber B, high pressure air can be stored within the endcap  78 . A regulator adjusting screw  27  and regulator seat  28  fit within the high pressure cavity formed inside the endcap  78 . A cavity  79  is provided so that an Allen wrench may be used to adjust the position of the adjusting screw  27  with respect to the endcap  78 . The regulator body  25  compresses a regulator disk  29  and regulator o-ring  30  as the body  25  is tightened onto the regulator body  26 . Regulator piston  31 , regulator piston spring  32  and regulator piston o-ring  33  are held within regulator body  26  by a snap ring  93 . 
   The high pressure air entering through the channels  79  flows through the center of regulator piston  31  and builds up pressure within chamber  94 . This pressure acts upon regulator piston  31 , pushing it to the left (and thereby compressing regulator piston spring  32 ) until the piston  31  seats against regulator seat  28  on adjusting screw  27 . This prevents further air flow through the center of regulator piston  31  until the pressure in chamber  94  is released, allowing spring  32  to push piston  31  off to the seat  28 . This creates a regulated supply of air within the chamber  94  of (preferably) 80 psi. It will be appreciated by those skilled in the art that adjustment of the seat  28  position by turning the screw  27  will allow any desired air pressure to be achieved. 
   This low pressure air supply is used for the other pneumatics systems of the electronic paintball gun  11 . The low pressure regulated air exits the pneumatics regulator  25  by means of the low pressure channel  80  (see FIG.  3 ). 
   With reference now to  FIGS. 3 and 5 , the remainder of the chamber B is filled with the pneumatic ram, consisting of the ram tube  34 , and the ram endcap  35  which preferably screws into the ram tube  34 . The pneumatic ram slides back and forth within the space of chamber B during operation of the gun  11 . The end of chamber B is sealed with chamber B endcap  40 , which also preferably threadingly engages chamber B. 
   The ram endcap  35  holes a u-cup  23  and ram plate  37  in place inside the ram tube  34 . A ram rod  36  slides back and forth through the center of the ram tube  34 . The ram rod  36  also has two u-cups  23  on one end, facing back to back, to provide a seal between the two sides of the pneumatic cylinder thereby formed with the ram tube  34 . The ram tube  34  is held in place within the gun body  17  by means of a ram tube end plug  95  and a retaining pin  38 , which also acts as the vent hole for the pneumatic regulator  25 . 
   The ram rod  36  is threadingly engaged to an h-tube  39 . As discussed in greater detail hereinbelow, the h-tube  39  pulls the bold  60  back and forth during cycling of the gun  11  by use of the bolt retention pin  64  (see FIG.  9 B). Air enters the left side of the ram rod  36  through undercut surfaces  91  and channels  81 . The undercut surfaces  91  are formed around the outside of ram tube  34  and line up with air passages from the solenoid valve  69  (see FIG.  10 ). The air pressure acting upon the end of the ram rod  36  causes the ram rod  36  to slide upon u-cups  23  within the ram rod  34 . This motion causes the h-tube  39  to move back and forth within the chamber B. O-rings  22  act as bumpers to keep the ram rod  36  from damaging the other components by preventing metal-to-metal contact. 
   With reference now to  FIGS. 3 and 6   a,  the pneumatic hammer  41  slides within a hammer tube  43  and a hammer tube endcap  45  which is preferably threadingly engaged with the hammer tube  43 , which is in turn preferably threadingly engaged (by means of threads  19 ) to chamber A with o-ring  21  therebetween. The hammer  41  incorporates a sliding front u-cup  24  and rear u-cup  23 , allowing the hammer  41  to slide within the hammer tube endcap  45  and hammer tube  43 , respectively. The hammer tube  43  also houses a hammer plate  46 , a hammer bumper  47  (preferably made from rubber, urethane or soft plastic), a hammer spring  49  and a hammer weight  48 , which provides a surface upon which the hammer spring  49  pushes. 
   When the hammer  41  is at rest, air from solenoid  70  (as discussed hereinbelow) enters air passage  82  and pushes the hammer  41  and hammer weight  48  back against the hammer bumper  47 , compressing the hammer spring  49  (see FIG.  3 ). When solenoid  70  is turned on, it releases the air from the front side of the hammer  41 , causing the compressed hammer spring  49  to throw the hammer  41  forward. Forward movement of the hammer  41  pulls a vacuum on the back side of the hammer  41 , which is vented by the vent hole  96 . The hammer  41  stops against the hammer plate  46 , which is held in place by the hammer tube endcap  45  screwed into the hammer tube  43 . The sudden stopping of the hammer  41  against the hammer plate  46  transfers all of the forward momentum of the hammer  41  to the valve stem  55  of the valve body  52  (see FIG.  3 ). This opens the valve stem  55 , once again supplying air to the front of the hammer  41 , moving it back against the hammer bumper  47  and recompressing the hammer spring  49 . 
   The use of the sliding front u-cup  24  reduces the sliding friction below that achieved by the use of a stationary seal, as in prior art designs. The prior art stationary seal requires a highly polished and smoothed surface on the hammer. Use of the sliding u-cup  24  removes the need for polishing and grinding the shaft of the hammer as is done on all prior art pneumatic hammer systems, thereby simplifying the construction of the hammer  41  of the present invention. 
   Referring now to  FIG. 6   b,  a second embodiment pneumatic hammer of the present invention is illustrated. The second embodiment pneumatic hammer includes a hammer  42  that utilizes two u-cups  23  to seal both ends of the hammer  42 . The hammer  42  is housed in hammer tube  44 , which also houses the hammer plate  46 , the hammer bumper  47  and the hammer spring  50 . When the hammer  42  is at rest, air from the solenoid  70  enters the air passage  92  and pushes the hammer  42  and the hammer weight  48  back against the hammer bumper  47 , thereby compressing the hammer spring  50 . When the solenoid  70  is turned on, it releases air from the front side of the hammer  42  through the front hammer air channel  82 , and supplies air to the back side of the hammer  42  through back hammer air channel  83  at the same time that the hammer spring  50  throws the hammer  42  forward. The hammer  42  stops against the hammer plate  46 , which is held in place by the hammer tube endcap  45  preferably screwed into the hammer tube  44 . This sudden stop of the hammer  42  transfers all of the forward momentum to the valve  52 , thereby opening it. The solenoid  70  then releases air from the back side of the hammer  42  and again supplies air to the front side of the hammer  42 , thereby moving the hammer  42  back against the hammer spring  50 . As discussed hereinabove with respect to  FIG. 6   a,  with use of the sliding u-cup  24  provides significant advantages over the stationary seal design used in prior art pneumatic hammers. 
   Referring now to  FIG. 7 , there is illustrated a valve body  52  having a moveable valve stem  55  therein. The valve stem  55  is actuated by the pneumatic hammer, as described in more detail hereinabove. The valve  52 ,  55  is of the type described in U.S. Pat. No. 5,791,328, the specification and drawings of which are incorporated herein by reference in their entirety. As shown in  FIG. 3 , the valve body  52  is held in place within the chamber A by means of a valve body set screw  53 , which penetrates the gun body  17 . Excess air between the valve body  52  and the hammer endcap  45  is vented through vent hole  51 . O-ring seals  21  seal the valve body  52  against the sides of the chamber A. 
   With reference to  FIGS. 3 and 8   a,  the other end of chamber A is sealed by a valve chamber endcap  57  which preferably threadingly engages the chamber A by means of threaded surface  20 . An o-ring  21  provides an air-tight seal. The endcap  57  preferably includes a recess  58  to allow the use of an Allen wrench to tighten the endcap  57 . 
   The endcap  57  seals the valve chamber  56  and holds a valve spring  54  in place against the valve stem  55 , thereby sealing off air from escaping through the valve body  52  until the hammer  41  strikes the valve stem  55 . 
   An alternative for the endcap  57  is the valve chamber endcap  59  illustrated in  FIG. 8   b.  The valve chamber endcap  59  includes an extended air reservoir  84 , allowing the gun  11  to store a larger volume of low pressure air and thus allowing the paintball gun  11  to shoot a paintball P at the normal velocity of 300 fps, but at a lower pressure than with the endcap  57 . The use of a low pressure chamber in this fashion is explained in greater detail in U.S. Pat. No. 5,904,133, the drawings and specifications of which are incorporated herein by reference in their entirety. 
   Referring now to  FIG. 9   a,  there is illustrated a bolt from a prior art pneumatic paintball gun. Because air enters the bolt through a side passage  85  and exits the bolts through a front air outlet  86 , the air is forced to execute a 90 degree turn therebetween, thereby causing turbulent flow of the air and greatly decreasing the power of the air charge. 
   In contrast, a bolt  60  of the present invention is illustrated in  FIG. 9   b.  The bolt  60  uses a new airflow channel shape which increases performance over the prior art bolt illustrated in  FIG. 9   a.  The bolt  60  has a slanted inlet hole  61  preferably tilted at an angle of between 15 and 45 degrees, and more preferably at an angle of 30 degrees with respect to a plane transverse to the longitudinal axis of the bolt  60 . The bolt  60  further includes a generally conically shaped outlet path  63 . A radiused section  62  provides a transition between the slanted inlet  61  and the conical outlet  63 . Provision of the slanted inlet  61  helps the air transition through its approximately 60 degree change of direction with less turbulence and therefore with less loss of energy. The conical outlet  63  keeps the air contained and focuses the air forward to expand evenly in a cone shape instead of allowing the air to expand all at once as it exits the bolt, as in prior art bolts. 
   With reference to  FIGS. 3 and 9   b,  the bolt  60  resides within the chamber C of the gun  11 . The bolt  60  includes a bolt retention pin  64  extending therethrough, wherein a distal end  87  of the bolt retention pin  64  extends through a groove (not shown) joining the chambers B and C, such that the distal end  87  is captured by the h-tube  39  of the pneumatic ram. This causes the bolt  60  to reciprocate within chamber C in unison with the reciprocation of the ram rod  36  and h-tube  39  within chamber B. The bolt retention pin  64  proximal end  88  extends through a groove (not shown) formed in the chamber C, thereby allowing it to protrude from the exterior of the gun body  17 . By grasping the proximal end  88  and pulling the retention pin  64  away from the gun body  17 , the distal end  87  of the retention pin  64  may be disengaged from the h-tube  39 , thereby allowing the bolt  60  to be freely slid out of the back end of chamber C. This allows the bolt to be removed quickly and easily. The retention pin  64  has a groove  89  built into it with a divot  90  at each end of the groove  89 . A ball bearing  65  rides in the groove  89  and is held in place by the force of a spring  66 . The ball bearing  65  can only move between the two divots  90  in the groove  89 . A stop  67  in the form of a turned down nose of a set screw keeps the ball bearing  65  from backing out of the groove  89 . This system allows the retention pin  64  to be pulled up but not out of the bolt  60 . Pulling the retention pin  64  toward the proximal end  88  causes the ball bearing  65  to move to the second divot  90 , freeing the retention pin  64  of the h-tube  39 , allowing disassembly of the bolt from the chamber C. Installation of the bolt  60  back into the gun  11  follows the reverse procedure. 
   With reference to  FIGS. 1   a-e  and  10 , the solenoid system of the paintball gun  11  of the present invention is illustrated. Regulated air from the pneumatic regulator  25  flows through air passages  80  and  68  inside the bottom of the gun body  17  to the electronic solenoids  69  and  70 . Air passages  68  and  80  are coupled by a tube (not shown) exterior of the gun body  17 . Electronic solenoids  69  and  70  are 4-way valves manufactured by MAC Valves in Michigan. They are a low voltage, low wattage valve. The model number is 44B-AAA-GDSA-1BA with a special modification. The air ports are normally located on the sides of the valve with one input port, 2 output ports and 2 exhaust ports. The valves were modified by adding 1 new inlet and 2 new outlet ports to the large flat surfaces of the valve body (see FIG.  10 ). The existing inlet and output ports are plugged with set screws while the exhaust ports are left open to allow the valve to vent the air. The solenoids  69 ,  70  direct regulated air to the pneumatic ram, pulling the bolt  60  forward and sending air to the hammer system, pushing the hammer  41  back to the ready-to-fire position. The gun  11  includes and an on-off switch  75  that allows the user of the gun  11  to turn the game  11  off in order to extend the battery  72  life. The batteries  72  are preferably housed within the grip frame  12 . The grip frame cover plate  76  covers the two solenoid valves  69 ,  70  and forms a storage compartment  76  for the electronic circuit board  71  that controls the guns functions. 
   Referring once again to  FIGS. 1   a  and  3 , the paintball gun  11  is shown with all components at rest and in the ready-to-fire position. At rest, air pressure pushes the hammer  41  back, compressing the hammer spring  49  inside the hammer tube  43 , which is housed inside chamber A of the main gun body  17 . In chamber B, air pressure pushes the ram  36  forward, keeping the bolt  60  forward. This keeps the paintball P in chamber C. Air pressure also pushes the regulator plunger  28  against the regulator set  29 , sealing the high pressure air from the low pressure side  33  of the regulator. Air pressure also keeps the valve stem  55  sealed against the valve body  52 , thereby keeping the air inside the valve chamber  56 . 
   With reference to  FIGS. 1   b  and  3 , when the trigger  14  is pulled and activates the microswitch  73 , the electronic control circuit  71  activates solenoid  70 , releasing the air from the front of the hammer  41 , thereby allowing spring  49  to push the hammer  41  at a high speed. Hammer  41  hits the valve stem  55 , opening the valve  52  and releasing air from the valve chamber  56  into the slanted inlet hole  61  of the bolt  60 . As the air exits the conical outlet hole  63 , the paintball P is pushed down the barrel  13 . 
   With reference to  FIGS. 1   c  and  3 , the circuit board  71  keeps the solenoid  70  turned on for a predetermined amount of time, then turns the solenoid  70  off. This returns the air to the front of the hammer  41 , pushing the hammer to its ready-to-fire position compressing hammer spring  49 . 
   With reference to  FIGS. 1   d  and  3 , at a predetermined time interval after hammer solenoid  70  is turned off, the electronic circuit board  71  turns on the bolt solenoid  69 . Turning on the bolt solenoid  69  releases air from behind the ram  36  and supplies air to the front side of the ram  36 . This in turn pushes the ram  36  backwards, pulling the bolt  60  back to its rearward position. This allows another paintball P to drop into the chamber C. The electronic circuit board  71  waits a predetermined amount of time so that the paintball P can drop into the breach and then turns off the solenoid  69 , storing energy from the solenoid  69  on the circuit board  71  and allowing the air to vent out of the front side of the ram  36  and returning air to the back side of the ram  36 . This air pushes the ram  36  back to its rest position, which in turn pulls bolt  60  forward to close the breach, thereby sealing the paintball P inside chamber C. In  FIG. 1   e,  the paintball gun  11  has returned to the ready-to-fire state of  FIG. 1   a.    
   While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.