Abstract:
A compressed gas powered projectile accelerator employing “dynamic-regulation” as herein defined; having, in a simple-to-manufacture, easy-to-maintain, durable preferred embodiment; either a slider, reciprocally moveable within a passage, being releasable by the action of a sear and trigger from a cocked position, controlling flow of compressed gas into a breech; or an electric valve performing the same function under the control of an electronic circuit and trigger; and a spring-biased slider, reciprocally moving within said breech and a barrel, controlling the flow of projectiles and compressed gas into said barrel. Said compressed gas-powered projectile accelerator circumvents many of the problems associated with projectile accelerators known to be in the art, capable of reliable semi-automatic and fully-automatic operation using carbon dioxide liquid/gas mixtures.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates, in general, to compressed gas-powered projectile accelerators, generally known as “air-guns”, irrespective of the type of the projectile, gas employed, scale, or purpose of the device.  
           [0003]    2. Description of the Prior Art  
           [0004]    Compressed gas-powered projectile accelerators have been used extensively to propel a wide variety of projectiles. Typical applications include weaponry, hunting, target shooting, and recreational (non-lethal) combat. In recent years, a large degree of development and invention has centered around recreational combat, where air-guns are employed to launch non-lethal projectiles which simply mark, rather than significantly injure or damage the target. Between launching projectiles such air-guns are generally loaded and reset to fire when the trigger is pulled, generally referred to as “re-cocking” either by an additional manual action by the operator, or pneumatically, as part of each projectile-accelerating event or “cycle”. These devices may be divided into two categories—those that are “non-regulated” or “inertially-regulated”, and those that are “statically-regulated”.  
           [0005]    Non-regulated or inertially-regulated air-guns direct gas from a single storage reservoir, or set of reservoirs that are continuously connected without provision to maintain a static (zero-gas flow) pressure differential between them, to accelerate a projectile through and out of a tube or “barrel”. The projectile velocity is typically controlled by mechanically or pneumatically controlling the open time of a valve isolating the source gas, which is determined by the inertia and typically spring force exerted on moving parts. Examples of manually re-cocked non-regulated or inertially-regulated projectile accelerators are the inventions of Perrone, U.S. Pat. No. 5,078,118; and Tippmann, U.S. Pat. No. 5,383,442. Examples of pneumatically re-cocked non-regulated or inertially-regulated projectile accelerators (this type of projectile accelerator being the most commonly used in recreational combat) are the inventions of Tippman, U.S. Pat. No. 4,819,609; Sullivan, U.S. Pat. No. 5,257,614; Perrone, U.S. Pat. Nos. 5,349,939 and 5,634,456; and Dobbins et al., U.S. Pat. No. 5,497,758.  
           [0006]    Statically-regulated air-guns transfer gas from a storage reservoir to an intermediate reservoir, through a valve which regulates pressure within the intermediate reservoir to a controlled design level, or “set pressure”, providing sufficient gas remains within the storage reservoir with pressure in excess of the intermediate reservoir set pressure. This type of air-gun directs the controlled quantity of gas within said intermediate reservoir in such a way as to accelerate a projectile through and out of a barrel. Thus, for purposes of discussion, the operating sequence or “projectile accelerating cycle” or “cycle” can be divided into a first step where said intermediate reservoir automatically fills to the set pressure, and a second step, initiated by the operator, where the gas from said intermediate reservoir is directed to accelerate a projectile. The projectile velocity is typically controlled by controlling the intermediate reservoir set pressure. Examples of statically regulated projectile accelerators are the inventions of Milliman, U.S. Pat. No. 4,616,622; Kotsiopoulos, U.S. Pat. No. 5,280,778; and Lukas et al., U.S. Pat. No. 5,613,483.  
           [0007]    More recently, electronics have been employed in both non-regulated and statically-regulated air-guns to control actuation, timing and projectile velocity. Examples of electronic projectile accelerators are the inventions of Rice et al., U.S. Pat. No. 6,003,504; and Lotuaco, III, U.S. Pat. No. 6,065,460.  
           [0008]    Problems with compressed gas powered guns known to be in the art, relating to maintenance, complexity, and reliability, are illustrated by the following partial list:  
           [0009]    1. Sensitivity to liquid CO 2 —The most common gas employed by air-guns is CO 2 , which is typically stored in a mixed gas/liquid state. However, inadvertent feed of liquid CO 2  into the air-gun commonly causes malfunction in both non-regulated or intertially regulated air-guns and, particularly, statically-regulated air-guns, due to adverse effects of liquid CO 2  on valve and regulator seat materials. Cold weather exacerbates this problem, in that the saturated vapor pressure of CO 2  is lower at reduced temperatures, necessitating higher gas volume flows. Additionally, the dependency of the saturated vapor pressure of CO 2  on temperature results in the need for non-regulated or inertially regulated air-guns to be adjusted to compensate for changes in the temperature of the source gas, which would otherwise alter the velocity to which projectiles are accelerated.  
           [0010]    2. Difficultly of disassembly—In many air-guns known to be in the art, interaction of the bolt with other mechanical components of the device complicates removal of the bolt, which is commonly required as part of cleaning and routine maintenance.  
           [0011]    3. Double feeding—air-guns known to be in the art typically hold a projectile at the rear of the barrel between projectile accelerating cycles. In cases where the projectile is round, a special provision is required to prevent the projectile from prematurely rolling down the barrel. Typically, a lightly spring biased retention device is situated so as to obstruct passage of the projectile unless the projectile is thrust with enough force to overcome the spring bias and push the retention device out of the path of the projectile for sufficient duration for the projectile to pass. Alternatively, in some cases close tolerance fits between the projectile caliber and barrel bore are employed to frictionally prevent premature forward motion of the projectile. However, rapid acceleration of the air-gun associated with movement of the operator is often of sufficient force to overcome the spring bias of retention device, allowing the projectile to move forward, in turn allowing a second projectile to enter the barrel. When the air-gun is subsequently operated, either both projectiles are accelerated, but to lower velocity than would be for a single projectile, or, for fragile projectiles, one or both of the projectiles will fracture within the barrel.  
           [0012]    4. Bleed up of pressure—Statically-regulated air-guns require a regulated seal between the source reservoir and intermediate reservoir which closes communication of gas between said reservoirs when the set pressure is reached. Because this typically leads to small closing force margins on the sealing surface, said seal commonly slowly leaks, causing the pressure within the intermediate reservoir to slowly increase or “bleed up” beyond the intended set pressure. When the air-gun is actuated, this causes the projectile to be accelerated to higher than the intended speed, which, with respect to recreational combat, endangers players.  
           [0013]    5. Not practical for fully-automatic operation—Air-guns which have an automatic re-cock mechanism can potentially be designed so as accelerate a single projectile per actuation of the trigger, known as “semi-automatic” operation, or so that multiple projectiles are fired in succession when the trigger is actuated, known as “fully-automatic” operation. (Typically air-guns that are designed for fully-automatic operation are designed such that semi-automatic operation is also possible.) Most air-guns known to be in the art are conceptually unsuitable for fully-automatic operation in that there is no automated provision for the timing between cycles required for the feed of a new projectile into the barrel, this function being dependent upon the inability of the operator to actuate the trigger in excess of the rate at which new projectiles enter the barrel when operated semi-automatically. Air-guns known to be in the art which are capable of fully-automatic operation typically accommodate this timing either by inertial means, using the mass-induced resistance to motion of moving components, or by electronic means, where timing is accomplished by electric actuators operated by a control circuit, both methods adding considerable complexity.  
           [0014]    6. Difficult manufacturability—Many air-guns known to be in the art, particularly those designed for fully automatic operation, are complex, requiring a large number of parts and typically the addition of electronic components.  
           [0015]    7. Stiff or operator sensitive trigger pull—The trigger action of many non-electronic air-guns known to be in the art initiates the projectile accelerating cycle by releasing a latch obstructing the motion of a spring biased component. In many cases, since the spring bias must be quite strong to properly govern the projectile acceleration, the friction associated with the release of this latch results in an undesirably stiff trigger action. Additionally, this high friction contact results in wear of rubbing surfaces. Alternatively, in some cases, to reduce mechanical complexity and circumvent this problem, the trigger is designed such that its correct function is dependent upon the technique applied by the operator, resulting in malfunction if the operator only partially pulls the trigger through a minimum stroke.  
           [0016]    8. High wear on striking parts—In many air-guns known to be in the art, particularly those designed for semi-automatic or fully-automatic operation, the travel of some of the moving parts is limited by relatively hard impact with a bumper. Additionally, in many cases, a valve is actuated by relatively hard impact from a slider. The components into which the impact energy is dissipated exhibit increased rates of wear. Further, wear of high impact surfaces in the conceptual design of many air-guns known to be in the art make them particularly un-adaptable to fully-automatic operation.  
           [0017]    9. Contamination—Many of the air-guns known to be in the art require a perforation in the housing to accommodate the attachment of a lever or knob to allow the operator to perform a necessary manipulation of the internal components into a ready-to-fire configuration, generally known as “cocking”. This perforation represents an entry point for dust, debris, and other contamination, which may interfere with operation.  
         BRIEF SUMMARY OF THE INVENTION  
         [0018]    While some compressed gas-powered projectile accelerators known to be in the art circumvent some of the above listed problems, all of these and other problems are mitigated or eliminated by the compressed gas-powered projectile accelerator of the present invention. Said compressed gas-powered projectile accelerator employs a “dynamically-regulated” cycle to avoid the problems associated with both non-regulated or inertially regulated air-guns and statically-regulated air-guns.  
           [0019]    The term “dynamically-regulated” refers to the fact that the compressed gas-powered projectile accelerator of the present invention, in contrast to air-guns known to be in the art, fills an intermediate reservoir as an integral part of, and at the beginning of, each projectile accelerating cycle. The cycle is initiated by the operator, preferably by the action of a trigger, which causes the filling of the intermediate reservoir by compressed gas. The second step of the cycle where the projectile is accelerated is then automatically activated when the pressure reaches a design threshold. In so doing, the filling of the intermediate reservoir may be used not only to regulate the projectile velocity, but the time of each cycle, making fully automatic operation possible without necessity for inertial or electronic timing. Additionally, since the gas in the intermediate reservoir is used as soon as the pressure reaches the set pressure, the problem of potential bleed-up of the pressure in the intermediate reservoir is eliminated. For further illustration, the type of regulation employed by the compressed gas-powered projectile accelerator of the present invention may be contrasted with that employed by statically-regulated air-guns known to be in the art, where the intermediate reservoir is automatically filled to the set pressure, and the gas stored until the projectile accelerating step of the cycle is triggered by the operator.  
           [0020]    This unique cycle additionally maximizes reliability and minimizes wear by allowing all sliding components to rotate freely and requiring no hard impact or high pressure sliding contact between components. The simplicity of assembly allows the housing of the compressed gas-powered projectile accelerator of the present invention to be made as a single piece and the few moving parts can be easily removed for inspection and cleaning.  
           [0021]    Additional understanding of these and other advantages of the compressed gas-powered projectile accelerator of the present invention can be found in the subsequent, detailed description taken in conjunction with the accompanying drawings forming a part of this specification. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0022]    [0022]FIG. 1 is a view from the side of a compressed gas-powered projectile accelerator made according to the present invention.  
         [0023]    [0023]FIG. 2 is a view from the rear of a compressed gas-powered projectile accelerator made according to the present invention.  
         [0024]    [0024]FIG. 3 is a sectional view from the front of a compressed gas-powered projectile accelerator made according to the present invention.  
         [0025]    [0025]FIG. 4 is a sectional view from the side of a compressed gas-powered projectile accelerator made according to the present invention with internal components removed to show internal cavities and passages.  
         [0026]    [0026]FIG. 5 is a sectional view from the side of upper rear portion of a compressed gas-powered projectile accelerator made according to the present invention shown to advantage, with internal components removed to show internal cavities and passages.  
         [0027]    [0027]FIG. 6 is a sectional view from the side of upper rear portion of a compressed gas-powered projectile accelerator made according to the present invention shown to advantage where test/bleed ports have been eliminated by welding and strategic orientation of the rear passage, with internal components removed to show internal cavities and passages.  
         [0028]    [0028]FIG. 7 is a sectional view from the side of upper rear portion of a compressed gas-powered projectile accelerator made according to the present invention shown to advantage where the bolt rest-point passage and rear passage have been replaced by a slot, eliminating corresponding perforations in the upper housing, with internal components removed to show internal cavities and passages.  
         [0029]    [0029]FIG. 8 is a sectional view from the side of a compressed gas-powered projectile accelerator made according to the present invention.  
         [0030]    [0030]FIG. 9 is a sectional view from the side of the upper rear portion of a compressed gas-powered projectile accelerator made according to the present invention shown to advantage with purge holes in the spring guide.  
         [0031]    [0031]FIG. 10 is a sectional view from the side of the upper rear portion of a compressed gas-powered projectile accelerator made according to the present invention shown to advantage with a truncated spring guide eliminating need for purge holes.  
         [0032]    [0032]FIG. 11 is a sectional view from the side of the upper rear portion of a compressed gas-powered projectile accelerator made according to the present invention shown to advantage with purge holes in the spring guide and an enlarged bolt spring.  
         [0033]    [0033]FIG. 12 is a sectional view from the side of the upper rear portion of a compressed gas-powered projectile accelerator made according to the present invention shown to advantage with a truncated spring guide, an enlarged bolt spring, and purge holes in the bolt instead of the spring guide.  
         [0034]    [0034]FIG. 13 is a view from the side of the front portion of a compressed gas-powered projectile accelerator made according to the present invention shown to advantage.  
         [0035]    [0035]FIG. 14 is a view from the side of the region in the vicinity of the trigger of a compressed gas-powered projectile accelerator made according to the present invention shown to advantage.  
         [0036]    [0036]FIGS. 15A and 15B are sectional views from the rear of the region in the vicinity of the trigger of a compressed gas-powered projectile accelerator made according to the present invention showing the mode-selector cam in the semi-automatic and fully-automatic positions, respectively, with ball and spring retention assembly, shown to advantage.  
         [0037]    [0037]FIGS. 16A and 16B are sectional views of the region in the vicinity of the trigger of a compressed gas-powered projectile accelerator made according to the present invention, as viewed diagonally from the lower rear, showing the safety cam in the non-firing and firing positions, respectively, with ball and spring retention assembly, shown to advantage.  
         [0038]    FIGS.  17 A-I are sectional views from the side of a compressed gas-powered projectile accelerator made according to the present invention, illustrating semi-automatic operation.  
         [0039]    FIGS.  18 A-H are sectional views from the side of a compressed gas-powered projectile accelerator made according to the present invention, illustrating fully-automatic operation.  
         [0040]    [0040]FIG. 19 is a view from the side of the front portion of a compressed gas-powered projectile accelerator made according to the present invention with the addition of a cocking knob, shown to advantage.  
         [0041]    [0041]FIG. 20 is a sectional view from the top of the front portion of a compressed gas-powered projectile accelerator made according to the present invention with the addition of a cocking knob, shown to advantage.  
         [0042]    [0042]FIG. 21 is a view from the side of the front portion of a compressed gas-powered projectile accelerator made according to the present invention with the addition of a cocking manifold, slider, and spring assembly, shown to advantage.  
         [0043]    [0043]FIG. 22 is a sectional view from the top of the front portion of a compressed gas-powered projectile accelerator made according to the present invention with the addition of a cocking manifold, slider, and spring assembly, shown to advantage.  
         [0044]    [0044]FIG. 23 is a sectional view from the side of the region in the vicinity of the source gas passage of a compressed gas-powered projectile accelerator made according to the present invention, shown to advantage.  
         [0045]    [0045]FIG. 24 is a sectional view from the side of the region in the vicinity of the source gas passage of a compressed gas-powered projectile accelerator made according to the present invention with baffle inserts inside the source gas passage, shown to advantage.  
         [0046]    [0046]FIG. 25 is a sectional view from the side of the region in the vicinity of the source gas passage of a compressed gas-powered projectile accelerator made according to the present invention with regulator components inserted inside the source gas passage, shown to advantage.  
         [0047]    [0047]FIG. 26 is a view from the side of a compressed gas-powered projectile accelerator made according to the present invention with an pneumatically assisted feed system.  
         [0048]    [0048]FIG. 27 is a view from the rear of a compressed gas-powered projectile accelerator made according to the present invention with a pneumatically assisted feed system.  
         [0049]    [0049]FIG. 28 is a sectional view from the front of a compressed gas-powered projectile accelerator made according to the present invention with a pneumatically assisted feed system.  
         [0050]    [0050]FIG. 29 is a sectional view from the side of a compressed gas-powered projectile accelerator made according to the present invention with a pneumatically assisted feed system.  
         [0051]    [0051]FIG. 30 is a view from the rear of a compressed gas-powered projectile accelerator made according to the present invention with a variable volume chamber connected to the valve passage.  
         [0052]    [0052]FIG. 31 is a sectional view from the top of a compressed gas-powered projectile accelerator made according to the present invention with a variable volume chamber connected to the valve passage.  
         [0053]    [0053]FIG. 32 is a sectional view from the top of a compressed gas-powered projectile accelerator made according to the present invention with a variable volume chamber connected to the valve passage and with the valve slider spring replaced by a pneumatic piston.  
         [0054]    [0054]FIG. 33 is a view from the rear of an electronic compressed gas-powered projectile accelerator made according to the present invention.  
         [0055]    [0055]FIG. 34 is a sectional view from the side of an electronic compressed gas-powered projectile accelerator made according to the present invention.  
         [0056]    [0056]FIG. 35 is a view from the rear of an electronic compressed gas-powered projectile accelerator made according to the present invention with a pressure transducer connected to the rear of the valve passage.  
         [0057]    [0057]FIG. 36 is a sectional view from the side of an electronic compressed gas-powered projectile accelerator made according to the present invention with a pressure transducer connected to the rear of the valve passage. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0058]    An embodiment to be preferred of a compressed gas-powered projectile accelerator of the present invention is here and in figures disclosed. For clarity, within this document all reference to the top and bottom of the compressed gas-powered projectile accelerator will correspond to said accelerator as oriented in FIG. 1, the top of the figure when oriented such that the text is upright corresponding to top of said accelerator, and the bottom of the figure when oriented such that the text is upright corresponding to the bottom of said accelerator. Likewise, all reference to the front of said accelerator will correspond to the leftmost part of said accelerator as viewed in FIG. 1 when oriented with the text upright, and all reference to the rear of said accelerator will correspond to the rightmost part of said accelerator as viewed in FIG. 1 when oriented with the text upright. Referring to the figures, the gas-powered accelerator of the present invention includes, generally:  
         [0059]    A housing  1 , preferably made of a single piece, shown in the figures in the preferred shape of a pistol which is penetrated by hollow passages which contain the internal components.  
         [0060]    A preferably cylindrical receiver passage  2  of varying cross-section forms a breech  3  and barrel  4 , the latter being preferably extended by the addition of a tubular member, hereafter denoted the “barrel extension”  5 , which is preferably screwed into the housing  1  or otherwise removably attached. The barrel  4  is intersected by a projectile feed passage  6  into which projectiles are introduced by arbitrary means from outside the housing  1 . The projectile feed passage  6  may meet the barrel  4  at an arbitrary angle but preferably may be at least partially vertically inclined to take advantage of gravity to bias projectiles to move into the barrel  4 ; conversely an alternate bias, such as a spring mechanism may be employed. The projectile feed passage  6  can connect such that its  6  center axis intersects the center axis of the barrel  4 , or, as shown in the examples in the figures, the projectile feed passage  6  center axis can be offset from the center axis of the barrel  4 , as long as the intersection forms a hole sufficiently sized for the passage of projectiles from the projectile feed passage  6  into the barrel  4 . Also, the breech  3  diameter may optionally be slightly less than that of the barrel  4  immediately rearward of where the projectile feed passage  6  intersects the barrel  4  to help prevent projectiles from sliding or rolling rearward, as shown in FIG. 4. The examples shown in the figures are designed to introduce spherical projectiles under the action of both gravity and suction, and includes a cap  7  at the end of the projectile feed passage  6  to prevent movement of projectiles beyond the entry point into the barrel  4 . This “projectile feed passage cap”  7  can be designed to be rotatable, with a beveled surface at the point of contact with projectiles, such that in one orientation said projectile feed passage cap  7  will facilitate movement of projectiles into the barrel  4 , but, when rotated 180° will prevent movement of projectiles into the barrel  4 .  
         [0061]    Preferably parallel to the receiver passage  2  is a preferably cylindrical valve passage  8  of varying cross section which is connected to the breech  3  by a gas feed passage  9 , a bolt rest-point passage  10 , and a rear passage  11 . The valve passage  8  is intersected by a source gas passage  12  and a trigger cavity  13 , which is perforated in several places to allow extension of control components to the exterior of the housing  1 . The source gas passage  12  is preferably valved, preferably by the use of a screw  14 , the degree to which partially or completely blocks the source gas passage  12  depending on the depth to which the screw  14  has been adjusted into a partially threaded hole in the housing  1 , intersecting the source gas passage  12 . Alternatively, the gas feed passage  9  may be similarly valved instead of, or in addition to, the source gas passage  12  to control flow both between the source gas passage  12  and breech  3 , and between the source gas passage  12  and valve passage  8 . The screw  14  must form a seal with the hole in which it  14  sits, preferably by the use of one or more o-rings in grooves  15 . The source gas passage  12  will preferably include an expanded section  16  to minimize liquid entry and maximize consistency of entering gas by acting as a plenum. Gas is introduced through the source gas passage inlet  17  at the base of the housing  1 , which may be designed to accept any high pressure fitting. A gas cylinder, which may be mounted to the housing  1 , preferably to the base of the housing  1  in front of the optional trigger guard  18  illustrated in FIG. 1 or immediately to the rear of the source gas passage inlet  17 , may be connected to said fitting, preferably by a flexible high pressure hose. The source gas passage  12  is depicted preferably integrated into the lower rear part of the housing  1  to facilitate manufacture of the housing  1  from a single piece of material, but it is to be appreciated that any orientation of the source gas passage  12 , either within the housing  1  or an attachment made to the housing  1  of the compressed gas-powered projectile accelerator of the present invention, will not alter the inventive concepts and principles embodied therein.  
         [0062]    A sectional view from the side of the housing with most internal components removed is shown in FIG. 4 for clarity. Optional test/bleed ports  19 ,  20 ,  21  are shown connecting the breech  3  to the outside of the housing  1 , blocked by removable plugs  22 ,  23 ,  24  because they are formed as part of manufacture of the gas feed passage  9 , bolt rest-point passage  10 , and rear passage  11  of this preferred embodiment. Said ports  19 ,  20 ,  21  and plugs  22 ,  23 ,  24  are optional because they are not required for correct function of the projectile accelerator of the present invention. Said ports  19 ,  20 ,  21  may be eliminated from the design by a variety of means, such as the welding shut of said ports  19 ,  20 ,  21 , use of special tooling, or by strategic routing of the gas feed passage  9 , the bolt rest-point passage  10 , and/or, in particular, the rear passage  11  which may be oriented such that it  11  may be drilled either from the rear of the breech  3  or from the bottom. The breech  3  is shown to advantage in FIG. 5. In FIG. 6 the breech  3  is shown to advantage with the front test/bleed port  19  and middle test/bleed port  20  eliminated by welding and rear passage  11  oriented such that it  11  may be manufactured without additional perforation of the breech  3  or need of special tooling such as a small right-angle drill. A third option is shown in FIG. 7 where the bolt rest-point passage  10 , and rear passage  11  are replaced by a single slot  25 , eliminating the corresponding perforations at the top of the breech  3 .  
         [0063]    Passages  9 ,  10 ,  11  and/or bleed/test ports  19 ,  20 ,  21  may be individually optionally valved to control gas flow, preferably by the use of screws, the degree to which partially or completely block the passage or passages  9 ,  10 , and/or  11 , and/or bleed/test ports  19 ,  20 , and/or  21 , depending on the depth to which the screws have been adjusted into threaded holes appropriately made in the housing  1 , intersecting the passage or passages  9 ,  10 , and/or  11  and/or ports  19 ,  20 , and/or  21 . The preferred embodiment depicted in the figures herein includes an exemplary valve screw  26  at the junction between the rear passage  11  and valve passage  8 .  
         [0064]    Referring now to FIG. 8, a hollow slider, having one or, as shown in FIG. 8, a plurality of holes  27  on the front surface, matching the shape of the barrel  4  and breech  3 , preferably free to rotate about a central axis parallel to the receiver passage  2  to minimize wear, and preferably made of a single piece, generally referred to as a bolt  28 , can slide within the receiver passage  2  and around a preferably cylindrical spring-guide  29 , which has a hollow space at the forward end which communicates with said forward end a plurality of holes about its  29  circumference which allow compressed gas to pass through the bolt  28  and will hence be denoted “purge holes”  30 . A preferably elastic bumper or “bolt bumper”  31  is attached to the bolt  28  at a point where the bolt  28  changes diameter, limiting its  28  forward travel and easing shock in the event of malfunction. (The projectile accelerator of the present invention can be designed such that the bolt  28  does not experience high impact against the housing  1 .) A spring or “bolt spring”  32  surrounds the spring-guide  29 , which is attached, preferably by a screw  33  to a removable breech cap  34 , which closes the rear of the breech  3 , preferably by being screwed into the housing  1 . The bolt  28  and spring guide  29  are shown with preferable o-ring/groove type gas seals  35 ,  36 ,  37 , although the type of sealing required at these locations is arbitrary. A preferably cylindrical elastic bumper  38  which protects the bolt  28  and breech cap  34  in the event of malfunction is held in place between the spring guide  29  and breech cap  34 , partially surrounding the bolt spring  32  and spring guide  29 . The breech cap  34 , bumper  38 , spring guide  29 , bolt spring  32 , and rear part of the bolt  28  and housing  1  are shown to advantage in FIG. 9. Alternate configurations of these components are shown to advantage in FIG. 10, where instead of having a hollow space at the forward end and purge holes  30 , the spring guide  29  is truncated to allow the passage of gas through the bolt  28 ; FIG. 11, where the bolt spring  32  diameter is enlarged to reduce wear on the spring guide o-ring  37  (or other seal type) and the bumper  38  resides partly inside the bolt spring  32 ; and FIG. 12, where the spring guide  29  is again truncated and the purge holes  30  are incorporated into the rear part of the bolt  28 .  
         [0065]    A partially hollow slider or “valve slider”  39  matching the shape of the valve passage  8  as shown in FIG. 8, preferably free to rotate about its  39  axis parallel to the receiver passage  2  to minimize wear, particularly from contact with the sear  40  described below, can slide within the valve passage  8 . The valve slider  39  must form seals with the valve passage  8  at two points where single o-ring/groove type seals  41 ,  42  are shown for illustration, but multiple o-rings or any other appropriate type of seal may be used; e.g. use of a flexible material such as polytetrafluoroethylene at these points to form surface-to-surface seals in lieu of o-rings can potentially reduce wear on these seals  41 ,  42 . A preferably removable, hollow valve passage cap  43 , preferably screwed into the housing  1 , traps an optional bumper or “valve bumper”  44  which protects the valve passage cap  43  from wear by contact with the valve slider  39  and vice-versa. A spring or “valve spring”  45  within the valve passage  8  and partially within the valve slider  39  and valve passage cap  43  pushes against the valve slider  39  and against a screw  46  preferably threaded inside of the valve passage cap  43 , the position of which may be adjusted to increase or decrease tension in the spring  45 , thereby adjusting the operating pressure of the cycle and magnitude of projectile acceleration. An optional internal guide  47  for the valve spring can be added. The valve slider  39  can be held in a forward “cocked” position by a sear  40 , which can rotate about and slide on a pivot  48 . A spring  49  maintains a bias for the sear  40  to slide forward and rotate toward the valve slider  39 . Sliding travel of the sear  40  can be limited by means of a preferably cylindrical sliding cam or “mode selector cam”  50  of varying diameter shown to advantage in FIGS. 14, 15A, and  15 B, the positions corresponding to semi-automatic and fully-automatic being shown in FIGS. 15A and 15B, respectively. Position of the mode selector cam  50  is maintained and its  50  travel limited by the ball  51  and spring  52  arrangement shown, which are retained within the housing  1  by the screw  53  shown.  
         [0066]    A lever or “trigger”  54  which rotates on a pivot  55  can press upon the sear  40 , inducing rotation of the sear  40 . A bias of the trigger  54  to rotate toward the sear  40  (clockwise in FIG. 8) is maintained by spring  56 . Rotation of the trigger  54  can be limited by means of a preferably cylindrical sliding cam or “safety cam”  57  of varying diameter shown to advantage in FIGS. 14, 16A, and  16 B, the firing and non-firing positions being shown in FIGS. 16A and 16B, respectively. Position of the safety cam  57  is maintained and its  57  travel limited by the ball  58  and spring  59  arrangement shown, which are preferably retained within the housing  1  by the screw  60  shown.  
         [0067]    Semi-automatic operation of the compressed gas-powered projectile accelerator of the present invention is here described:  
         [0068]    1. The preferred ready-to-operate configuration for semi-automatic operation is shown in FIG. 17A, with the valve slider  39  in its  39  cocked position, resting against the sear  40 , which, under the pressure of the valve spring  45  translated through the valve slider  39 , rests in its  40  rearmost position. The safety cam  57  is positioned to allow the trigger  54  to rotate freely. The mode selector cam  50  is positioned so as to not restrict the forward travel of the sear  40 . The smaller diameters of the safety cam  57  and mode selector cam  50  are shown in this cross section, as said smaller diameters represent the portions of these components interacting with the trigger  54  and sear  40 , respectively. A projectile  61  with an arbitrary externally applied bias to enter the barrel  4 , here a spherical projectile  61  being used as an example, is prevented from entering the barrel  4  by interference with the bolt  28 .  
         [0069]    2. The trigger  54  is then pulled rearward, pulling the sear  40  downward, disengaging it  40  from the valve slider  39 , as shown in FIG. 17B.  
         [0070]    3. Shown in FIG. 17C, under the force applied by the valve spring  45 , the valve slider  39  then slides rearward, until it  39  is stopped preferably by mechanical interference with the changing diameter of the valve passage  8 , allowing gas to flow through the gas feed passage  9  into the region of the breech  3  ahead of the bolt rear seal  36 . Simultaneously, the sear  40  is caused to slide forward and rotate (clockwise in the drawing) by the sear spring  49 , coming to rest against the valve slider  39 , being now disengaged from the trigger  54 .  
         [0071]    4. Shown in FIG. 17D, the pressure of the gas causes the bolt  28  to slide rearward, until the bolt rear seal  36  passes the front edge of bolt rest-point passage  10 , allowing gas into the bolt rest-point passage  10 , valve passage  8  rearward of the valve slider  39 , rear passage  11 , and region of the breech  3  behind the bolt  28 . The externally applied bias of the projectile  61  to enter the barrel  4 , here assumed to be gravity as an example, acts to push a projectile  61  into the barrel  4 , aided by he suction induced by the motion of the bolt  28 . Additional projectiles in the projectile feed passage  6  are blocked from entering the barrel  4  by the projectile  61  already in the barrel  4 . The combined force of the bolt spring  32  and the pressure behind the bolt  28  bring the bolt  28  to rest, preferably without contacting the breech cap bumper  38  at the rear of the breech  3 . The breech  3 , valve passage  8  rearward of the valve slider  39 , and all contiguous cavities not isolated by seals within the housing  1  may here be recognized as the intermediate reservoir discussed in the background of the invention. The bolt  28  will remain approximately at rest, where its  28  position will only adjust slightly to allow more or less gas through the bolt rest-point passage  10  as required to maintain a balance of pressure and spring forces on it  28  while the pressure continues to increase.  
         [0072]    5. Shown in FIG. 17E, once the pressure in the valve passage  8  rearward of the valve slider  39  has increased sufficiently to overcome the force of the valve spring  45  on the valve slider  39 , the valve slider  39  will be pushed forward until it  39  contacts the valve bumper  44  if present, or valve passage cap  43  if no valve bumper  44  is present, thereby simultaneously stopping the flow of compressed gas from the source gas passage  12 , and allowing the flow of gas from the region of the breech  3  ahead of the bolt rear seal  36  through the feed passage, into the valve passage  8  rearward of the valve slider  39 , which is in communication with the region of the breech  3  behind the bolt  28 . The sear  40 , under the action of the sear spring  49 , will rotate further (clockwise in the drawing) once the largest diameter section of the valve slider  39  has traveled sufficiently far forward to allow this, coming to rest against the portion of the valve slider  39  rearward of its  39  said largest diameter section.  
         [0073]    6. The bolt  28  is then driven forward by now unbalanced pressure and spring forces on its  28  surface, pushing the projectile  61  forward in the barrel  4  and blocking the projectile feed passage  6 , preventing the entry of additional projectiles. When the bolt  28  reaches the position shown in FIG. 17F, gas flows through the purge holes  30  in the spring guide  29 , through the center of the bolt  28 , and through the plurality of holes  27  on the front surface of the bolt  28 , which distribute the force of the flowing gas into uniform communication with the rear surface of the projectile  61 .  
         [0074]    7. Shown in FIG. 17G and continued in FIG. 17H, the action of the gas pressure on the projectile  61  will cause it  61  to accelerate through and out of the barrel  4  and barrel extension  5 , at which time the barrel, barrel extension  5 , breech  3 , valve passage  8  rearward of the valve slider  39 , and all communicating passages which are not sealed will vent to atmosphere.  
         [0075]    8. Shown in FIG. 17H, when the pressure within the valve passage  8  rearward of the valve slider  39  has been reduced to sufficiently low pressure such that the force induced on the valve slider  39  no longer exceeds that of the valve spring  45 , the valve slider  39  will slide rearward until its  39  motion is restricted by the sear  40 . The sear  40  will rest against the front of the trigger  54 , and may exert a (clockwise in drawing) torque helping to restore the trigger  54  to its  54  resting position, depending on the design of the position of the trigger pivot  55  relative to the point of contact with the valve slider  39 .  
         [0076]    9. Under the action of the bolt spring  32 , the bolt  28  will continue to move forward, compressing gas within the space ahead of the bolt rear seal  36  in so doing, and, allowing only a small gap by which the gas may escape into the valve passage  8 , the bolt  28  will be decelerated, minimizing wear on the bolt bumper  31  and stopping in its  28  preferred resting position, as shown in FIG. 17I.  
         [0077]    10. When the trigger  54  is released, the action of the trigger spring  56 , sear spring  49 , and valve spring  45  will return the components to the preferred ready-to-fire configuration, shown in FIG. 17A.  
         [0078]    Fully-automatic operation of the compressed gas-powered projectile accelerator of the present invention is here described:  
         [0079]    1. The preferred ready-to-operate configuration for fully-automatic operation is shown in FIG. 18A, with the valve slider  39  in its  39  cocked position, resting against the sear  40 , which, under the pressure of the valve spring  45  translated through the valve slider  39 , rests in its  40  rearmost position. The safety cam  57  is positioned to allow the trigger  54  to rotate freely. The mode selector cam  50  is positioned so as to restrict the forward travel of the sear  40 . The smaller diameter of the safety cam  57  and larger diameter of the mode selector cam  50  are shown in this cross section, as said diameters represent the portions of these components interacting with the trigger  54  and sear  40 , respectively. A projectile  61  with an arbitrary externally applied bias to enter the barrel  4 , here a spherical projectile being used as an example, is prevented from entering the barrel  4  by interference with the bolt  28 .  
         [0080]    2. The trigger  54  is then pulled rearward, pulling the sear  40  downward, disengaging it  40  from the valve slider  39 , as shown in FIG. 18B.  
         [0081]    3. Shown in FIG. 18C, under the force applied by the valve spring  45 , the valve slider  39  then slides rearward, until it  39  is stopped preferably by mechanical interference with the changing diameter of the valve passage  8 , allowing gas to flow through the gas feed passage  9  into the region of the breech  3  ahead of the bolt rear seal  36 . The mode selector cam  50  prevents the sear  40  from sliding forward sufficiently far to disengage from the trigger  54 .  
         [0082]    4. Shown in FIG. 18D, the pressure of the gas causes the bolt  28  to slide rearward, until the bolt rear seal  36  passes the front edge of the bolt rest-point passage  10 , allowing gas into the bolt rest-point passage  10 , valve passage  8  rearward of the valve slider  39 , rear passage  11 , and region of the breech  3  behind the bolt  28 . The externally applied bias of the projectile  61  to enter the barrel  4 , here assumed to be gravity as an example, acts to push a projectile  61  into the barrel  4 , aided by the suction induced by the motion of the bolt  28 . Additional projectiles in the projectile feed passage  6  are blocked from entering the barrel  4  by the projectile  61  already in the barrel  4 . The combined force of the bolt spring  32  and the pressure behind the bolt  28  bring the bolt  28  to rest, preferably without contacting the breech cap bumper  38  at the rear of the breech  3 . The breech  3 , valve passage  8  rearward of the valve slider  39 , and all contiguous cavities not isolated by seals within the housing  1  may here be recognized as the intermediate reservoir discussed in the background of the invention. The bolt  28  will remain approximately at rest, where its  28  position will only adjust slightly to allow more or less gas through the bolt rest-point passage  10  as required to maintain a balance of pressure and spring forces on it  28  while the pressure continues to increase.  
         [0083]    5. Shown in FIG. 18E, once the pressure in the valve passage  8  rearward of the valve slider  39  has increased sufficiently to overcome the force of the valve spring  45  on the valve slider  39 , the valve slider  39  will be pushed forward until it  39  contacts the valve bumper  44  if present, or valve passage cap  43  if no valve bumper  44  is present, thereby simultaneously stopping the flow of compressed gas from the source gas passage  12 , and allowing the flow of gas from the region of the breech  3  ahead of the bolt rear seal  36  through the feed passage, into the valve passage  8  rearward of the valve slider  39 , which is in communication with the region of the breech  3  behind the bolt  28 .  
         [0084]    6. The bolt  28  is then driven forward by now unbalanced pressure and spring forces on its  28  surface, pushing the projectile  61  forward in the barrel  4  and blocking the projectile feed passage  6 , preventing the entry of additional projectiles. When the bolt  28  reaches the position shown in FIG. 18F, gas flows through the purge holes  30  in the spring guide  29 , through the center of the bolt  28 , and through the plurality of holes  27  on the front surface of the bolt  28 , which distribute the force of the flowing gas into uniform communication with the rear surface of the projectile  61 .  
         [0085]    7. Shown in FIG. 18G and continued in FIG. 18H, the action of the gas pressure on the projectile  61  will cause it  61  to accelerate through and out of the barrel  4  and barrel extension  5 , at which time the barrel  4 , barrel extension  5 , breech  3 , valve passage  8  rearward of the valve slider  39 , and all communicating passages which are not sealed will vent to atmosphere.  
         [0086]    8. When the pressure within the valve passage  8  rearward of the valve slider  39  has been reduced to sufficiently low pressure such that the force induced on the valve slider  39  no longer exceeds that of the valve spring  45 , the valve slider  39  will begin to slide rearward. If the trigger  54  has not been allowed by the operator to move sufficiently far forward to allow the sear  40  to interfere with the rearward motion of the valve slider  39 , the valve slider  39  will continue to move rearward as described in Step 3, and the cycle will begin to repeat, starting with Step 3. If the trigger  54  has been allowed by the operator to move sufficiently far forward to allow the sear  40  to interfere with the rearward motion of the valve slider  39 , the valve slider  39  will push the sear  40  rearward into the preferred resting position and will come to rest against the sear  40  as shown in FIG. 18H, and the cycle will proceed to Step 9 below.  
         [0087]    9. Under the action of the bolt spring  32 , the bolt  28  will continue to move forward, compressing gas within the space ahead of the bolt rear seal  36  in so doing, and, allowing only a small gap by which the gas may escape into the valve passage  8 , the bolt  28  will be decelerated, minimizing wear on the bolt bumper  31  and stopping in its  28  preferred resting position, at which point all components will now be in their original ready-to-fire configuration, shown in FIG. 18A.  
         [0088]    Cocking:  
         [0089]    Whereas most compressed gas-powered projectile accelerators known to be in the art require a means of manual cocking, the compressed gas-powered projectile accelerator of the present invention will automatically cock when compressed gas, from a source mounted on any location on the housing  1  or other source, is introduced, preferably through a tube, attached to the source gas passage inlet  17 . If said compressed gas-powered projectile accelerator of the present invention is un-cocked (i.e. the valve slider  39  is not resting against the sear  40 , but further rearward under the action of the valve spring  45 ) when compressed gas is introduced through the source gas passage  12 , said gas will flow through the source passage  12 , valve passage  8 , and gas feed passage  9  into the region of the breech  3  ahead of the bolt rear seal  36 , and one of the semi-automatic or fully automatic cycles above described will ensue at Step 4, the particular cycle being determined by the position of the mode selector cam  50 . The automatic cocking feature reduces potential contamination of the compressed gas-powered projectile accelerator of the present invention because said feature removes the necessity the additional perforation of the housing  1  to accommodate the connection of a means of manual cocking to internal components, which constitutes a common path by which dust and debris may enter the housing  1  of many compressed-gas powered projectile accelerators known to be in the art.  
         [0090]    This is not to imply that a means of manual cocking may not be employed to advantage, but should here be considered optional to the compressed gas-powered projectile accelerator of the present invention, as the addition of a means of manual cocking will allow the operator to bring the compressed gas-powered projectile accelerator of the present invention into a cocked state without cycling, and, more specifically, silently, without the audible report that will be associated with allowing the compressed gas-powered projectile accelerator of the present invention to automatically cock by completing a cycle. The simplest method of applying a manual cocking mechanism to the compressed gas-powered projectile accelerator of the present invention is shown to advantage in FIGS. 19 and 20, where a knob  62  is attached, preferably by a screw  63 , to the valve slider  39 , which protrudes through a slot  64  in the housing  1 . However, because the presence of the slot  64  decreases the resistance to contamination and the cocking knob  62  increases wear on the valve slider  39  by not allowing it  39  to freely rotate with respect to points of intermittent contact with the sear  40 , a preferred option is shown in FIGS. 21 and 22, where a manifold  65  attached to the housing  1  holds a cocking slider  66  which penetrates the housing  1  through a slot  64  such that the pushing forward of said cocking slider  66  will cause the valve slider  39  to move forward into a cocked position. The cocking slider manifold  65  obstructs the path of debris into the slot  64  in the housing  1 . A spring  67  biases the cocking slider  66  to remain out of the path of the valve slider  39  during operation.  
         [0091]    The two examples provided are intended to be illustrative as it is to be appreciated that there are numerous obvious methods by which a means of manual cocking (such as the addition of any appendage to the valve slider  39  which may be manipulated from the housing  1  exterior, particularly by protrusion from the front or rear of the valve passage  8 ) may be incorporated into the projectile accelerator of the present invention without altering the inventive concepts and principles embodied therein.  
         [0092]    Expansion Chamber or Second Regulator in Source Gas Passage  12 :  
         [0093]    One distinct advantage of this preferred embodiment of the compressed gas-powered projectile accelerator of the present invention is that, because the housing  1  can preferably made from a single piece of material, a feed gas conditioning device can easily be incorporated into the housing  1 , preferably inserted into the expanded section of the source gas passage  16 , shown to advantage in FIG. 23, whereas for compressed gas-powered projectile accelerators known to be in the art, such devices are typically contained in separate housings which are typically either screwed into or welded to the primary housing.  
         [0094]    In FIG. 24 the source gas passage  12  of the compressed gas-powered projectile accelerator of the present invention is shown to advantage with the option of baffle inserts  68  within the expanded section of the source gas passage  16  to reduce the potential for liquid to enter the valve passage  8 . A spring  69  placed between the lowest baffle insert and a fitting  70  installed at the source gas passage inlet  17  acts to retain the baffle inserts  68  in position.  
         [0095]    In FIG. 25 the source gas passage  12  of the compressed gas-powered projectile accelerator of the present invention is shown with the option of an additional feed gas regulator inserted into the expanded section of the source gas passage  16 , where a spring  71  pushes a preferably cylindrical and preferably beveled slider  72 , perforated with a plurality of holes, against a matching seat  73 , which is sealed against the wall of the expanded section of the source gas passage  16  by arbitrary means, and exemplified by o-ring/groove type seals  74  in FIG. 25. The position of the seat  73  is maintained by threads engaging the wall of the expanded section of the source gas passage  16 , which is correspondingly threaded, and rotation of the seat  73  (which has a hexagonally shaped groove designed to match a standard hexagonal key wrench), causing it  73  to thread more or less deeply into the expanded section of the source gas passage  16 , allows adjustment of the spring  71  tension, thereby adjusting the equilibrium downstream (spring  71  side) pressure.  
         [0096]    Pneumatically Assisted Feed:  
         [0097]    In FIGS.  26 - 29  the compressed gas-powered projectile accelerator of the present invention with the option of an added pneumatic feed-assist tube  75  which re-directs a preferably small portion of gas from the breech  3  to increase the bias of projectiles to enter the barrel  4  is shown used in conjunction with a gravitationally induced bias. The pneumatic feed-assist tube  75  can increase the rate of entry of projectiles into the barrel  4 , allowing the cycle to be adjusted to higher rates than is possible without the addition of said pneumatic feed-assist tube  75 . The pneumatic feed-assist tube  75  may be attached in such a way to communicate with any point in any passage within the compressed gas-powered projectile accelerator of the present invention, the shown preferred position being exemplary, and may optionally be incorporated as an additional passage within the housing. The amount of gas which is redirected can be metered by the internal cross-sectional area of the pneumatic feed-assist tube  75  and/or connecting fittings  76 ,  77 , and/or by optional adjustable valving integrated into the pneumatic feed-assist tube  75  and/or connecting fittings  76 ,  77  (not shown for clarity).  
         [0098]    Alternate Bolt Resting Positions:  
         [0099]    While the preferred embodiment of the compressed gas-powered projectile accelerator of the present invention has been shown depicting the preferred resting position of the bolt  28  in its  28  most forward travel position because this takes advantage of the bolt  28  to prevent the entry of more than one projectile into the barrel  4  between cycles, it is to be appreciated that small changes in the configuration of the bolt  28 , bumpers  31 ,  38 , and bolt spring  32  can cause the bolt  28  to rest in a different location between cycles without changing the basic operation of the compressed gas-powered projectile accelerator of the present invention. If the bolt spring  32  is placed in front of the larger diameter section of the bolt  28 , instead of behind as in FIG. 3, the bolt  28  will be biased to rest against the breech cap bumper  38  at the rear of the breech  3  between cycles. Alternatively, a combination of springs, one ahead and one behind the larger diameter section of the bolt  28 , may be used to bias the bolt  28  toward any resting position between cycles, depending on the length and relative stiffness of the two springs. Changes in the resting position of the bolt  28  will alter the initial motion of the bolt  28  which in all cases will move the bolt  28  toward the position described in Step 4 of both the semi-automatic and fully-automatic cycle descriptions with the bolt rear seal  36  just behind the front edge of the bolt rest-point passage  10 . Correspondingly, at the end of the last cycle, the bolt  28  will return to the altered rest position rather than the rest position described in the preferred embodiment. In all other respects, both semi-automatic and fully-automatic operation will be identical to as above described. If the bolt  28  is retained at rest in a position that does not prevent projectiles from entering the barrel  4  between cycles, some provision must be included to prevent projectiles from prematurely moving down the barrel  4 . This may be accomplished frictionally, by a close fit of projectiles to the barrel  4  diameter, or by the addition of a conventional spring biased retention device which physically blocks premature forward motion of projectiles in the barrel  4 .  
         [0100]    Additional Cavities:  
         [0101]    It is to be appreciated that the operating characteristics of the compressed gas-powered projectile accelerator of the present invention may be altered by the addition of supplementary cavities, either within the housing or attachments made to the housing, contiguous in any place with any of the internal passages of the apparatus without altering the inventive concepts and principles embodied therein. These cavities may be of fixed or variable volume. (Operating characteristics can be altered by changing the cavity volume.) An example of a compressed gas-powered projectile accelerator made according to the present invention with the addition of a variable volume is illustrated in FIGS. 30 and 31, where a threaded passage  78 , parallel and connected to the valve passage  8 , is closed at the rear by a threaded plug  79 , and at the front by a screw  80 , the position of which may be adjusted within the threaded passage  78  to vary the volume. In particular, the threaded passage  78  as shown in FIGS. 30 and 31 may be connected to the valve passage  8 , as shown, or, alternatively, to the gas feed passage  9 , so that the gas volume may be varied in order to change the amount of acceleration applied to projectiles in lieu of, or in addition to, other means to control the same, already and to be further described.  
         [0102]    Pneumatic Valve Slider Bias:  
         [0103]    It is to be appreciated that the operating characteristics of the compressed gas-powered projectile accelerator of the present invention may be altered such that the bias of the valve slider  39  is induced by the pressure of compressed gas, rather than by a valve spring  45 , without altering the inventive concepts and principles embodied therein, as shown in FIG. 32, where the compressed gas-powered projectile accelerator made according to the present invention is shown in FIG. 31 with the valve spring  45  omitted and the valve slider  39  geometry modified with an extension and pair of preferably o-ring type seals  81 ,  82  to allow the valve slider  39  to be pneumatically biased to move rearward when compressed gas is introduced into the volume  83  between the seals  81 ,  82 . FIG. 32 depicts gas communication into this volume  83  to be through a fitting  84  threaded into a hole through the housing  1  as an example, but the routing of gas, preferably from the source connected to the source gas passage  12 , is arbitrary. The changes in the valve slider  39  geometry allow the valve slider bumper  44  to be placed inside the valve passage cap  43 , which is shown with a preferable o-ring type seal  85  to prevent gas leakage. Projectile velocity may be controlled either by regulation by arbitrary means (e.g., by a regulator within the expanded portion of the gas feed passage  16 , previously described, provided the gas is tapped downstream of the regulator) of the pressure in the volume  83  between of the valve slider seals  81 ,  82 , or by an adjustable volume, as previously described. Operation is as previously described except that the bias for the valve slider  39  to move rearward is provided by the pressure of gas within the volume  83  between of the valve slider seals  81 ,  82  rather than by a spring.  
         [0104]    Electronic Embodiment of the Compressed Gas-Powered Projectile Accelerator of the Present Invention:  
         [0105]    It is to be appreciated that the operating characteristics of the compressed gas-powered projectile accelerator of the present invention may be altered by the replacement of the valve and internal trigger mechanism components shown in the non-electronic preferred embodiment with electronic components without altering the inventive concepts and principles embodied therein, as shown in FIGS. 33 and 34. In FIG. 34, the valve and internal trigger mechanism components are shown replaced by a spring biased (toward the closed position) solenoid valve, consisting of a valve body  86 , valve slider  87  with seals  88 ,  89  (similar to the valve slider  39  in the non-electronic preferred embodiment), spring  90 , coil  91 , and bumper  92 ; electronic switch  93 ; battery  94  (or other power source); and control circuit  95 ; where the opening force applied to the solenoid valve slider  87  by the coil  91  when energized by the control circuit  95  can be designed such that the pressure within the valve passage  8  rearward of the solenoid valve slider  87  will force the valve into the un-actuated position at the design set pressure, thus simultaneously terminating flow from the source gas passage  12  into the region of the breech  3  ahead of the larger diameter section of the bolt  28  and initiating flow from said region within the breech  3  ahead of the larger diameter section of the bolt  28  into the valve passage  8  rearward of the solenoid valve slider  87  and into the region of the breech  3  behind the bolt  28 , simulating the behavior of the mechanical system already described. The set pressure can be adjusted by adjusting the current in the solenoid valve coil  91 , thereby adjusting the projectile acceleration rate. Because velocity control is electronic, no velocity adjustment screw  46  need be incorporated into the valve passage cap  43 , and the valve passage cap  43  and corresponding bumper  44  need not be hollow. The control circuit  95 , preferably consists of an integrated circuit  96  which performs the cycle control logic, an amplifier  97 , a means of controlling valve coil  91  current, e.g. a variable resistor  98  with a “velocity control dial”  99  protruding to the exterior, and a multi-position switch  100  which can be used to disable the trigger  54  (one switch position), or select between semi-automatic (second switch position) and fully-automatic (third switch position) operation when the trigger  54  is pulled. With the exception of components replaced by the electronic control circuit  95  and solenoid valve components  86 ,  87 ,  88 ,  89 ,  90 ,  91 ,  92 , operation is identical to the non-electronic preferred embodiment (where the solenoid valve slider  87  performs the same role as the valve slider  39  in the non-electronic preferred embodiment). The battery  94  is shown preferably contained within a padded compartment  101  in the housing  1  with a preferably hinged door  102  to allow replacement. An optional mechanical safety cam  57 , identical to that employed on the non-electronic preferred embodiment of the compressed gas-powered projectile accelerator of the present invention, but differently located, is also shown in FIG. 34.  
         [0106]    Alternatively, rather than relying upon the mechanical action of pressure within the valve passage  8  rearward of the solenoid valve slider  87  to push the solenoid valve slider  87  into the closed position, the solenoid valve coil  91  can be de-energized when the set pressure is reached, which can be determined based on timing, or by a signal supplied to the control circuit  95  by a pressure transducer  103  (or other electronic pressure sensor), which can be positioned in communication with the gas behind the solenoid valve slider  87  or in the breech  3  either ahead of or behind the largest diameter section of the bolt  28  (i.e. the intermediate reservoir), as shown in FIGS. 35 and 36, (through wires connecting the pressure sensor  103  to the control circuit  95 , the geometry of which are arbitrary and not shown in the figures for clarity). In these cases, the velocity control dial  99  does not adjust the solenoid valve coil  91  current, but rather the timing, in the case of a timed circuit, or either the signal level from the pressure sensor  103  at which the control circuit  95  de-actuates the solenoid valve coil  91  or the said pressure sensor  103  signal, thereby accomplishing the same effect.  
         [0107]    It is also to be appreciated that additional, optional controls can be incorporated into the control circuit  95  of the preferred electronic embodiment of the compressed gas-powered projectile accelerator of the present invention without altering the inventive concepts and principles embodied therein, such as additional switch  100  positions controlling additional operating modes where the projectile accelerator accelerates finite numbers of projectiles, greater than one, generally known as “burst modes” when the trigger  54  is pulled, as compared to semi-automatic operation, where a single projectile is accelerated per trigger  54  pull, and fully-automatic operation, where projectile acceleration cycles continue successively as long as the trigger  54  remains pulled rearward. Additionally, the timing between cycles can be electronically controlled, and said timing can be made adjustable by the inclusion of an additional control dial in the control circuit  95 .  
         [0108]    Closing Statement:  
         [0109]    Having thus described in detail a preferred embodiment of the compressed gas-powered projectile accelerator of the present invention, it is to be appreciated and will be apparent to those skilled in the art that many physical changes, only a few of which are exemplified in the detailed description of the invention, could be made without altering the inventive concepts and principles embodied therein. It is also to be appreciated that numerous embodiments incorporating only part of the preferred embodiment are possible which do not alter, with respect to those parts, the inventive concepts and principles embodied therein. The present embodiment and optional configurations are therefore to be considered in all respects as exemplary and/or illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all alternate embodiments and changes to this embodiment which come within the meaning and range of equivalency of said claims are therefore to be embraced therein.