Trigger mechanism for compressed gas powered weapons or the like

A compressed gas powered gun includes a firing system capable of achieving increased firing rates. The firing system includes a regulating system by which an air or firing chamber can be charged with compressed gas from a compressed gas source to a predetermined pressure very rapidly. The firing system also includes a trigger mechanism which enables rapid actuation of a trigger by a user.

FIELD OF THE INVENTION 
This invention generally relates to a trigger mechanism, and more 
particularly, to a trigger mechanism for use in compressed gas powered 
weaponry or the like. 
BACKGROUND OF THE INVENTION 
A variety of different types of weaponry which utilize discharged 
compressed gas to fire projectiles are known. These compressed gas powered 
weapons have particular use in a variety of applications including 
tranquilizer guns and pellet marking guns which are sometimes referred to 
as "paint ball guns." Generally marking guns use compressed gas to fire a 
relatively fragile projectile which comprises a frangible shell which is 
filled with a marking composition. The capsules are designed to break upon 
impact with a target and thereby discharge the marking material onto the 
target. 
Such marking guns have a variety of different uses. For example, they may 
be employed to segregate livestock within a herd, assist in the counting 
of wild animals or for training of military or law enforcement personnel 
through simulation exercises. Likewise, they may be used by military and 
law enforcement personnel for crowd control. Another very popular use for 
such marking guns is for recreation. In particular, paint ball marking 
guns are used for "war games" in which participants attempt to hit other 
combatants with paint balls thereby marking them and eliminating them from 
the game. 
One attribute which is extremely important to users of paint ball marking 
guns which are intended for such recreational war games, as well as those 
used for other purposes, is the rate at which the gun may be fired. 
Obviously, paint ball marking guns which are capable of increased firing 
rates offer the user a significant competitive advantage over his/her 
fellow combatants. One significant factor which influences the firing rate 
of any weapon is the type of firing arrangement that is employed. Paint 
ball marking guns typically may employ manual, semi-automatic and fully 
automatic firing arrangements. A manual firing arrangement requires 
appropriate manipulation of the gun before successive projectiles are 
fired. In contrast, a semi-automatic firing arrangement enables a 
projectile to fired each time the trigger is depressed, while an automatic 
firing arrangement will fire multiple projectiles each time the trigger is 
pulled. 
Although fully automatic weapons may seem desirable, they suffer from 
various shortcomings. For example, they consume increased amounts of both 
ammunition and compressed air and have proven problematic, particularly 
due to feeding mechanism failure. Moreover, they have not achieved 
widespread success due to regulation prohibiting their use in many 
recreational settings. 
One important limitation on the firing rate is the physical limitations on 
the speed at which a user can successively pull the trigger. Specifically, 
even if a weapon is capable of handling much higher firing rates, a user 
may not be able to achieve these higher firing rates because he/she simply 
cannot successively pull the trigger fast enough. This limitation is of 
particular importance in the context of semi-automatic firing arrangements 
which are generally preferred in most paint ball competitive tournaments 
since fully the rules typically do not permit automatic firing systems. 
OBJECTS OF THE INVENTION 
Accordingly, in view of the foregoing, it is a general object of the 
present invention to provide a trigger mechanism for a weapon which 
enables rapid actuation of trigger by a user. 
Another object of the present invention is to provided a trigger mechanism 
for compressed gas powered weapons which provides excellent performance 
and is very easy to maintain.

While the invention will be described and disclosed in connection with 
certain preferred embodiments and procedures, it is not intended to limit 
the invention to those specific embodiments. Rather it is intended to 
cover all such alternative embodiments and modifications as fall within 
the spirit and scope of the invention. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Generally, the present invention relates to a firing system for a 
compressed gas powered weapon or the like which is capable of being 
operated at increased firing rates as compared to known firing systems. 
These increased firing rates are achieved through a novel trigger 
mechanism which is incorporated into the firing system of the present 
invention and which helps a user overcome physical limitations which 
otherwise prevent the user from achieving increased firing rates. In 
particular, the trigger mechanism actually assists the user in 
successively actuating the trigger to thereby take advantage of the 
increased firing rates achieved by the firing system of the present 
invention. 
In one preferred embodiment, the firing system also includes a compressed 
gas regulating system which enables an air chamber such as a firing 
chamber of a compressed gas powered weapon to be rapidly filled to a 
preselected pressure from a compressed gas source having a pressure higher 
than the preselected pressure. This invention is also disclosed in patent 
application Ser. No. 08/955,187, filed on the same date as the present 
application, entitled "Pressure Regulating System For Compressed Gas 
Powered Weapons Or The Like," and is incorporated herein by reference in 
its entirety. In the context of a compressed gas powered weapon, such 
rapid filling or charging of the firing chamber allows the weapon to 
achieve increased firing rates without adversely affecting the accuracy of 
the gun. 
While the present invention is described in connection with a compressed 
gas powered gun, which has particular use a paint ball marking gun, it 
will be readily appreciated that the teachings of the present invention 
can also be applied in other contexts. These include, for example, other 
types of compressed gas powered weapons. The regulating system of the 
present invention may be utilized in many applications other than 
compressed gas powered weapons. In particular, the regulating system may 
be employed in any application where it is desirable to rapidly fill a 
chamber with a compressed gas to a preselected pressure. Similarly, it 
will be appreciated that the trigger mechanism of the present invention 
could be utilized in weapons other than simply compressed gas powered 
weapons. 
FIGS. 1-6 illustrate one preferred embodiment of a compressed gas powered 
gun which incorporates the firing system of the present invention. Certain 
details of the gun are also disclosed in U.S. Pat. No. 5,280,778, which is 
incorporated herein by reference in its entirety. As best shown in FIG. 1, 
the gun 10 comprises a longitudinally extending frame support or rail 12 
with a trigger-guard 14 and handle 16 depending therefrom. A pivotally 
mounted trigger 18, the operation of which is described in more detail 
below, is disposed within the trigger-guard 14. The firing system is 
operable in a firing mode wherein a projectile is expelled from the gun 
and a ready-to-fire or reloading mode which places the gun in condition 
for firing. As seen in FIG. 2, a projectile 20, such as a marking pellet 
or paint ball, exits an elongate, generally cylindrical barrel 22 in the 
direction of arrow 24 during the firing mode. An ammunition feeding tube 
26 (FIG. 1) is disposed to supply a plurality of projectiles in a manner 
in which the projectiles are fed to the gun, one at a time, as will be 
understood by those skilled in the art. 
For providing connection of the gun to a source of compressed gas, the gun 
includes an inlet port 30 which in the preferred embodiment comprises a 
conventional adapter which allows an air line or hose (not shown) to be 
quickly and easily connected and disconnected from the gun. The source of 
the compressed gas preferably comprises a tank of compressed air (not 
shown) as will be understood by those skilled in the art. In order to 
provide for ease of movement, the compressed air tank could be strapped to 
the back of the user or could carried on a belt. The compressed gas source 
preferably is supplied at a pressure of approximately 700 pounds per 
square inch (psi). Of course, it should be appreciated that different 
types of sources of compressed gas could be used with the present 
invention. In addition, while compressed air is preferred, other 
compressed gases such as nitrogen may be used. 
The compressed gas or air passes from the inlet port 30 via an annular 
inlet passageway 32 which, in the illustrated embodiment, extends along 
the rail of the frame 12. This inlet passageway provides a passageway to a 
compressed gas delivery system which operates to control and meter the 
compressed gas received from the compressed gas source in both the firing 
and ready-to-fire modes of the firing system. Specifically, the compressed 
gas delivery system includes a pressure regulating system or assembly 34 
and a fluid pathway which interconnects the compressed gas inlet port 28 
with an air or firing chamber 36. 
In accordance with one aspect of the present invention, a pressure 
regulating assembly is adapted to rapidly recharge the firing chamber 
after it is expelled by filling at an increased pressure until a 
preselected pressure is attained. In the illustrated embodiment, the 
pressure regulating assembly 34 is adapted to operate at a very high speed 
and provide for full pressure recharge of the firing chamber 36. This 
results in the firing chamber 36 being charged with compressed gas to the 
preselected pressure very rapidly thereby increasing the potential firing 
rate of the gun 10. 
The pressure regulating assembly 34 and the fluid pathway are disposed in a 
cylindrical terminal housing or valve body section 38 of the gun. The 
regulating assembly 34 generally comprises a screw-type control and valve 
arrangement including a valve 40 disposed in the fluid pathway 
interconnecting the inlet port 30 and the firing chamber 36 and a 
regulator piston subassembly 42. The main structural details of the valve 
40 include a head portion 44, a valve stem 46, a seat 48 and a biasing 
spring 50. A generally cylindrical regulator valve chamber 52 is formed in 
the valve body section 38 of the gun which is in fluid communication with 
the inlet passageway 32 via a fluid passageway 54 provided in the field 
strip screw 55. The valve head 44 is contained within the regulator valve 
chamber 52 while one end of the stem portion 46 extends outwardly to the 
regulator piston subassembly 42. 
The valve 40 is operable to move between an open position, wherein 
compressed gas flows from the inlet port 30 to the firing chamber 36 via 
the fluid pathway and a closed position, wherein the inlet port 30 is 
isolated from the firing chamber 36. Specifically, when the valve 40 is in 
the closed position, the valve head 44 engages the valve seat 48 to 
thereby close off the flow of compressed gas to the firing chamber 36 as 
shown in FIG. 3. When the valve 40 is in the open position, compressed gas 
flows between the outer periphery of the valve head 44 and the walls of 
the regulator valve chamber 52 as shown in FIG. 2. The flow of compressed 
gas past the valve 40 continues to an on/off flow valve chamber 56 via a 
fluid passageway 58. In turn, the flow valve chamber 56 is interconnected 
with the firing chamber 36 by way of a second fluid passageway 60 which 
completes the fluid pathway between the inlet port 30 and the firing 
chamber 36. 
In order to control the pressure in the firing chamber 36, the regulator 
piston subassembly 42 is adapted to move the valve 40 to the closed 
position (FIG. 3) when a predetermined pressure of compressed gas is 
sensed and to urge the valve 40 to an open position when a pressure less 
than the preselected pressure is sensed. The regulator piston subassembly 
42 is arranged in a regulator piston bore 62 which is sealed from the flow 
of gas from the regulator valve chamber 52. In order to prevent gas from 
leaking into the regulator piston bore, around the valve stem an o-ring 
seal 64 is provided. The main structural components of the regulator 
piston subassembly include a threaded adjusting nut 66, a biasing spring 
68 and a regulator piston 70. 
In the preferred embodiment, a blow off valve arrangement valve is provided 
which includes a head 67 and biasing spring 69. When an over-pressure 
condition is sensed, the valve permits the compressed to vent to 
atmosphere via an overflow port 73. 
In order to sense the pressure of the gas in the firing chamber 36, the 
regulating assembly 34 further includes a sensing line 72. The sensing 
line 72 is in fluid communication with the regulator piston bore 62 and is 
adapted to apply the pressure of the gas in the firing chamber 36 to the 
regulator piston subassembly 42. In a preferred embodiment, the forward 
end of the valve stem 46 extends to a location adjacent the firing chamber 
36 and the sensing line 72 comprises a bore in the valve stem 46 which 
extends from adjacent the firing chamber 36 to the regulator piston bore 
62 as shown in FIGS. 2-6. 
When the firing chamber 36 is being filled or charged with compressed gas 
during the ready-to-fire mode of the firing system, the regulating springs 
68, 69 bias the regulator piston 70 toward a forward position in the 
piston bore 62, which in turn, acts to move the valve head 44 away from 
the valve seat 48 as best shown in FIG. 2. The regulator piston 70 remains 
in this forward position and thereby prevents the valve 40 from closing 
until a predetermined pressure is supplied to the firing chamber 36 and to 
the piston bore 62 via the sensing line 72. When the pressure in the 
firing chamber 36 and the piston bore 62 reach the predetermined pressure, 
as shown in FIG. 3, the regulator piston 70 is moved counter to the force 
of the regulator springs 68, 69 to a rearward position which causes the 
valve 40 to engage the valve seat 48 and seal the regulator valve chamber 
52. The compressed gas in the portion of the fluid pathway upstream from 
the valve head 44 and the biasing spring 50 coact to maintain a closure 
tension on the valve 40. 
When the pressure in the air chamber 36 and, in turn, in the regulator 
piston bore once again falls below the predetermined pressure such as 
after a firing sequence, the regulating piston subassembly 42 urges the 
valve 40 to an open position as shown in FIGS. 5-6. Compressed gas 
supplied to the regulator piston bore 62 via the sensing line 72 
thereafter acts against the tension of the regulating springs 68, 69 to 
move the piston 70 rearward. Thus, compressed gas is again discharged 
until the pressure in the air chamber 36 reaches the predetermined level 
sufficient to urge the valve 40 closed. 
The operation of the compressed gas delivery system including the 
regulating system of the present invention is perhaps best understood by 
reference to the block diagram of FIG. 7. In contrast to conventional 
arrangements in which the compressed gas is regulated to a lower pressure 
as soon as it enters the gun or the compressed gas delivery system, the 
present invention "regulates" the pressure in the firing chamber 36 itself 
by shutting of the supply of compressed gas when the firing chamber 36 
reaches the desired pressure. Thus, the regulating system of the present 
invention allows the firing chamber 36 to charge at very nearly the full 
line pressure of the compressed gas source. As can be appreciated, this 
allows the firing chamber to fill with compressed gas to the desired 
pressure much more rapidly than conventional designs. As shown in the 
block diagram of FIG. 7, this is accomplished, at least in part, by 
drawing off the compressed gas which acts on the regulator piston 70 from 
a location adjacent the firing chamber 36. Drawing off, or sensing, the 
pressure at this point, as opposed to as soon as it passes the valve, 
eliminates the problem of the flow of gas slowing substantially through a 
nearly closed regulator valve as the pressure in the system nears the 
desired pressure. For example, while known regulating systems in 
compressed gas powered guns limited the firing rate to no more than five 
rounds per second before the projectile velocity started to drop off, in 
one preferred embodiment the regulating system of the present invention is 
capable of achieving a firing rate of twenty-five rounds per second with 
no velocity drop-off. 
This arrangement also ensures precise operation of the gun 10 for 
successive firings over a wide range of ambient temperatures. For example, 
when the ambient temperature increases, thereby increasing the gas 
pressure in firing chamber 36 and the piston bore 62, the regulator piston 
70 is urged rearward to close the valve 40. If the ambient temperature 
increases to a level where the pressure in the piston bore 62 exceeds the 
desired firing chamber pressure and the gas supply pressure by a 
sufficient amount, i.e., 650 p.s.i., the overflow valve will move 
sufficiently rearwardly to permit venting through the port 73. Conversely, 
when the ambient temperature decreases, thereby decreasing the pressure in 
the firing chamber 36 and the piston bore 62, the gas supply pressure 
decreases, urging the valve 40 to an open position. In this way, the 
pressure regulating assembly 34 operates to maintain a desired pressure 
supplied to the air chamber 36 for each firing of the gun. 
In order to allow for the adjustment of the pressure to which the firing 
chamber 36 is charged, and thereby the velocity of the projectile 20, 
means are provided for adjusting the pressure at which the regulator valve 
40 closes. Specifically, in the illustrated embodiment, the amount of 
force exerted by the first regulating spring 68 on the regulating piston 
70 can be controlled through manual adjustment of a threaded velocity nut 
66 provided on the end of the valve body 38. For example, in order to 
increase the pressure to which the firing chamber 36 is charged, the 
velocity nut 66 is turned so as to increase the force that the first 
regulating spring 68 applies to the regulating piston 70. A relatively 
higher pressure will then be required to urge the regulating piston 70 
rearward and thereby close the valve 40. In a preferred embodiment, the 
pressure regulating assembly 34 should be set to shut off the flow of 
compressed gas from the inlet port 30 when the pressure in the air chamber 
36 reaches approximately 450 psi. 
In order to protect against an over pressure condition in the compressed 
gas delivery system resulting from a seal failure or the disassembly of 
the gun when the firing system is under pressure, the blow off valve and 
over pressure vent 73, discussed above, may also be provided. 
It will be appreciated from the foregoing description that the compressed 
gas delivery system and, in particular, the pressure regulating system of 
the present invention may also have application outside of the context of 
compressed gas powered weapons. In fact, the compressed gas delivery 
system of the present invention could be used in any application where the 
object is rapidly charging an air chamber with compressed gas to a 
preselected pressure. 
In order to ensure that the preselected pressure is maintained in the 
firing chamber 36 for the firing mode, the firing system further includes 
a on/off valve 74 which seals off the firing chamber 36 from the 
compressed gas source when the firing system is operating in the firing 
mode. The on/off flow valve 74 is movable between open and closed 
positions and, in particular, is operable to open and thereby permit fluid 
communication between the firing chamber 36 and the inlet port 30 in the 
ready-to-fire mode of operation, as shown in FIG. 2. This enables the 
firing chamber 36 to be charged with compressed gas to the predetermined 
pressure via the compressed gas delivery system during the ready-to-fire 
mode. In the firing mode of operation, the on/off flow valve 74 closes 
thereby isolating the firing chamber 36 from the inlet port 30 and the 
compressed gas source, as shown in FIG. 4. This isolation of the firing 
chamber 36 from the compressed gas source prevents compressed gas from 
flowing into the firing chamber to replace the air which has been 
discharged from the firing chamber in order to expel the projectile. This 
is of particular importance because the pressure in the regulator piston 
bore 62 has dropped resulting in the opening of the regulator valve 40. As 
shown in FIGS. 2 and 4-6, the on/off flow valve 76 is movable transversely 
relative to the longitudinal axis of the gun between the open and closed 
positions. In order to prevent compressed gas from leaking past the on/off 
flow valve when it is in the closed position, an o-ring seal 78 is 
provided adjacent the upper end of the flow valve chamber 56. In addition, 
a second o-ring seal 79 is provided adjacent the lower end of the flow 
valve chamber to prevent compressed gas from leaking out of the compressed 
gas delivery system. 
The air or firing chamber 36 supplies the compressed gas that expels the 
projectile through the barrel 22 when the firing system is in the firing 
mode. The air chamber 36 is defined by a bore formed in the main body 
portion of the gun 10 terminating at one end with an intermediate firing 
tube or power tube 80. An annular sleeve 82 interfits within the power 
tube 80 and, along with the power tube 80, defines a discharge path for 
compressed air contained in the firing chamber 36 to blast into a breech 
84 of the gun 10. The annular sleeve 82 includes a tapered portion 86 that 
further defines a passage for the blast of compressed gas. This tapered 
portion 86 on the power tube 80 is configured such that the air flows out 
of the air chamber 36 and the power tube at a controlled rate which 
prevents relatively fragile projectiles such as paint balls from breaking 
as a result of too much pressure building up behind the paint ball. 
Inasmuch as the pressure supplied to the firing chamber 36 has been 
substantially reduced from the maximum available pressure from the 
compressed gas source, the volume defined by the firing chamber 36 is 
substantially larger than found in many known arrangements. 
The blast of compressed gas exits the air chamber 52 upon actuation of a 
bolt assembly 88 which includes a power piston 90. The power piston 90 
comprises head and body sections 91 and 92, respectively, with the body 
section 92 being sized to fit within the annular sleeve 82 and power tube 
80. FIG. 2 best illustrates the remaining structural features of the bolt 
assembly 88, including a cylindrical actuating bolt 94 disposed in 
surrounding relation to the annular sleeve 82 and power tube 80. The 
actuating bolt 94 includes a protruding dog portion 95 disposed at one of 
its ends. A recoil spring 96 retracts the actuating bolt 94 against a 
bumper 97 when the actuating bolt 94 is returned to a ready-to-fire 
position. 
As described in detail in said U.S. Pat. No. 5,280,778, the bolt assembly 
88 is maintained in a ready-to-fire position with the use of a trigger 
mechanism which includes a sear 98 having an arm 99 that is rotatable 
about a pivot 100, which in a preferred embodiment comprises a threaded 
roller bearing axle. The arm 99 has a transversely extending actuating 
member 101 at one end, located on one side of pivot 100, and an 
interlocking element 104 at the other end, located on the other side of 
the pivot 100. The actuating member 102 is generally aligned with the 
on/off flow valve 74. The interlocking element 104 includes a notched 
portion that engages the dog portion 95 of the actuating bolt 94 in the 
ready-to-fire position. The interlocking element 104 preferably also 
includes an elongated portion extending substantially along the path of 
travel of the actuating bolt assembly 88 to provide a stop surface that 
prevents the actuating bolt assembly from engaging the interlocking 
element 104 during recoil of the actuating bolt assembly. 
An actuating lever 106 projects transversely on the side of the latch arm 
99 opposite the actuating member 102 and the interlocking element 104. A 
sliding trigger arm 108 disposed within the handle 16 operates to transmit 
force from the trigger 18 to the actuating lever 106. As explained in 
detail in said U.S. Pat. No. 5,280,778, this provides for semi-automatic 
firing of the gun 10 in operation. In the illustrated embodiment, the 
trigger arm 108 comprises a first link 110 which is pivotally connected to 
the actuating lever 106 and a second link 112 which is threaded into the 
first link. With this arrangement, any play in the trigger mechanism can 
be selectively adjusted merely by turning the second link 112 relative to 
the first link 110 and thereby thread the second link further out of or in 
to the first link. 
In accordance with another important feature of the present invention, the 
trigger mechanism may be configured such that a user's finger is "pushed 
back" after the gun 10 is fired through the execution of a pull stroke of 
the trigger 18. This provides the sensation of a "reactive trigger." The 
pushing back of the finger after the trigger 18 is actuated or pulled to 
fire the gun 10 helps the user pull the trigger in more rapid succession, 
thereby helping the user to achieve an increased firing rate. The trigger 
mechanism is operable to actuate the firing system from the ready-to-fire 
mode to the firing mode to fire the gun upon the execution of a pull 
stroke of the trigger 18 and from the firing mode back to the 
ready-to-fire mode to place the gun back in condition for firing upon the 
execution of a return stroke of the trigger 18. The pushing back of the 
user's finger after the gun is fired is accomplished by increasing the 
force applied through the trigger mechanism on the trigger 18, and counter 
to which the trigger must be pulled to fire the gun, immediately after the 
gun is fired. Since a lesser force is necessary to pull the trigger 18, 
this increase in the force opposing the trigger pull has a tendency to 
force the trigger 18 through the return stroke even if the user has not 
sufficiently released the trigger. Once the gun 10 is urged back in 
condition for another firing sequence, the force applied on the trigger 18 
through the trigger mechanism is reduced in order to enable the trigger to 
be manually pulled with greater ease. 
In the illustrated embodiment of the invention, an increased force applied 
on the trigger after the gun is fired is accomplished by configuring the 
on/off flow valve 74 with a differential piston head 114. The differential 
head 114 of the flow valve comprises a first portion 116 with a relatively 
larger effective surface area and a second portion 118 with a relatively 
smaller surface area. Thus, when the flow valve 74 is open, the system 
relies on the second portion 118 of the differential piston since as the 
effective area to which the pressure is applied. This results in a 
relatively smaller force being applied to the on/off flow valve 74 by the 
compressed gas in the system when the flow valve is moving to the closed 
position as compared to the force applied on the on/off flow valve 74 as 
it moves to the open position. As the differential piston head 114 is 
moved toward the O-ring seal 78, the system relies on the force applied to 
the lesser diameter portion 118 to provide resistance to the trigger pull. 
On the other hand, when the air chamber has expelled and the differential 
piston head 114 is in engagement with the upper O-ring seal 78, the force 
applied to the system is transferred to the larger first portion 116 of 
the piston head 114. At this point, the gas from flow chamber beneath the 
head 114 has expelled. Likewise, the regulator valve 40 opens and the 
system upstream from the on-off valve goes to the full line pressure of 
the compressed gas source. This slams the on-off valve back to the open 
position with greater force than applied to the valve when moved from the 
open position to the closed position. Once returned to the open position, 
i.e, when the larger diameter head 114 is disengaged from the O-ring seal 
78, the effective area of the on-off valve upon which the pressure acts is 
once again the smaller diameter piston head 116. 
Specifically, as the first step of the firing sequence, the trigger 18 is 
pulled and the resultant longitudinal movement of the trigger arm 108 acts 
to rotate the actuating lever element 106 of the sear in a clockwise 
direction (relative to FIGS. 2-6) which in turn rotates the sear arm 99 in 
the clockwise direction. As shown in FIG. 4, the rotation of the sear arm 
99 forces the on/off flow valve 74 into the closed position in response to 
the movement of the actuating member 102. This movement of the flow valve 
74 into the closed position is resisted by the downward force (relative to 
FIGS. 2-6) exerted on smaller second portion 118 of the differential 
piston head on the flow valve 74 by the compressed gas in the system. 
As shown in FIG. 5, once the on/off flow valve 74 has closed, the 
interlocking element 104 on the sear 98 releases the dog portion 95 of the 
actuating bolt and the compressed gas in the firing chamber 36 moves the 
power piston 90 rapidly forward and is released from the power tube 80 
resulting in the discharge of the projectile 20 from the barrel 22. Upon 
the release of the compressed gas in the firing chamber 36, the compressed 
gas in the regulator piston bore 62 is also released via the sensing line 
72 resulting in movement of the regulator valve 40 back into the open 
position. After the gun 10 has been fired, the gas pressure maintained in 
the system upstream from the on/off flow valve 74 continues to exert a 
downward force on the on/off flow valve. However, since all of the 
compressed gas downstream from the on/off flow valve 74 has been 
discharged, the effective area on which it acts is the larger first 
portion of the differential piston head. Thus, the force acting on the 
flow valve 74, and in turn on the trigger 18 through the sear 98, is 
increased immediately after the compressed gas is discharged from the 
firing chamber 36. Since the force now applied on the trigger 18 is 
greater than the force that had to be overcome to pull the trigger, this 
force tends to force a user to release the trigger 18 and allow the firing 
system to return to the ready-to-fire mode. In one preferred embodiment, 
it takes approximately 4 lbs. to pull the trigger and as soon as the gun 
is fired the force increases to 8 lbs. It has been found that this 
"reactive trigger" can enable a user to increase his or her firing rate by 
approximately thirty-three percent over conventional trigger arrangements. 
In addition, upon the release of the compressed gas in the firing chamber 
36, the recoil spring 96 drives the actuating bolt 94 rearwardly against 
the bumper 97 where it is held in place by the force of the recoil spring. 
The increased downward force exerted on the on/off flow valve 74 will 
force the trigger 18 through the return stroke. In particular, the force 
on the on/off flow valve 74 moves the actuating member 102 of the sear to 
effect slight counterclockwise rotation of the sear 98 to both open the 
on/off flow valve 74 and to latch the actuating bolt 94 with the 
interlocking element 104. The firing chamber is then recharged to the 
desired pressure via the compressed gas delivery system as described 
above. 
The differential between the force applied on the trigger 18 during the 
pull stoke and the force applied during the return stroke is further 
accentuated by the regulating system of the present invention. 
Particularly, as soon as the regulator valve 40 reopens because of the 
discharge of gas from the firing chamber 36, the pressure in the portion 
of the compressed gas delivery system upstream from the on/off flow valve 
74 increases from the regulated pressure to the full line pressure of the 
compressed gas source. This increase in the pressure results in a greater 
downward force being applied to the on/off flow valve 74. Of course, it 
will be appreciated that the advantages of the differential head on/off 
flow valve of the present invention could be achieved in firing systems 
which do not utilize the regulating system disclosed herein. Moreover, it 
will be appreciated that the teachings of the trigger mechanism of the 
present invention could also be applied to weapons other than the 
compressed gas powered gun disclosed herein. That is, the invention may be 
incorporated in any device actuated by hand manipulation with the use of a 
differential force transmission arrangement which is operable to apply a 
relatively greater force during a return stroke of the device than the 
force applied during the actuating stroke. 
While this invention has been described with an emphasis upon preferred 
embodiments, it will be obvious to those of ordinary skill in the art that 
variations of the preferred embodiments may be used and that it is 
intended that the invention may be practiced otherwise than as 
specifically described herein. Accordingly, this invention includes all 
modifications encompassed within the spirit and the scope of the invention 
as defined by the following claims.