Abstract:
A training firearm that provides a realistic recoil effect. The firearm, preferably a pistol, may be an actual firearm retrofitted with a self-contained “blow back” assembly. Usually, the pistol will include a laser device that emits a laser beam readable by a target system. The laser replaces live rounds, and the blow back assembly causes return of the slide to cycle in a manner similar to that caused by live ammunition in an unmodified weapon. The blow back assembly is driven by a disposable cartridge of compressed gas self-contained in the handle of the pistol. A valve integrated with the firing pin releases a burst of gas when the firing pin is impacted by the hammer. The gas pushes back the slide and recocks the hammer for the next “round.” This system provides law enforcement and military personnel a realistic tool to develop recoil management and target re-acquisition skills.

Description:
FIELD OF THE INVENTION 
   The present invention generally relates to training firearms and, more particularly, to training firearms that generate a realistic recoil effect without using live ammunition. 
   BACKGROUND OF THE INVENTION 
   Law enforcement officers and many military personnel are trained and retested regularly for appropriate and accurate use of firearms in the line of duty. Various training systems are available. In most of these training systems, the officer is exposed to a series of mock scenarios represented on movie screens. The officer must make instantaneous decisions regarding when, where and whom to shoot as he moves through the course. 
   The handguns used during these exercises are not loaded with live ammunition. Rather, in most of these systems, a laser device of some sort is installed in the barrel. When the trigger is pulled, a laser beam is emitted from the barrel instead of a bullet. The screens and targets have laser-sensitive screens so that, when the laser beam hits the screen, a “hit” is recorded usually in a computer system. In this way, the officer&#39;s performance can be recorded and reviewed later for evaluation. 
   To accurately train and test the officer&#39;s performance, it is important that the conditions in the training facility closely simulate field conditions where live ammunition is being fired. In particular, it is important to recreate as realistically as possible the way a loaded handgun operates, including the recoil force of the gun while firing repeatedly. However, if only a laser is used in the weapon, there is no reverse impact generated with the weapon is “fired.” This deprives the trainee of critical experience in recoil management and target re-acquisition. 
   The unrealistic feel of a laser-modified training firearm has led to attempts to provide a training firearm with realistic recoil. An authentic automatic or semi-automatic handgun cycles or re-cocks itself automatically after the first round is fired. As each round is fired, the explosive impact of the bullet not only propels the bullet out of the barrel but pushes the slide assembly back to recock the hammer. The firing chamber is simultaneously reloaded. Thus, the gun can be fired repeatedly until the magazine is emptied without ever having to pull back the slide assembly or manually cock the hammer. However, the recoil force is significant, and novice shooters will be distracted by it until they become accustomed to it. The trainee must learn to recover quickly from the impact of the recoil and immediately to realign the gun sight for the next shot. 
   Various methods have been employed to cause the laser-modified training weapons to provide simulated recoil. Some of these include the use of compressed gas, usually CO 2 . In some cases, the compressed gas is supplied by a portable tank carried on the officer&#39;s back. In others, the gas is stored in a remote tank and supplied to the firearm through a flexible conduit connected to the weapon. However, in both these systems, the weapon is unnaturally tethered. This substantially affects the way the officer carries himself and handles his weapon, and significantly detracts from the reality of the experience. 
   Another method in the prior art to simulate live fire in a handgun is an “air” bullet. This is a bullet casing loaded with compressed gas, which discharges and cycles the weapon when the gun is fired much like a live round. These air bullets function well enough but are expensive and must be used within a few minutes of air injection or they will lose their charge. In addition, the spent shells are not disposable; they are retrieved and recharged. 
   There is a need for a training firearm that utilizes a laser “firing” device and yet provides realistic recoil without encumbering the trainee with extra equipment. There is a need for a recoil system that can be retrofitted in a wide variety of actual firearms so that the training experience is as close as possible to field experience with the same type of firearm. There is a need for a training firearm with a recoil system powered by inexpensive, disposable compressed gas cylinders. There is a need for a training firearm which avoids clean up and recharging of spent shells. There is a need for a training firearm the looks, feels and operates like an actual firearm. There is a need for a training firearm that can be used inexpensively for dry firing experience. 
   SUMMARY OF THE INVENTION 
   The present invention comprises a training firearm comprising a receiver. A barrel is supported on the receiver, and a slide is slidably mounted relative to the barrel for bidirectional forward and rearward movement relative to the receiver. A firing pin is included behind the barrel. The firing pin is mounted for movement between a retracted position and a firing position. 
   Also included in the training firearm is a firing assembly. The firing assembly includes a driver movable between a cocked position and a firing position. In the firing position, the driver is adapted to impact the firing pin propulsively. In the cocked position, the driver is held in biased condition in preparation for release. The firing assembly further comprises a trigger adapted to release the driver. The slide is adapted to recock the driver when it moves bidirectionally. 
   Still further, the training firearm includes a blow back assembly interposed between the barrel and the firing pin. The blow back assembly comprises a tube defining an external pressure chamber, and a housing defining an internal pressure chamber. The housing is movably received in the tube and has a valve opening fluidly connecting the internal pressure chamber with external pressure chamber. A closure member is movable in the housing between an open position in which the valve opening is open and a closed position in which the valve opening is closed. The closure member is adapted to move in response to advancement of the firing pin. 
   A compartment is provided inside the firearm, the compartment being adapted to contain a compressed gas cartridge. The training firearm also has a conduit adapted to fluidly connect the internal pressure chamber to a compressed gas cartridge in the compartment. 
   Either the tube or the housing is fixed relative to either the receiver or the slide, and the other one of the tube and the housing is fixed relative to the other one of the receiver and the slide. Thus, when a compressed gas cartridge is installed in the compartment, activation of the trigger causes the slide to move rearwardly recocking the firearm. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side elevational view of a popular 9 mm semi-automatic pistol. 
       FIG. 2  is a side elevational view of a training pistol made in accordance with the present invention, illustrating how similar to the authentic weapon the inventive weapon is. 
       FIG. 3  is a side elevational, partly sectional and cutaway view of the pistol shown in FIG.  2 . 
       FIG. 4  is an enlarged partly sectional view of the valve housing of the blow back assembly. 
       FIGS. 5A and 5B  are enlarged, partly sectional, fragmented views of the pistol shown in  FIG. 2  illustrating the structure and operation of the blow back assembly. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   With reference now to the drawings in general and to  FIG. 1  in particular, there is shown therein a 9 mm semi-automatic pistol, specifically a 1999 5900 Series Smith &amp; Wesson. The pistol is designated generally by the reference numeral  10 . As the structure and function of this type of pistol is well known, it will not be described in detail herein. Generally, such a pistol  10  comprises a frame or receiver  12  which supports the other components. The other main components include a barrel  14 , a slide assembly  16 , a grip  18 , a trigger  20 , and a hammer  22 . A magazine  24  is received inside the handle  18 . 
   In use of the pistol  10 , the hammer  22  first is cocked either by retracting the slide  16  or manually pulling back on the hammer. Then, when the trigger  29  is pulled, it releases the hammer which impacts the firing pin, driving it forward. When the firing pin hits the primer on the back of the bullet cartridge, the propellant in the casing ignites, forcing the bullet out of the barrel and, at the same time, pushing the slide  16  back over the hammer  22  recocking it. Simultaneously, the empty casing is ejected, and a new round is moved up from the magazine  24  into the firing chamber. 
   Shown in  FIG. 2  is a training firearm constructed in accordance with a preferred embodiment of the present invention and designated generally by the reference numeral  30 . As the drawings illustrate, the appearance of the training firearm  30  is virtually identical to the actual weapon  10  it is intended to replace. Indeed, as will be described hereafter, in the preferred practice of this invention, an actual firearm is merely modified in accordance with this invention by retrofitting it with the blow back assembly. 
   While the present invention is illustrated as a Smith &amp; Wesson 9 millimeter pistol particularly popular with law enforcement, the present invention is not so limited. As will become apparent, the invention is easily adapted to a wide range of firearms, including other types of semi-automatic pistols (double and single action). In addition, gas-operated weapons, such as AR 15 type weapons, MP- 5 &#39;s and P-90&#39;s may be modified in accordance with this invention. Still further, pump shotguns, such as REM 870 pump riot guns, can be modified to incorporate the recoil system of this invention. 
   With reference now also to  FIG. 3 , the preferred training firearm  30  will be described in more detail. Like the original pistol, the training pistol  30  comprises a receiver  32  that forms the main structure of the weapon. A barrel  34  is supported on the receiver  32 , as in the authentic pistol. A slide  36  is slidably mounted on the receiver over the barrel  34  for bidirectional movement forwardly and rearwardly relative to the receiver  32 . 
   In this preferred training pistol  30 , there is a firing pin  38 , but it is substantially shorter than in the comparable, unmodified pistol. The firing pin  38  is mounted in the receiver for movement between a retracted position and a firing position, which will be explained in more detail below. 
   The pistol  30  also includes a firing assembly  40 , which may vary widely depending on the firearm. Generally, the firing assembly comprises a driver and a trigger. The driver is movable between a cocked position and firing position. In the firing position, the driver is adapted to impact the firing pin propulsively. That is, the driver is designed to impact the firing pin with sufficient force and speed to activate the primer in the bullet cartridge. In the cocked position, the driver is held in biased condition in preparation for release by the trigger. The trigger is adapted to release the driver when pulled or activated in the normal fashion by the operator of the weapon. Thus, provides a training firearm that looks, feels and functions like the unmodified firearm. 
   Where the firearm is a semi-automatic pistol, as shown and described herein, the firing assembly  40  comprising a hammer  42  and a trigger  44 , which function as the corresponding components do in the original weapon. Accordingly, no detailed description will be provided herein. Similarly, the slide  36  in this preferred embodiment is adapted to recock the hammer  42 , or other driver, when the slide is pushed back rearwardly either manually or automatically during repeated “firing” of the weapon. As used herein, “slide” denotes the corresponding component in any automatic or semi-automatic weapon, such as the bolt in a semi-automatic rifle. 
   The firearm  30  preferably comprises a handle  46  depending from the receiver  32 . 
   As mentioned above, training firearms typically are provided with a laser device of some sort that is interactive with other components in a larger system, such as a laser-sensitive screen and a computer for recording, analyzing and playing back the officer&#39;s performance on the course. To that end, the training pistol  30  of the present invention, preferably is equipped with a suitable laser assembly  50  in a known manner. This laser assembly  50  may take a variety of forms, depending on the particular training system employed. Some laser devices are activated by the vibration in the weapon when the trigger is pulled. Others utilize an electronic switch. For purposes of illustrating this training firearm, a laser with a simple mechanical switch  52  is shown. Activation of this switch may be accomplished by the blow black assembly, yet to be described. 
   Referring still to  FIG. 3 , the training firearm  30  is provided with a blow back assembly  60  interposed between the barrel  34  and the firing pin  38 . The blow back assembly  60  is adapted to cycle the slide  36  in response to activation of the trigger  44 , as in the unmodified weapon. Preferably, the blow back assembly  60  comprises a tube  62  that defines an external pressure chamber  64 . In the embodiment illustrated herein, the tube is fixed inside the rear of the slide  36 . More preferably, the tube  62  has a closed rear end  66  with a firing pin passage  68  therethrough. 
   When retrofitting an authentic pistol, a cylindrically shaped recess is reamed into the rear of the slide. A cylinder is fixed inside this recess with a suitable bedding compound, such as a two-part epoxy, although other fixation methods will be apparent. The firing pin is shortened to form the firing pin  38  with a forward end  70 . The firing pin  38  and passage  68  in the tube  62  are sized to permit reciprocal movement of the pin in the passage for a reason which will become apparent. It should be noted that, though the tube  62  is shown cylindrical in shape, this configuration is not essential and will vary with shape of other cooperating components. 
   Referring still to FIG.  3  and now also to  FIG. 4 , the blow back assembly  60  may also include a housing  72  defining an internal pressure chamber  74 . The housing  72  is sized to be movable, preferably telescopically movable, in the tube  62 . In the preferred form, the housing  72  has a first or front end  76  and a second or rear end  78 . A valve opening  80  is formed in the rear end  78 . The valve opening  80  fluidly connects the internal pressure chamber  74  in the housing  72  with the external pressure chamber  64  in the tube  62 . In this embodiment, where the tube  62  is fixed to the moving slide  36 , the housing  72  preferably is fixed relative to the receiver  32 , and more preferably is fixed to the barrel  34  and aligned therewith. To that end, the housing  72  is provided with external threads  82  on its front end  76  to mate with internal threads  84  ( FIGS. 5A and 5B ) on the breech end of the barrel  34 . 
   It will be apparent now that the preferred placement of the valve housing  72  is generally aligned between the firing pin  38  and the barrel  34  generally in the position of what would be the firing chamber in the unmodified pistol. It will also be appreciated that there are other ways to mount the housing  72  in this position. For example, the housing  72  could be fixed to the top of the gas cartridge frame  94 , eliminating the need to thread the barrel breech of the forward end of the housing. These and other configurations are contemplated by the present invention. 
   The housing  72  conveniently may be formed of brass tubing. Preferably, the rear end  78  of the housing  72  is formed of nylon, and may take the form of a firing pin breech plug that is threadedly received in the brass tubing. 
   With continuing reference to  FIG. 3 , the blow black assembly  60  includes a compartment contained somewhere within the weapon to contain a cartridge of compressed gas. The gas is used to drive the valve movement, as will be explained. Preferably, the cartridges to be used with the present invention are commercially available cartridges of 12 gm carbon dioxide (CO 2 ), such as the cartridge  90  show in FIG.  3 . These cartridges are widely available, inexpensive and disposable. Where the firearm is a hand gun or pistol with a grip, such as the handle  46 , the gas cartridge compartment may be advantageously placed inside the handle. When retrofitting an existing weapon, the magazine well provides an ideal compartment  92  for the gas cartridge  90 . A frame  94  of some sort for supporting the cartridge may be installed in the magazine well after the magazine is removed. The grip panels of the handle  46  may be perforated to prevent ice build-up around the cartridge  90 . 
   A conduit  98  is included to fluidly connect the internal chamber  74  in the housing  72  with the gas cartridge  90 . Preferably, the conduit  98  is flexible and will be rated at 1000 p.s.i. or higher. The firearm  30  may be provided with quick connect or push fittings  100  and  102  for attaching the conduit to the housing and the cartridge, respectively. The fitting  100  may be fixed as by welding to the housing  72  over a passage  104  in the wall of the housing. The fitting  102  may be affixed to the cartridge frame  94  for convenient connection to the cartridge as it is inserted in the compartment  92 . Where the housing  72  is fixed to the top of the cartridge frame  90 , the conduit could take the form of a passageway formed through a block of metal forming the upper portion of the frame  94 . 
   Referring still to  FIG. 4 , the blow back assembly  60  further comprises a closure member movable in the housing  72  between an open position and a closed position. In the open position, the valve opening  80  is open fluidly connecting the external pressure chamber  64  to the gas cartridge  90 . In the closed position, the valve opening  80  is closed. In addition, the closure member is adapted in some manner to move in response to advancement or forward movement of the firing pin  38 . 
   In the preferred embodiment, the closure member comprises a rod  110  movable between a rearward position, illustrated in  FIG. 1 , and a forward position, shown in FIG.  5 B. Preferably, the rod includes a rear portion  112  comprising a rear end  114  and an enlarged portion, such as the conical section  116 . The rear end  114  is sized to be extendable through the valve opening  80 , and the tapered or conical section  116  is sized to seat in and thereby obstruct the forward end of the valve opening  80 . Although the shape can vary, in this preferred embodiment a taper angle of 12 degrees per side, or 24 degrees included, works well. 
   Now it will be noted that the front end  70  of the firing pin  38  and the rear end  114  of the rod  110  are correspondingly formed so that forward movement of the firing pin causes the front end to impact the rear end of the rod, thereby pushing the rod forwardly towards the position shown in FIG.  5 B. This opens the valve opening  80  and allows a rush of pressurize gas therethough. The forward end  70  of the firing pin  38  may be provided with an annular seal or check valve, such as the O-ring  120 . This seal will seat in the firing pin passage  68  when the gas pushes the pin  38  and tube  62  rearwardly, as shown in FIG.  5 B. 
   As shown in  FIGS. 4 ,  5 A and  5 B, it is advantageous to bias the rod  110  in the rearward position to maintain it in a closed position keeping the valve opening closed. To that end, the blow back assembly  60  may include a coil spring  122  around the rod  110 . Thus, when the advancing firing pin  38  pushes the rod forward (FIG.  5 B), the spring  122  will compress. However, upon withdrawal of the firing pin  38 , the spring  122  pulls the rod  110  back into the resting or closed position, shown in FIG.  5 A. 
   As indicated above, where the laser assembly  50  is activated by a simple mechanical switch  52 , it is desirable to have the blow back assembly  60  activate this switch at the same time it is recycling the weapon. To this end, the rod  110  is provided with a forward end  124  sized and positioned to impact the switch  52  when the rod is in the forward or open position, as shown in FIG.  5 B. To support and align the forward end  124  of the rod  110 , the housing  72  may be equipped with a plug  126  threadedly received in the front end  76  of the housing. A compression spacer  128  may be included, immediately behind the plug  126  to contain the front end of the spring  122 . Seals, such as O-rings  130  and  132 , may be included. 
   Now that the preferred structure of the training firearm  30  has been described, its operation will be explained. To the trainee, the weapon  30  will operate the same as the original, unmodified weapon. Initially, the hammer  42  is cocked for the first shot. The weapon  30  is fired by pulling the trigger  44 . The trigger  44  releases the hammer  42 , which in turn impacts the firing pin  38 . The advancing firing pin  38  pushes forward the rear end  114  of the rod  110 , opening the valve opening  80  and advancing the forward end  124  of the rod to activate the laser switch  52 . Thus, simultaneously, the laser “shoots” and the gas forces back the slide  36  to recock the firearm, readying the weapon for next shot. The weapon will cycle every time the trigger is pulled until the gas supply in the cartridge  90  is spent. 
   The propulsive effect of the burst of gas through the valve assembly in the training pistol  30  closely simulates the feel of normal recoil in an actual weapon. However, all the components of this training weapon, including the source of compressed gas, are contained entirely within the weapon. Thus, the trainee is not encumbered by a back pack or tethered to a remote supply of gas. It is almost as easy to replace a spent gas cartridge in this training weapon as it is to replace a magazine in an actual weapon. No spent shells are expelled, which have to be retrieved and recharged. The gas cartridges used by the training firearm are so inexpensive that the modified weapon can be used for dry-firing exercises. Most importantly, the blow back assembly of this invention can be retro-fitted into an actual weapon of the same type that the trainee uses in the field. Thus, the training exercise precisely duplicates the look, feel and function of the actual weapon, including its true-to-life lock time, recoil and heft. 
   Changes can be made in the combination and arrangement of the various parts and elements described herein without departing from the spirit and scope of the invention as defined in the following claims.