Abstract:
An improved shotgun design that includes at least two barrels, a trigger assembly that allows for individual simultaneous firing of each barrel, a single magazine with parallel ammunition wells that each feed one barrel, and a single slide mechanism that actuates the loading/unloading mechanism and resets the firing mechanism for discharge of subsequent rounds.

Description:
REFERENCE TO RELATED PROVISIONAL APPLICATION 
       [0001]    This application claims priority to provisional U.S. Application, Ser. No. 61/893,012, filed on Oct. 18, 2013, which is hereby incorporated by reference for all purposes. 
     
    
     BACKGROUND 
       [0002]    The present disclosure relates generally to shotguns. In particular, double-barrel pump shotguns are described. 
         [0003]    The Second Amendment to the United States Constitution guarantees American Citizens the right to bear arms. Firearms are a ubiquitous component of American culture and are used for many purposes, including hunting, recreational target shooting, home defense, and personal defense. Common types of firearms include handguns, rifles, assault rifles, and shotguns. Shotguns serve particularly vital peace keeping and defensive roles in law enforcement and military applications. 
         [0004]    Known shotguns are not entirely satisfactory for the range of applications in which they are employed. For example, existing shotguns offer limited ammunition capacity. Conventional shotguns are often limited to single round or double round capacities. Further, spent shell casings must be removed from a shotgun barrel prior to loading and firing subsequent rounds. 
         [0005]    In addition, although some conventional shotguns allow multi-round capacities, conventional shotguns are limited by maximum round capacity. Conventional multi-round capacities range from 2 rounds in a breach-load double-barrel shotgun to 32 rounds in a drum magazine shotgun. Drum magazines are often undesirable because the drum configuration is large and bulky. 
         [0006]    Typically, rounds in a handgun magazine or high-powered rifle magazine are stacked in a staggered configuration. In other words, two columns of rounds are stacked side-by-side inside the magazine. Staggering the rounds in a staggered magazine essentially doubles the capacity of a linear stack magazine of identical dimension. Handgun and rifle rounds incorporate pointed or rounded tips that allow the round to exit the staggered magazine at an angle and to self-guide into the gun barrel. 
         [0007]    Unlike handgun and rifle rounds that incorporate round or pointed tips, shotgun rounds are flat on the tip. Existing shotgun magazines have failed to incorporate a staggered configuration for existing shotgun rounds, primarily because the flat-tipped shotgun rounds cannot self-guide into the gun barrel. Thus, when flat-tipped shotgun rounds are pushed out of a staggered magazine, the flat-tipped rounds jam in the firing port causing the shotgun to malfunction. 
         [0008]    Therefore, maximum round capacities of existing shotguns are limited by existing magazine configurations. Further, total capacities of existing magazine configurations are limited due to weight distribution and dimension limitations. Existing shotgun magazine configurations include under-barrel tubes, single-stack magazines, and drum magazines. 
         [0009]    Conventional under-barrel tubes cannot extend past the shotgun barrel to which they are mated. Under-barrel tubes must not protrude past the exit port of the shotgun barrel because a protruding under-barrel tube would interfere with the trajectory of a round fired from the barrel. A longer under-barrel tube capable of holding more rounds would be awkward to maneuver and would inhibit the accuracy of the shotgun. Currently, a maximum round capacity of 4-16 rounds is feasible with conventional under-barrel tubes. 
         [0010]    Additionally, existing single-stack magazines capacities are limited by length. Existing single-stack magazines mount beneath or above the shotgun barrel and are linear. In other words, rounds of ammunition are stacked directly above or below additional rounds and fed into the firing chamber in a linear fashion. The length of existing single-stack magazines must be limited to maintain balance and maneuverability with existing shotguns. A maximum round capacity of 10 rounds is feasible with existing single-stack magazines. 
         [0011]    Moreover, conventional drum magazines are large, awkward, and fragile. Live rounds are configured in a coil inside conventional drum magazines. A traditional coil of live rounds feeds into the shotgun barrel through a firing chamber port. The coiled rounds require a large drum size to accommodate multiple rounds. Drum magazines are fragile and malfunction-prone. A maximum round capacity of 32 rounds is feasible with existing drum magazines. Although conventional drum magazines offer larger capacities, drum magazines are flawed due to the large size and unwieldy nature of the awkward drum. 
         [0012]    Thus, there exists a need for shotguns that improve upon and advance the design of known shotguns. Particularly, there exists a need for double-barrel pump shotguns that incorporate side-by-side, staggered-stack magazines with large multi-round capacities. Examples of new and useful double-barrel pump shotguns relevant to the needs existing in the field are discussed below. 
       SUMMARY 
       [0013]    The present disclosure is directed to an improved shotgun design. The improved shotgun includes at least two barrels, a trigger assembly that allows for individual or simultaneous firing of each barrel, a single magazine with parallel ammunition wells that each feed one barrel, and a single slide mechanism that actuates the loading/unloading mechanism and resets the firing mechanism for discharge of subsequent rounds. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a perspective view of a first example of a double-barrel pump shotgun. 
           [0015]      FIG. 2  is a top overall view of the double-barrel pump shotgun shown in  FIG. 1  depicting the shotgun disassembled. 
           [0016]      FIG. 3A  is a side cutaway view of the double-barrel pump shotgun shown in  FIG. 1  depicting a chain drive trigger mechanism inside a lower receiver. 
           [0017]      FIG. 3B  is a top view of the double-barrel pump shotgun shown in  FIG. 1  depicting the chain drive trigger mechanism shown in  FIG. 3A  in its paired configuration, with one trigger mechanism for each barrel. 
           [0018]      FIGS. 4A and 4B  are perspective views of one of the bolts from the double-barrel pump shotgun shown in  FIG. 1 . 
           [0019]      FIG. 5  is a perspective view of the magazine from the double-barrel pump shotgun shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    The disclosed double-barrel pump shotguns will become better understood through review of the following detailed description in conjunction with the figures. The detailed description and figures provide merely examples of the various inventions described herein. Those skilled in the art will understand that the disclosed examples may be varied, modified, and altered without departing from the scope of the inventions described herein. Many variations are contemplated for different applications and design considerations; however, for the sake of brevity, each and every contemplated variation is not individually described in the following detailed description. 
         [0021]    Throughout the following detailed description, a variety of double-barrel pump shotgun examples are provided. Related features in the examples may be identical, similar, or dissimilar in different examples. For the sake of brevity, related features will not be redundantly explained in each example. Instead, the use of related feature names will cue the reader that the feature with a related feature name may be similar to the related feature in an example explained previously. Features specific to a given example will be described in that particular example. The reader should understand that a given feature need not be the same or similar to the specific portrayal of a related feature in any given figure or example. 
         [0022]    With reference to  FIG. 1  a first example of a double-barrel pump shotgun, double-barrel pump shotgun  100 , will now be described. Double-barrel pump shotgun  100  functions to dramatically increase the round capacity and effective firepower of existing shotguns. Additionally or alternatively, the 50-round magazine of double-barrel pump shotgun  100  can be loaded with #1 buckshot to facilitate or allow firing 800 thirty caliber projectiles down range in just over 20 seconds. Thus, the effective firepower of double-barrel pump shotgun  100  is greater than five M-60 machine guns firing concurrently in the same period of time. 
         [0023]    Double-barrel pump shotgun  100  addresses many of the shortcomings existing with conventional shotguns. For example, double-barrel pump shotgun  100  incorporates a staggered-stack, side-by-side magazine with a 50-round capacity. Moreover, shotgun  100  facilitates or allows feeding flat-tipped shotgun rounds from a staggered magazine and eliminates the shortcomings of conventional shotguns. 
         [0024]    By incorporating the staggered-stack, side-by-side magazine, shotgun  100  eliminates the magazine shortcomings of existing shotguns. The magazine of shotgun  100  mounts directly under the center of the receiver and eliminates any protrusion risk presented by conventional linear tube magazines. It offers significantly better capacity than a tubular magazine mounted underneath the barrel, which cannot exceed the barrel length, and cannot be removed to allow for quick swapping with a second, preloaded magazine. It offers a shorter length (in exchange for a slightly wider profile) compared with existing non-staggered linear magazines. Finally, compared to existing drum magazine designs, it offers greater mechanical robustness, resistance to adverse handling conditions, and a substantially slimmer profile. 
         [0025]    Moreover, the stack configuration of the new magazine ensures shotgun  100  is balanced and stable. Placing the magazine in the center of the receiver just in front of the trigger and grip facilitates or allows carrying and maneuvering shotgun  100  conveniently and easily. Additionally, centering the magazine between the grip and fore-grip distributes the weight of double-barrel pump shotgun  100  and eliminates trigger arm fatigue. 
         [0026]    As shown in  FIGS. 1-5 , double-barrel pump shotgun  100  includes an upper receiver  110 , a lower receiver  112 , an ejection port  114 , a trigger  120 , a first gear  121 , a second gear  122 , a first sprocket  123 , a second sprocket  124 , a grip  125 , a first chain  127 , a second chain  128 , a magazine  130 , a fore-grip  135 , operating rods  140 , a first bolt  143 , a second bolt  144 , a first rear sprocket  147 , a second rear sprocket  146 , a first rear gear  149 , a second rear gear  148 , a first barrel  150 , a second barrel  155 , a shroud  160 , an end cap  162 , a rear sight mount  170 , a plate  175 , a bolt stop  176 , and a butt stock  180 . 
         [0027]    As can be seen in  FIG. 1 , upper receiver  110  comprises the upper half of shotgun  100 . Upper receiver  110  is complimentarily configured with lower receiver  112  and cooperatively houses the internal mechanics of shotgun  100 . Ideally, upper receiver  110  is constructed from hardened  4140  tool steel. However, the upper receiver may be comprised of any now known or later developed material suitable for housing internal mechanics of firearms, including, but not limited to, wood, metal, plastic, glass-filled Nylon 66, Zytel®), carbon fiber, or composites. Upper receiver  110  includes ejection ports  114 . 
         [0028]    As shown in  FIGS. 1 and 2 , ejection ports  114  facilitate or allow bilaterally ejecting spent or fired shotgun shells from double-barrel pump shotgun  100 . In the  FIG. 1  example, ejection ports  114  are configured laterally. In other examples, the ejection ports may be arranged in any configuration that facilitates or allows safely and effectively ejecting spent shells. Acceptable ejection port configurations include, but are not limited to, vertical, acute angled, and obtuse angled. 
         [0029]    Lower receiver  112  comprises the lower half of shotgun  100 . Lower receiver  112  is complimentarily configured with upper receiver  110  and cooperatively houses the internal mechanics of double-barrel pump shotgun  100 . In the  FIG. 1  example, lower receiver  112  is comprised of 30-percent glass-filled Nylon 66, or Zytel® brand material. In other examples the lower receiver may be comprised of any now known or later developed material suitable for housing internal mechanics of firearms. Suitable lower receiver materials include, but are not limited to, wood, metal, plastic, carbon fiber, or composites. 
         [0030]    Upper receiver  110  and lower receiver  112  together combine to form the primary housing of shotgun  100 . Into this combined primary housing are inserted the first barrel  150 , second barrel  155 , magazine  130 , a trigger assembly comprised of trigger  120 , first gear  121 , second gear  122 , first sprocket  123 , second sprocket  124 , grip  125 , first chain  127 , and second chain  128 , first bolt  143 , and second bolt  144 , and bolt stop  176 . Butt stock  180  is attached to the outside of the combined primary housing, along with rear sight mount  170  and plate  175 . Operating rods  140  protrude into the combined primary housing and attach to the first bolt  143  and second bolt  144  to enable actuation of the bolts, comprising the action of the shotgun  100 . The workings of the action will be described further below. 
         [0031]    Also shown in  FIGS. 1 and 2 , grip  125  facilitates or allows controlling and manipulating shotgun  100 . Grip  125  is anatomically shaped to facilitate or allow gripping by a human hand. Additionally or alternatively, the grip may include grip elements to increase or improve user comfort. Examples of acceptable grip elements include, but are not limited to, rough or textured surfaces, rubberized surfaces, finger ridges, and palm indentions. Grip  125  is preferably constructed from either molded plastic, shaped or carved wood mounted to a metal or plastic frame, or plastic or metal coated with a cushioning rubber grip surface. Grip  125  may, however, be constructed from any material suitably strong to withstand the forces generated by the recoil of the shotgun  100  during firing and during actuation of the action by sliding the fore-grip  135  fore and aft. Such materials include wood, metal, plastic, composites, or any suitably strong material now known or later developed. 
         [0032]    Further considering  FIG. 2 , shotgun  100  can be rapidly disassembled into its component parts without tools in under 30 seconds by pressing two levers. Disassembly begins by removing the butt stock  180  by removing the stock lock pin  210 , which is used to adjust the butt stock  180 , and sliding the butt stock  180  off. This exposes disassembly lever  220  on the back of the upper receiver  110 . By pressing down on the disassembly lever  220 , the top of the upper receiver  110 , plate  175  with the handle and rear sight mount  170 , along with the bolt guide rails, will slide to the rear and off. Bolt stop  176  is removed by lifting it out vertically. Next, the vertical fore-grip  135  under the barrel is unlocked with the thumb actuated lever on the side of the grip shown in  FIG. 2  and pulled to the rear. Both bolts  143  and  144  will drop free into the rear of the upper receiver  110 , and may be removed. Front disassembly lever  230 , located at the front of the barrels is then moved to the left, enabling removal of the block between the barrels, the slide action vertical fore-grip  135 , the vertical grip mount, the slide action rods  140 , and the barrel shroud  160 . 
         [0033]    Shotgun  100  can be reassembled by reversing the foregoing steps. In the example shown in  FIGS. 1-3B , trigger  120  is configured in two identical halves as a side-by-side double trigger. Pulling one side of trigger  120  in turn fires a live round from its associated barrel of the double-barrel pump shotgun  100 . By placing the two halves adjacent to each other, both sides of trigger  120  may be pulled simultaneously to fire a live round from both barrels simultaneously. The trigger  120  may alternatively be configured as a single trigger which fires one round from one barrel of the shotgun on a first pull, and one round from the second barrel of the shotgun on the second pull. In yet a further variation, the trigger  120  may be configured as a single trigger which fires both barrels of the double-barrel pump shotgun simultaneously. 
         [0034]      FIG. 3A  depicts the trigger and tire control mechanism for a single barrel and bolt. As shown most clearly in  FIG. 3A , pulling trigger  120  moves a slide bar  310  that makes contact with first rear gear  149 , which converts the sliding motion of the slide bar  310  into rotational motion. First rear gear  149  imparts rotational motion a first rear sprocket  147  via rear shaft  320 , to which both first rear gear  149  and first rear sprocket  147  are affixed. This rotational motion is concurrently imparted to a first sprocket  123  by way of a first chain  127 . First sprocket  123  imparts its rotational motion to first gear  121  via front shaft  330 , to which first sprocket  123  and first gear  121  are affixed. Finally, first gear  121  is in physical contact with the firing mechanism in first bolt  143 , actuating the mechanism and thereby firing a round of ammunition as trigger  120  is pulled. 
         [0035]    For triggers  120  implemented as two adjacent halves capable of firing each barrel independently, the foregoing trigger and tire control mechanism is duplicated in mirrored fashion for a second bolt  144  and barrel. In particular slide bar  310 , rear shaft  320 , and front shaft  330  (shown in  FIG. 3A  as second front shaft  340 ) all independently move as their corresponding trigger  120  is pulled. 
         [0036]    Turning to  FIG. 3B , an overhead view is provided of the two mirrored trigger and fire control mechanisms, showing the identical first rear gear  149  and second rear gear  148 , first rear sprocket  147  and second rear sprocket  146 , first chain  127  and second chain  128 , first sprocket  123  and second sprocket  124 , and first gear  121  and second gear  122 . Where trigger  120  is configured as a single trigger that fires both barrels simultaneously, the trigger and tire control mechanism will possess a single slide bar  310  that actuates a single rear gear  149 , which in turn is affixed to a single rear shaft  320 , to which are affixed first rear sprocket  147  and second rear sprocket  146 . The single bar  310 , rear gear  149 , and rear shaft  320  thus impart motion from the pulled trigger  120  simultaneously to both mirrored fire control mechanisms. 
         [0037]      FIGS. 4A and 4B  show the components of a bolt  400 , an example embodiment of first bolt  143  and second bolt  144 . Bolt  400  includes an extractor plate  410 , a control rod  420 , a locking pin  430 , firing pin  440 , and firing pin sear  450 . Extractor plate  410  catches upon a rim or groove built into the base of the case of a round of the appropriate ammunition, enabling the case to be extracted from the breech of the barrel associated with the bolt upon cycling the shotgun  100 &#39;s action. Control rod  420 , ideally located on the opposing side of the bolt  400  from the extractor plate  410 , engages with an internal cam within the bolt  400  for raising or lowering the locking pin  430 . Locking pin  430 , when raised, fixes the bolt  400  in position at the breach of its associated barrel when a round of ammunition is chambered in the barrel so as to ensure a secure firing of the round. The control rod  420  also extends from the bolt  400 , passes through the receiver housing the bolt  400  and attaches to the slide or fore-grip to enable cycling of the shotgun  100 &#39;s action. Bolt  400  is preferably comprised of 4140 steel or “tool steel.” Alternatively, bolt  400  may be comprised of any now known or later developed material that is suitable for containing the breech pressures and recoil forces experienced during the firing of a round of ammunition. Examples of suitable bolt materials may include, but are not limited to, aluminum, titanium, cobalt, tungsten carbide, wood, plastic, ceramic, carbon fiber, and composites. 
         [0038]    As described above in connection with  FIGS. 1 to 3B , first gear  121  and second gear  122  contact and activate the firing mechanism in first bolt  143  and second bolt  144 , respectively. Firing mechanism in example bolt  400  is comprised of the firing pin sear  450 , which pressure applied thereupon via the fire control mechanism gear trips the spring-loaded firing pin  440 , causing it to rapidly emerge from inside of bolt  400  and strike the primer of a round of ammunition, resulting in discharge of the shotgun  100 . The internal firing pin mechanism and ejector mechanism in bolt  400  are well known in the art, and thus will not be discussed in detail. Any now known or later developed firing mechanism and ejector mechanism may be incorporated in the bolts. An example firing cycle of double-barrel pump shotgun  100  will be discussed in detail below. 
         [0039]    In  FIG. 5 , the components of a magazine  500  are shown. Magazine  500  possesses a body  510  which is shaped to securely couple with lower receiver  112 , which is in turn equipped with a latching mechanism to retain an inserted magazine  500  until unlatched. Such latching mechanisms are well-known in the art. Magazine  500  is configured as a staggered-stack, side-by-side magazine. Two ammunition wells  520  are created by the insertion of a partition  530 , which splits the body  510  into the two ammunition wells  520 . Into each ammunition well  520  is inserted an ammunition follower  540  and spring  550 . The spring  550  contacts the follower  540  at one end, and the magazine bottom plate  560  at its opposite end. As ammunition is inserted into an ammunition well  520  it rests atop follower  540 , which is depressed down into the ammunition well  520  and simultaneously compresses spring  550 . Spring  550  thus imparts an increasing force against follower  540  and pushes the inserted ammunition to the mouth of the well  520 , in position for loading by the shotgun  100 &#39;s action. As discussed above, the staggered-stack magazine configuration is common in handguns and rifles. However, magazine  500  pairs two single staggered-stack magazines in a side-by-side configuration; each half of magazine  500  functions independently. Thus, magazine  500  facilitates or allows first barrel  150  and second barrel  155  to function independently. 
         [0040]    In the example embodiment, magazine  500  ideally has a maximum capacity of 50 rounds. Alternatively, the magazine may be configured to hold fewer or more rounds. Essentially, the overall length and total weight of the fully loaded magazine will be limiting factors when determining the maximum capacity of the magazine. The components of magazine  510  are ideally made of a material that is lightweight yet strong, such as aluminum, plastic, Nylon 66, Zytel®, a composite, or any other suitable material capable of securely and rigidly holding the weight of ammunition contained therein. 
         [0041]    As shown in  FIGS. 1-4B , first barrel  150  and second barrel  155  are inserted into upper receiver  110  and lower receiver  112 . The inner surface of upper receiver  110  and lower receiver  112  are tapered proximate first barrel  150  and second barrel  155  to facilitate or allow guiding rounds of ammunition exiting magazine  130  into first barrel  150  and into second barrel  155 . As a round of ammunition exits magazine  130  due to motion of the bolt towards the breech of its associated barrel, the combination of the extractor plate  410  and control rod  420  on each bolt act in concert to center a round of ammunition as it feeds from the magazine  130  on the bolt face, which in turn aligns the round of ammunition with the axis of the bolt&#39;s associated barrel. As the round of ammunition is further pushed forward by the bolt, it meets the aforementioned tapered inner surfaces of upper receiver  110  and lower receiver  112 . The combined effect of the extractor plate  410 , control rod  420 , and tapered inner surfaces acts as a funnel to guide the blunt front end of the round of ammunition into the breach end of the barrel, enabling smooth, consistent, and jam-free feeding. 
         [0042]    In the  FIGS. 1 and 2  example, first barrel  150  and second barrel  155  are comprised of steel. Specifically, the first and second barrels are comprised of 4140 steel or “tool steel.” Alternatively, the first barrel and the second barrel may be comprised of any now known or later developed material. Examples of suitable barrel materials include, but are not limited to, aluminum, titanium, cobalt, tungsten carbide, wood, plastic, ceramic, rubber, carbon fiber, composites, alone or in suitable combinations as appropriate to the materials employed. 
         [0043]    As shown in  FIGS. 1 and 2 , operating rods  140  pass through lower receiver  112 , connecting first bolt  143  and second bolt  144  with fore-grip  135 . Operating rods  140  facilitate or allow shotgun  100 &#39;s action to cycle between loaded and unloaded configurations. In other words, operating rods  140  cycle first bolt  143  and second bolt  144 . Fore-grip  135  facilitates or allows a user to control and manipulate shotgun  100 . Fore-grip  135  allows users to steady or aim the firing end of first barrel  150  and second barrel  155  and to pump or rack operating rods  140  to cycle first bolt  143  and second bolt  144 . 
         [0044]    In the  FIG. 1  example, fore-grip  135  is a below-barrel vertical fore-grip. Alternatively, the fore-grip may be configured in any shape or form that facilitates or allows aiming and cycling the double-barrel pump shotgun. Acceptable fore-grip configurations include, but are not limited to, in-line, side-barrel horizontal, and above-barrel vertical. The fore-grip may also include elements to increase or improve user comfort. Examples of acceptable fore-grip elements include but are not limited to rough or textured surfaces, rubberized surfaces, finger ridges, and palm indentions. 
         [0045]    In the  FIG. 1  example, fore-grip  135  is comprised of 30-percent glass-filled Nylon 66, or Zytel®. In other examples, the fore-grip may be comprised of any now known or later developed material suitable for facilitating aiming and cycling the double-barrel pump shotgun. Suitable fore-grip materials include, but are not limited to, wood, metal, plastic, rubber, ceramic, carbon fiber, and composites. 
         [0046]    As shown in  FIGS. 1 and 2 , a shroud  160  surrounds or protects first barrel  150  and second barrel  155 . In the  FIG. 1  example, shroud  160  is comprised of 30-percent glass-filled Nylon 66, or Zytel®. In other examples the shroud may be comprised of any now known or later developed material suitable for protecting the barrels. Suitable shroud materials include, but are not limited to, wood, metal, plastic, rubber, ceramic, carbon fiber, and composites. Additionally, the shroud serves an aesthetic purpose and may be configured in any aesthetically pleasing shape or form. 
         [0047]    As shown most clearly in  FIG. 2 , end cap  162  is configured to cooperatively couple with shroud  160 , first barrel  150 , and second barrel  155 . In fact, end cap  162  locks or maintains shroud  160  around first barrel  150  and second barrel  155 . Moreover, end cap  162  acts as a stop to maintain fore-grip  135  and operating rods  140  in proper operating position (“racked”) when cycling double-barrel pump shotgun  100 . 
         [0048]    As shown in  FIGS. 1 and 2 , rear sight mount  170  mounts to upper receiver  110 . In the  FIG. 1  example, rear sight mount  170  is configured to facilitate or allow gripping by a human hand and allows mounting optical sighting elements. Alternatively, the sight mount may be configured with a peep sight or to accommodate any now known or later developed sighting element. 
         [0049]    As can be seen in  FIG. 2 , plate  175  is configured to mount rear sight mount  170  to upper receiver  110 . In the  FIG. 2  example, plate  175  is comprised of 30-percent glass-filled Nylon 66 or Zytel®. In other examples, the plate may be comprised of any now known or later developed material suitable for mounting the rear sight mount to the upper receiver. Suitable plate materials include, but are not limited to, wood, metal, plastic, rubber, ceramic, carbon fiber, and composites. 
         [0050]    As shown in  FIGS. 1 and 2 , butt stock  180  is cooperatively coupled with lower receiver  112 . Butt stock  180  is anatomically configured to accommodate a human shoulder. Moreover, butt stock  180  is adjustable to make shotgun  100  more comfortable for a user to use and easier to control. Butt stock  180  is comprised of 30-percent glass-filled Nylon 66, or Zytel®. In other examples the butt stock may be comprised of any now known or later developed material suitable for facilitating user comfort and control of the shotgun. Suitable butt stock materials include, but are not limited to, wood, metal, plastic, rubber, ceramic, carbon fiber, and composites. 
         [0051]    Many of the above components of double-barrel pump shotgun  100  are identical on opposite sides. In other words, many components on one-half of double-barrel pump shotgun  100  are a mirror image of the same components on the other one-half. It is also contemplated that single components of the double-barrel pump shotgun may be utilized to comprise a single-barrel pump shotgun. Indeed, a single staggered-stack magazine with 25-round capacity may be combined with other components listed above to comprise a robust, single-barrel pump shotgun with firepower and balance superior to existing pump shotguns. 
         [0052]    With reference to  FIGS. 1-5 , the tiring cycle of double-barrel pump shotgun  100  will now be described. First, with live rounds loaded in magazine  130 , magazine  130  is inserted in lower receiver  112 . Racking fore-grip  135  from a first position distal lower receiver  112  to a stop position proximate lower receiver  112  also moves the attached operating rods  140 . Concurrently, operating rods  140  cycle the attached first bolt  143  and second bolt  144 . As the fore-grip  135  is moved rearward towards the lower receiver  112 , the operating rods  140  first extend into their associated bolts, actuating their internal cams which in turn lowers the associated locking pins. This frees the bolts to be moved rearward by the operating rods  140 , as they continue to travel rearward with the fore-grip  135 . When fore-grip  135  reaches its rear-most stop position, first bolt  143  and second bolt  144  simultaneously eject any spent shell casings from the firing chamber out of ejection ports  114 . 
         [0053]    Next, the fore-grip  135  is moved back away from lower receiver  112  towards its forward stop. This in turn causes the operating rods  140  to pull first bolt  143  and second bolt  144  back towards the breach of each associated barrel. First bolt  143  and second bolt  144  simultaneously strip new, live rounds out of magazine  130  into first barrel  150  and second barrel  155 , respectively. As the new rounds slide forward, they are pushed up by a combination of the magazine followers  540  and associated springs  550 , and the tapered shape of the lower receiver  112 . The rounds come into contact with their respective bolts&#39; extractor plate  410  and the control rod opposing the extractor plate  410 , which in combination serve to center the new rounds in line with the axis of each bolt&#39;s respective barrel, thereby ensuring smooth and accurate feeding of the new round. As fore-grip  135  is returned to the first position, first bolt  143  and second bolt  144  simultaneously complete loading the live rounds into first barrel  150  and second barrel  155 , and cock the firing mechanism in each bolt. Following making contact with breaches of their respective barrels, final forward travel of the fore-grip  135  actuates the cam inside each bolt, which causes each bolt&#39;s respective locking pin to raise, thereby securing the bolts from rearward movement and making the shotgun  100  ready to fire. 
         [0054]    A user may discharge the shotgun  100  by electing to pull one half of trigger  120  initially then the other half of trigger  120  subsequently, or both halves of trigger  120  simultaneously. Pulling trigger  120  fires rounds from first barrel  150  and second barrel  155 . Following firing, cycling of fore-grip  135  as described in the foregoing repeats the above extraction, ejection, and loading cycle, rendering double-barrel pump shotgun  100  again capable of firing two new live rounds. This cycle may be repeated sequentially until all rounds in the magazine have been fired. 
         [0055]    The disclosure above encompasses multiple distinct inventions with independent utility. While each of these inventions has been disclosed in a particular form, the specific embodiments disclosed and illustrated above are not to be considered in a limiting sense as numerous variations are possible. The subject matter of the inventions includes all novel and non-obvious combinations and subcombinations of the various elements, features, functions and/or properties disclosed above and inherent to those skilled in the art pertaining to such inventions. Where the disclosure or subsequently filed claims recite “a” element, “a first” element, or any such equivalent term, the disclosure or claims should be understood to incorporate one or more such elements, neither requiring nor excluding two or more such elements. 
         [0056]    Applicant(s) reserves the right to submit claims directed to combinations and subcombinations of the disclosed inventions that are believed to be novel and non-obvious. Inventions embodied in other combinations and subcombinations of features, functions, elements and/or properties may be claimed through amendment of those claims or presentation of new claims in the present application or in a related application. Such amended or new claims, whether they are directed to the same invention or a different invention and whether they are different, broader, narrower or equal in scope to the original claims, are to be considered within the subject matter of the inventions described herein.