Abstract:
A unitary plastic wad structure for use with a shotgun. The wad includes a shot cup portion and an obturating cup portion with both cups being of cylindrical configuration. The wad further includes a shock absorbing filler comprising transversely, obliquely, and longitudinally oriented planar members. The deflection characteristics of the transverse members provide the repeated attainment of a predictable shot pattern.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to plastic wads used in cartridges for shotguns. In particular, the invention relates to a one-piece wad structure having an obturating disc or cup which is connected to a shot cup by a filler comprising a shock absorbing structure having improved folding or structural deflection characteristics. 
     2. Description of the Prior Art 
     It is known to provide plastic wad structures for use in shotgun shells to (1) house the shot charge, (2) obturate combustion gases, and (3) cushion the shot charge when the loaded wad is fired from the gun. It is necessary to cushion the shot charge from the impact generated by the expanding power gases upon firing. This is necessary so that the shot will be gradually set in motion. This prevents undue deformation of the shot as well as lessening maximum pressure levels required in the shell to achieve a given shot load velocity. 
     It is also necessary that the filler or cushioning portion of the wad structure provide a cushioning action that is uniform in order to prevent any tilting or yawing of the shot cluster. 
     Attempts have been made in the prior art to provide wads with improved filler or cushioning structures. These attempts however have not been successful and are characterized by devices that are less than ideal since they exhibit a nonuniform, asymmetrical and uncontrolled deformation of the cushion members. This, in turn, prevents the attainment of a controllable and predictable shot pattern. 
     SUMMARY OF THE INVENTION 
     3. Object 
     An object of the invention is to provide a wad having an improved filler or cushioning structure. 
     A further object is to provide a wad having a filler or cushioning structure that exhibits a symmetrical and controllable deformation of its various elements to provide a predictable and controllable shot pattern. 
     Another object is to provide a wad which provides improved external ballistics of a fired shot column to improve the resultant shot pattern. 
     4. Summary Description 
     In accordance with the invention, I provide a one-piece wad having an obturating cup which is connected to a shot cup or protector by means of an improved filler element. The filler comprises a first plurality of planar elements oriented longitudinally to the wad and a pair of planar elements oriented transversely to the wad and interconnected with a pair of said plurality of longitudinally oriented elements. The filler further comprises a pair of obliquely oriented planar elements each having a first end connected to one end of each of said transversely oriented elements and having another end connected to one of said longitudinally oriented elements. The bottom of the shot cup is connected to a pair of the longitudinally oriented elements which, in turn, are connected to the pair of the transversely oriented elements. The downward force exerted by the shot load upon firing deflects the pairs of transverse elements and obliquely oriented elements downwardly in a uniform and symmetrical manner. This prevents undue deformation of the shot and also prevents a yawing or tilting of the wad and the shot load in the barrel upon firing. These factors provide for an improved, and predictable shot pattern. 
     5. Features 
     A feature of the invention is the provision of a filler structure comprising transversely, obliquely, and longitudinally oriented planar elements arranged to provide an improved cushioning effect for a shot load. 
     A further feature is that the cushioning effect is provided by a symmetrical deflection of the filler members so as to promote a predictable shot pattern. 
    
    
     DESCRIPTION OF THE DRAWING 
     These and other objects and features of the invention will be better understood from a reading of the following description of an exemplary embodiment of the invention taken in conjunction with the drawing in which: 
     FIG. 1 is an isometric view of a wad embodying the invention; 
     FIG. 2 is a longitudinal side sectional view of the wad of FIG. 1; 
     FIG. 3 is a bottom plan view of the wad of FIG. 1; 
     FIG. 4 is a front elevational view of the wad of FIG. 1; 
     FIG. 5 is a front longitudinal sectional view showing the deflectional characteristics of the filler structure; 
     FIG. 6 is an isometric view of the filler structure; 
     FIG. 7 illustrates a shotgun shell equipped with the wad of FIG. 1; and 
     FIG. 8 shows further deflectional characteristics of the filler. 
    
    
     DETAILED DESCRIPTION 
     A filler or cushioning structure 10 embodying my invention is shown on the drawing FIGURES as comprising an obturating cup 20, a shot cup 11, and a filler member generally indicated by the reference numeral 30 with the filler members including the elements designated 31 through 44 inclusive. The cut 20 comprises a top circular planar surface 21 whose circumference is connected to a downward projecting flexible internally tapered wall 22. Elements 21 and 22 together comprise an obturating powder chamber. 
     The shot cut 11 comprises a circular planar bottom member or surface 13 and an upwardly extending wall that is segmented longitudinally to the axis of the wad to define a plurality of sections or petals 12. The reception of the wad 10 in the shell 50 of FIG. 7 brings the petals 12 into close cylindrical adjacency for receiving the individual shot elements 51 of FIG. 7. 
     The filler 30 comprises a planar disc 34, generally parallel to and intermediate planar surface 13 and 21. Disc 34 is integrally connected on its bottom surface to surface 21 of cup 20 by means of a center strut 32 and by the two side struts 31 and 33. The surfaces of struts 31, 32, and 33 are longitudinally parallel to each other and are generally perpendicular to disc 34 and to the top surface 21 of cup 20. Centrally located on the inner surface of struts 31 and 33 are reinforcing triangles 31a and 33a. These triangles are integral to the struts 31 and 33, respectively, as well as to the top 21 of cup 20. 
     An important feature of the filler is that elements 34 and 21 together with the struts and triangles comprise a structure which is of light weight but yet is sufficiently resistant to distortion when subject to axial and radial forces. A further advantage is that the distance between the bottom of cup 20 and disc 34 is in excess of half of the diameter of elements 34 and 21. This presents a bearing surface to the interior of the shell case and shotgun bore which cannot tip or tilt and thus cannot become misaligned. 
     The top surface of disc 34 has integrally connected thereto the upwardly extending and longitudinally oriented planar struts 35 and 37 which may be considered to be extensions of struts 31 and 33, respectively. Center strut 36 also extends upwardly as an extension of strut 32. Each strut 35 and 37 generally projects upwardly one-half of the distance separating disc 34 and element 13. Struts 35 and 37 at their top end have integrally connected thereto an inwardly projecting transversely oriented and coplanar strut member 43 and 44, respectively. The length of each of struts 43 and 44 is generally equal to one-quarter of the distance between struts 35 and 37. 
     The top end of strut 36 is connected to the bottom of a &#34;V&#34; strut comprising the obliquely oriented elements 38 and 39 the upper ends of which are connected to the inner end of each of struts 43 and 44, respectively. Elements 38 and 39 each have a length generally equal to that of elements 43 or 44. Elements 34 and 21 and their connecting strut members form a geometrically symmetrical structure that is resistant to distortion by radial forces and yet is resilient to controlled axial forces. 
     The bottom 13 of cut 11 is integrally connected to a top end of longitudinally oriented planar struts 41 and 42 which project downwardly and connect at their bottom ends to the top surface of horizontal struts 43 and 44, respectively. Struts 41 and 42 are joined to struts 43 and 44, in close proximity to, but yet at a spaced apart distance from the intersection of each horizontal strut 43 and 44 with oblique struts 38 and 39, respectively. 
     FIG. 5 illustrates the configuration of the filler elements when the wad is partially compressed upon assembly in the shell. It should be noted that elements 13 and 34 and their connecting strut members are self aligning on their original longitudinal axis. Elements 13 and 34 remain parallel to each other under compression. Disc 34 is an integral part of the functionally solid bottom portion of the wad and is connected by the flexible strut members 43, 38, 39, and 44 to the shot cut. Thus when under compression, the entire wad remains an axially aligned structure. 
     On FIG. 5, the intermediate elements 38, 39, 43, and 44 permanently deformed prior to firing and therefore continue to exert a relatively constant pressure on the power and the shot elements. This contributes to a controlled burning rate of the powder. 
     FIG. 8 illustrates the flexed state of elements 38, 39, 43, and 44 upon firing. Surface 13 contacts the upper end of struts 35 and 37; the lower ends of struts 41 and 42 bear against disc 34. The entire filler structure at this time is a rigid solid that cannot be misaligned. 
     Triangular members 41a and 42a and member 40 (FIG. 4) contribute to the rigidity of struts 41 and 42. 
     FIG. 7 shows the wad 10 inserted into a shotgun shell 50 having a case 52, shot 51, primer 53, and powder 54 but before the loading force deforms the elements downwardly as shown in FIG. 5. 
     FIG. 6 shows in expanded detail the various elements comprising the filler portion of the disclosed wad minus the disc 34.