Patent Document

ORIGIN OF THE INVENTION 
     The invention described herein was made in the performance of official duties by an employee of the Department of the Navy and may be manufactured, used, licensed by or for the Government for any governmental purpose without payment of any royalties thereon. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to buttstocks for attachment to firearms, and more particularly to a buttstock assembly that has removable storage tubes which can be sealed from the outside environment. 
     BACKGROUND OF THE INVENTION 
     For several military applications and/or operational groups, weapons may need to be collapsible for ease of transportation to a field venue, and then easily assembled in the field. For example, rifles are frequently designed to be collapsible. One typical portion of a collapsible rifle assembly is the buttstock that forms the aft-most part of the assembled rifle. In general, the buttstock must be ergonomic since the buttstock forms the interface with the user&#39;s shoulder area. Further, the buttstock can provide additional functionality such as a storage area since the buttstock does not generally contain any of the rifle&#39;s operating components. The storage area should provide a watertight and dirt-free environment. Still further, a good buttstock design should minimize the use of moving parts that can cause rattle noises, break, fall off, etc. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a buttstock assembly for a collapsible rifle. 
     Another object of the present invention is to provide a buttstock assembly having watertight and dirt-free storage areas. 
     Yet another object of the present invention is to provide an ergonomic buttstock assembly that is comfortable for a user over a range of shooting positions. 
     Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings. 
     In accordance with the present invention, a buttstock assembly for attachment to a rifle includes a buttstock that lo holds a plurality of removable and sealable tubes. In its simplest embodiment, the buttstock has i) a butt plate, ii) an elongated body extending perpendicularly away from the butt plate, and iii) a structural web coupled to the butt plate and elongated body. The elongated body defines a central cavity for receiving therein a portion of the rifle and further defines an elongated cavity on either side of and parallel to the central cavity. Each tube is open on one end thereof and forms a sliding fit with one elongated cavity. A cap is provided for sealing the open end of the tube. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of the buttstock assembly in accordance with an embodiment of the present invention; 
     FIG. 2 is an isolated side view of the buttstock portion of the assembly shown in FIG. 1; 
     FIG. 3 is an aft end view of the buttstock taken along line  3 — 3  of FIG. 1; 
     FIG. 4 is an isolated top view of the buttstock portion of the assembly taken along line  4 — 4  of FIG. 1; 
     FIG. 5 is an isolated side view of one of the tube&#39;s sealing caps; and 
     FIG. 6 is an exploded perspective view of the buttstock assembly in accordance with another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, and more particularly to FIG. 1, an embodiment of the buttstock assembly in accordance lo with the present invention is illustrated and referenced generally by numeral  10 . While buttstock assembly  10  will be described for its use with one of the U.S. Navy&#39;s M 16  collapsible-stock carbine-type weapons (e.g., the M 4 A 1  carbine), it is to be understood that the novel features thereof can be implemented in any buttstock assembly. 
     Buttstock assembly  10  has three separable components referred to herein as a buttstock  12 , a storage tube  14  (two of which are shown and can be used), and a tube cap  16  for sealing each tube  14 . In describing buttstock  12 , additional and simultaneous reference will be made to FIGS. 2-4 where side, aft end and top views, respectively, of just buttstock  12  are shown. 
     Buttstock  12  has a butt plate  120  forming the interface with a user&#39;s shoulder or, as in a later described embodiment, forming an attachment plate for a recoil pad. In the illustrated embodiment, butt plate  120  has ridges  121  formed therein along its aft face (illustrated in FIG. 3) to minimize slippage when buttstock  12  is pressed against a user&#39;s shoulder. 
     Extending perpendicular to and forward from butt plate  120  is the buttstock&#39;s body  122  which defines a plurality of longitudinal cavities along its length. At its central portion, body  122  defines a central cavity  123  for attachment to the aft end of a weapon which could be the weapon&#39;s receiver or, as in the case the M 16  carbines, a specially-provided tubular extension. Accordingly, the shape and size of cavity  123  will be dependent on the type of weapon to which the present invention will be joined. Typically, means are provided for securing the weapon to body  122 . In terms of the M 4 A 1  carbine rifle (not shown), its extension tube is inserted into central cavity  123 . One of several holes in the extension tube is aligned with a through hole  124  that passes vertically through buttstock  12 . The hole on the M 4 A 1 &#39;s extension tube that is aligned with hole  124  has a lockpin (not shown) passed therethrough to lock the rifle and buttstock  12  to one another. This method of attachment is well known in the art and is not a part of or a limiting feature of the present invention. The aft end of cavity  123  (visible in FIG. 3) can be open or partially open at  123 A to facilitate the cleaning of cavity  123  should it become dirty. 
     Disposed on either side of and parallel to cavity  123  are tube cavities  125 . Although not a requirement of the present invention, each of tube cavities  125  is identically sized and shaped to allow their usage with either of storage tubes  14 . Each of tube cavities  125  is fully open or accessible at the forward end thereof (visible in FIG. 1) and can be partially open or accessible at the aft end thereof (visible in FIG.  3 ). By making the aft end of each tube cavity  125  accessible, cleaning of the cavities is facilitated as is the removal of storage tubes  14  as will be explained further below. A tab  126  can be formed at the fully open end of each cavity  125  to retain tube  14  and its cap  16  as will be explained further below. 
     As best seen in FIG. 4, the width of body  122  can be such that it increases gradually at either side thereof starting at butt plate  120 . Specifically, the width of body  122  at its aft end is equal to that of butt plate  120  and then increases in a straightline angled fashion at  122 A to a constant width at  122 B. The ergonomic shaping of body  122  in this way allows the user to comfortably pivot buttstock  12  about butt plate  120  when butt plate  120  is pressed against a user&#39;s shoulder. 
     For structural rigidity of buttstock  12 , butt plate  120  and body  122  are coupled to one another by a structural web  127 . For a preferred construction of the present invention, buttstock  12  is molded from plastic (e.g., nylon) or cast in metal as a single unit so that web  127  is integral with butt plate  120  and body  122 . In addition to its structural function, web  127  can be used to provide the means to couple a rifle sling thereto. For example, slots  128 A and  128 B can be cut through web  127  to provide the user with a variety of options for threading a rifle sling therethrough. Slots  128 A and  128 B are oriented perpendicular to one another with slot  128 A being parallel and adjacent to body  122  and slot  128 B being parallel to and adjacent butt plate  120 . In addition to slots  128 A and  128 B, a plurality of circular holes  129 A and  129 B can be provided through web  127 . Holes  129 A and  129 B accommodate a standard sling swivel stud (not shown) to which the end of a rifle sling can be attached. 
     Referring again to FIG. 1, each of tubes  14  is identically sized and shaped for use with either of tube cavities  125 . Each tube  14  is open at one end  14 A and is sealed at its other end  14 B. The external size and shape of tube  14  is configured to slidingly engage the internal size and shape of tube cavity  125 . The internal size and shape of tube  14  is configured to accommodate the items (not shown) to be stored therein. In the illustrated example, cavity  125  and tube  14  are keyed or indexed to one another to prevent relative rotation therebetween. More specifically, tube  14  is cylindrically shaped in its longitudinal exterior except for a flat portion  14 C thereof that matches a flat portion  125 C of cavity  125 . The internal shape of tubes  14  can be cylindrical as shown. In the illustrated example, tubes  14  are made to fully fill cavity  125 . Accordingly, since body  122  tapers in width at its aft end as shown in FIG. 4, end  14 B of tube  14  must be correspondingly shaped to accommodate the tapering width of cavity  125  at its aft end. Note that this shaping of end  14 B can be eliminated if the length of tube  14  is such that it will not extend into the decreasing width portion of body  122 . Each tube  14  has its own sealing cap  16  which, when attached to tube  14 , should make tube  14  a watertight storage compartment. While a variety of sealing systems can be used, FIG. 5 illustrates an embodiment of cap  16  which utilizes two O-rings  160  and  161  supported on a cylindrical stem  162  that extends from an end plate  163 . A finger grip  164  extends from the opposite side of end plate  163 . End plate  163  incorporates a tab  163 A extending radially outward therefrom for reasons that will be explained below. 
     In operation, stem  162  of cap  16  is pressed into tube  14  until end plate  163  abuts open end  14 A. While O-rings  160  and  161  insure a snug and sealing fit with tube  14 , cap  16  can be rotated while in tube  14 . Tube  14  is then aligned with one of cavities  125  so that flat portions  14 C and  125 C match up. Tube  14  is then slid fully into cavity  125  and cap  16  is rotated until tab  163 A engages tab  126  of buttstock  12 . The procedures is simply reversed to remove and un-cap tube  14 . Note that if the aft end of tube cavities  125  is open, tubes  14  can be pushed therefrom if need be. 
     Referring now to FIG. 6, another embodiment of the present invention is shown and referenced generally by numeral  100 . Assembly  100  adds a recoil pad  20  to the components described above for assembly  10 . Accordingly, components common to each of assemblies  10  and  100  will be identified with the same reference numerals and will not be described again for assembly  100 . 
     Recoil pad  20  is added to provide a more ergonomic and comfortable interface with a user&#39;s shoulder as opposed to the rigid interface provided by butt plate  120 . In the illustrated embodiment, recoil pad  20  is constructed from a rigid (e.g., plastic) frame  22  having a plurality of attachment tabs  24  extending therefrom that will be used to attach recoil pad  20  to butt plate  120  without the use of any tools. Accordingly, mounting holes, such as  120 A are provided in butt plate  120  to accommodate attachment tabs  24 . The particular number and/or design of attachment tabs  26  and corresponding mounting holes are not limitations of the present invention. A plurality of holes  26  can be formed in frame  22 . A rubber pad  28  is over-molded onto frame  22  with the rubber therefrom filling each of holes  26  during the over-mold process to keep rubber pad  28  on frame  22 . 
     The advantages of the present invention are numerous. The butt stock assembly provides removable and interchangeable watertight storage tubes that are easily stored in and retained by the buttstock. Various ergonomic features (e.g., various sling position accommodation, the ability to pivot the butt stock comfortably on one&#39;s shoulder, etc.) will improve user satisfaction with the weapon to which the buttstock assembly is attached. The buttstock assembly further minimizes moving parts to reduce noise and breakage concerns. 
     Although the invention has been described relative to a specific embodiment thereof, there are numerous variations and modifications that will be readily apparent to those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described.

Technology Category: 2