Abstract:
A collapsible buttstock which is adapted primarily for use with military and tactical carbines, is supported by an extension tube which is connectable to the receiver of a carbine on which the collapsible buttstock is to be mounted. A storage enclosure is formed in the body of the buttstock and is sized and dimensioned so that it can receive a clip or magazine, typically able to carry 20 rounds, that is usable with the carbine on which the collapsible buttstock is mounted. The enclosure is provided with an openable cover that is hingably attached to the buttstock body. An easily operable cover latch assembly is usable to secure the cover in a closed position while facilitating expeditious opening of the cover to afford access to the spare magazine storage enclosure.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This U.S. utility patent application claims priority from U.S. provisional patent application No. 60/799,337, filed May 11, 2006, the entire disclosure of which is expressly incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention is directed generally to a collapsible carbine stock with a storage interior. More specifically, the present invention is directed to a collapsible carbine stock that is provided with a spare magazine storage enclosure. Most particularly, the subject invention is directed to a collapsible carbine stock with a spare magazine storage compartment having a closable cover. The carbine has a collapsible buttstock that can be positioned in a selected one of a plurality of positions to accommodate to the physical characteristics of the individual user. The buttstock has a storage compartment which is sized to accommodate a typical 20 round clip. The storage compartment in the collapsible buttstock is provided with a closable cover which may be at least partially transparent for easy visual confirmation that a filled spare clip is situated in the storage enclosure or compartment.  
       BACKGROUND OF THE INVENTION  
       [0003]     Military service or tactical carbines, such as the CAR-15 or the M4 are generally well known. These carbines are provided in a generally standardized configuration which is intended to allow a soldier or another user to carry and to use the carbine in typically harsh field conditions. In its standard configuration, the military service or tactical carbine includes a buttstock that is supported by an extension tube which includes a buffer assembly recoil spring. The stock may be slidable, with respect to the body or receiver of the carbine, to accommodate to the diverse physical characteristics of the various military and para-military forces who tend to use such carbines. Other than its ability to collapse, the buttstock of the generally known military service and tactical carbines do not provide any storage capability.  
         [0004]     In the M16 A2 or A1 stock, there is provided a small storage capacity. This is typically available for the storage of a cleaning rod which can be broken down into a plurality of sections, together with the customary cleaning attachments that one would expect to use with a cleaning rod. However, the standard buttstock of a military service or tactical carbine, such as the CAR-15 or M4 does not have such a storage cavity and thus cannot carry even the smallest of emergency supplies or a replacement clip of ammunition.  
         [0005]     It is often imperative that spare magazines be readily available. In combat situations, a soldier may be cut-off from a source of supply of clips of ammunition. Various stop-gap solutions to the problem have been proposed but none has proven to be particularly acceptable. Spare magazines have been taped together, either side-by-side or end-to-end or have been secured together through the use of clumsy “duplex” clamping devices. Such make-shift arrangements are clumsy, not particularly secure and prone to fail under strenuous usage. In an effort to overcome the obvious limitations of these efforts to carry spare clips or magazines, the users of those previous military service or tactical carbines have attempted to attach spare clips or magazines using a variety of straps or slings. Such efforts are generally fruitless.  
         [0006]     Spare magazines or clips are open at one end, so that the rounds can be stripped off the top and fed into the firing chamber. The only time that the open top of a clip or a magazine is not open is when the clip is actually loaded into the rifle or carbine. The spare clips or magazines are thus susceptible to entry of dirt and debris, particularly in combat or field environments. An attempt has been made to provide removable covers for such spare clips. However, if the cover is able to stay in place during the typical rough handling to which the clips or magazines are subjected, it is apt to be difficult to remove in a combat situation. Without such a cover, there is a potential for the dirt or debris which enters the clip to either jam the firing mechanism of the carbine or to cause other similar, potentially very dangerous malfunctions.  
         [0007]     It will be readily apparent that a need exists for a collapsible buttstock, usable with a military service or tactical weapon, that overcomes the limitations of the prior art. The collapsible carbine stock, with a spare magazine storage enclosure, in accordance with the subject invention, overcomes the limitations of the prior art.  
       SUMMARY OF THE INVENTION  
       [0008]     It is an object of the present invention to provide a collapsible carbine stock with a storage enclosure.  
         [0009]     Another object of the present invention is to provide a collapsible carbine stock with a magazine storage compartment.  
         [0010]     A further object of the present invention is to provide a collapsible carbine stock with a spare magazine storage enclosure that includes a securable cover.  
         [0011]     Still another object of the present invention is to provide a collapsible carbine stock magazine storage compartment with a cover which is at least partially transparent.  
         [0012]     Even yet a further object of the present invention is to provide a collapsible carbine stock with a spare magazine storage compartment that is durable and which will not adversely affect the strength of the collapsible stock.  
         [0013]     As will be described in detail in the description of the preferred invention, which is set forth subsequently, the collapsible carbine stock with a spare magazine storage enclosure, in accordance with the present invention, is intended for use with a standard, magazine-fed military service or tactical carbine, such as CAR-15 or an M4. The collapsible stock of the present invention is adapted to engage a receiver of a generally well-known carbine and includes an extension tube assembly that is adapted to cooperate with a buffer assembly and a recoil spring to dampen recoil and to drive the carbine&#39;s bolt forwardly. The extension tube, in accordance with the subject invention, is provided with a flange or a key which is cooperatively receivable in a keyway or a channel in the hollow collapsible buttstock. That key or flange has several axially spaced, aligned through bores, each of which is sized to selectively receive a locking projection of a collapsible buttstock lock. The projection is receivable in a selected one of the axially spaced bores in the extension tube key or flange to facilitate a proper positioning of the collapsible buttstock to accommodate users of various sizes.  
         [0014]     The collapsible buttstock in accordance with the present invention includes a hollow buttstock body that provides a compartment or enclosure which is sized to receive and to store a 20 round clip or magazine. The buttstock includes the extension tube, which will receive a buffer assembly and a recoil spring, which extension tube is adapted for connection with a typical carbine&#39;s receiver. The buttstock body also has an upper comb surface, with a selected check rest height. The hollow interior of the buttstock body, defines a cavity, compartment or enclosure which is sufficiently large to receive a standard twenty (20) round magazine. The enclosure, compartment or hollow space, in the interior of the carbine buttstock, is provided with a removable, hinged cover that can be locked in a closed position. When it is unlatched, and opened, the cover will provide unrestricted access to the magazine enclosure or compartment. As the door is opened, the magazine or clip is exposed so that it can be easily grasped for removal and use. The cover for the compartment may be either partially or completely transparent so that visual verification of the presence of a clip or magazine in the enclosure, and its being provided with rounds, is easily accomplished.  
         [0015]     The collapsible carbine stock with the spare magazine storage enclosure in accordance with the present invention has very little adverse weight impact on the overall carbine. The buttstock is made of lightweight, durable materials and is structured to engage the conventional extension tube receiving fitting of the carbine&#39;s receiver. It is essentially the same, in overall configuration, as the conventional, collapsible buttstock that carbines, such as the M4, are typically supplied with.  
         [0016]     A planar butt plate is carried on the buttstock and is positioned so that it will engage the shoulder of a user of the carbine, in a generally conventional manner. That butt plate has an aperture which is configured cooperatively with the extension tube receiving passage in the buttstock, and includes the same shape of the keyway as is a part of that extension tube receiving passage. When the collapsible buttstock is in its fully collapsed position, the distal end of the extension tube is situated in the aperture in the butt plate. That positioning will impart additional structural rigidity to the buttstock assembly which, as is known to those familiar with these weapons, is often called upon to perform tasks other than engaging the shoulder of the carbine&#39;s user.  
         [0017]     The extendible or collapsible buttstock of the present invention is positionable in a plurality of positions which correspond to a length of pull of the carbine&#39;s user. A collapsible buttstock lock extends transversely through the collapsible buttstock and has a locking projection at one end. That locking projection is selectively receivable in one of a plurality of cooperatively shaped bores which are spaced axially along the key that depends downwardly from the extension tube. On its end opposite to the locking projection, the collapsible buttstock lock carries a depressible locking button. The locking pin is biased to its locked position by a spring that is acting against an inner surface of the locking button. Actuation of the spring-biased collapsible buttstock lock, during adjustment of the length of pull of the collapsible buttstock is familiar to users of these types of carbines. That action is essentially the same as one which is utilized to release a magazine or clip from the receiver portion of the carbine.  
         [0018]     In a service carbine, such as the M4, the magazine is held in place by a spring-biased lock. When a user of the carbine inserts a magazine into the operative position in the magazine well, the spring-actuated lock holds it in place. To release the lock mechanism that holds the magazine in the magazine well, the carbine&#39;s user depresses a button to overcome the spring force of the magazine lock. To vary the length of pull of the collapsible buttstock, the user depresses a button against a spring force. Thus the provision of a spring-biased collapsible buttstock lock, for use in adjustment of the position of the collapsible buttstock of the subject invention provides a continuity of operation that will be familiar to the carbine&#39;s user.  
         [0019]     A spare magazine can be positioned within the pocket or receptacle in the collapsible buttstock and is retained in place by the provision of a hinged door that is secured by a latch mechanism including first and second spring biased opposing latch pins. The opposing latch pins engage axially aligned pin receiving blind bores formed in the buttstock&#39;s body, to thus keep the hinged door closed. The latch mechanism also includes first and second transverse latch pin retraction levers each of which is provided with a contoured retraction lever button. Each of the opposing latch pins is rigidly connected to one of the transverse retraction levers which, in turn, each projects laterally to the exterior of the stock&#39;s door, so the contoured retraction lever buttons are situated side by side on the exterior of the buttstock. The buttstock&#39;s door includes co-linear spaced slots which are approximately one inch apart. Each slot has a length of approximately one quarter inch, and the latch mechanism&#39;s transverse latch pin retraction levers each pass through one of the slots. The contoured retraction lever button is carried on the distal transverse end of each such retraction lever in an orientation allowing the user to actuate the latch mechanism with one hand by urging the two spaced, contoured retraction lever buttons together, thereby compressing the latch mechanism&#39;s biasing spring and concurrently retracting the latch mechanism&#39;s opposing pins. The hinged door can then open, uncovering the magazine storage pocket.  
         [0020]     The collapsible carbine stock with a spare magazine storage enclosure, in accordance with the present invention, is, as was alluded to previously, strong, durable and able to withstand the rugged use to which it is likely to be subjected in typical military operations. It will withstand such rough usage as well as do conventional buttstocks, such rough usage extending to, but not limited to use of the buttstock as a battering ram, a pry bar, a defensive weapon and the like. The buttstock itself is preferably made of a fiber reinforced material commonly known as “PA66”. The door or cover can be made from this material as well or can be a transparent resin or the like. The extension tube is preferably made of steel or aluminum and carries a generally well-known standard buffer assembly and recoil spring inside. The various fillings will preferably be fabricated of high strength, non-corrosive materials.  
         [0021]     The collapsible carbine stock with spare magazine storage compartment, in accordance with the present invention, is a substantial advance over the prior art. It provides a collapsible buttstock, with a magazine storage compartment that has previously not been available. It is far superior to the presently available buttstocks. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]     A full and complete understanding of the collapsible carbine stock with a spare magazine storage enclosure, in accordance with the present invention, may be had by referring to the detailed description of the preferred embodiment, as set forth subsequently, and as illustrated in the accompanying drawings, in which:  
         [0023]      FIG. 1  is a schematic side elevation view of a generally conventional carbine;  
         [0024]      FIG. 2  is an exploded perspective view of a collapsible buttstock in accordance with the present invention;  
         [0025]      FIG. 3  is a perspective view of an assembled buttstock of the present invention, with the magazine enclosure door open and supporting a clip or magazine;  
         [0026]      FIG. 4  is a perspective view, generally similar to  FIG. 3 , and showing the collapsible buttstock with the magazine enclosure door closed;  
         [0027]      FIG. 5  is a side elevation view of the collapsible buttstock;  
         [0028]      FIG. 6  is a cross-sectional view of the buttstock of  FIG. 5 , taken along line VI-VI of  FIG. 5 ;  
         [0029]      FIG. 7  is a cross-sectional view of the buttstock of  FIG. 5  taken along line VII-VII of  FIG. 5 ;  
         [0030]      FIG. 8  is a cross-sectional view of the buttstock of  FIG. 5  and taken along line VIII-VIII of  FIG. 5 ;  
         [0031]      FIG. 9  is an enlarged perspective view of the collapsible buttstock lock of the present invention;  
         [0032]      FIG. 10  is a rear elevation view of the collapsible buttstock of the present invention;  
         [0033]      FIG. 11  is a cross-sectional view of the collapsible buttstock and taken along line XI-XI of  FIG. 10 ;  
         [0034]      FIG. 12  is a side elevation view of the extension tube in accordance with the present invention;  
         [0035]      FIG. 13  is a bottom plan view of the extension tube;  
         [0036]      FIG. 14  is a cross-sectional view of the extension tube of the present invention and taken along line XIV-XIV of  FIG. 12 ; and  
         [0037]      FIG. 15  is a rear perspective view of the cover door in accordance with the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0038]     Referring initially to  FIG. 1 , there may be seen, generally at  20  a schematic depiction of a conventional M4 carbine with which the collapsible buttstock with a spare magazine storage enclosure, in accordance with the present invention, find use. The carbine  20  includes a barrel  22 , a receiver  24  and a shoulder engageable stock  26 . As is generally conventional, the stock  26  is attached to the receiver  24  by an extension tube  28  that includes a buffer assembly and a recoil spring which is not clearly visible in  FIG. 1 . The buffer assembly and recoil spring are well known generally and are utilized to absorb recoil, and to provide a source of power for the automatic or semi-automatic operation of the carbine, generally at  20 . It will be understood that the collapsible buttstock with a spare magazine storage compartment, in accordance with the present invention, is intended to be usable with a carbine, such as the M4 carbine depicted in  FIG. 1 . It will however also be understood that the collapsible buttstock with a spare magazine storage compartment, in accordance with the present invention, is also usable with other generally similar carbines and rifles, specifically those carbines and/or rifles that have an extension tube including a buffer assembly and a recoil spring.  
         [0039]     Turning now to  FIG. 2 , there may be seen generally at  30  a preferred embodiment of a collapsible buttstock with a spare magazine storage compartment in accordance with the present invention. The collapsible buttstock assembly  30  of the present invention includes a compartmented buttstock  32 , a cover door  34  for the compartmented buttstock  32 , an extension tube  36  on which the buttstock  32  is slidable between a collapsed position and a plurality of selectively adjustable pull length positions and a collapsible buttstock lock assembly, generally at  38  which functions, in a manner that will be described in detail shortly, to facilitate the deployment of the buttstock  32  between a collapsed position, similar to the one depicted for the stock  26  in  FIG. 1 ; i.e. with the stock  32  adjacent to the receiver  24 , and a fully extended portion, which is not specifically depicted but is one in which the length of pull has been maximized by increasing the separation between the buttstock  32  and the receiver  24  to the extent possible, while still supporting the stock on the extension tube.  
         [0040]     As may be seen in  FIG. 2 , the buttstock  32  is generally rectangular and includes a stock body  40  which is provided with a distal butt plate  42 . Butt plate  42  is generally planar although it may be slightly concave so that it will more comfortably engage a shoulder area of a person using a carbine or rifle that is equipped with the collapsible buttstock  30  of the present invention. The stock body  40  includes a bottom  44 , a sidewall  46 , as seen in  FIGS. 6 and 7 , a forward wall  48 , as seen in  FIG. 11 , and an upper comb surface  50 , which is generally arcuate, and which provides a check rest height. These several components of the stock body  40  cooperate to define a stock enclosure or receptacle, generally at  52 . A generally cylindrical extension tube receiving passage or bore  54 , which will be discussed in greater detail subsequently, overlies the stock enclosure  52  and is situated on the stock body  40  beneath the upper comb surface  50 , as may be seen in  FIG. 2 .  
         [0041]     The stock enclosure  52  is generally rectangular and is sized to occupy the bulk of the interior volume of the stock body  40 . Enclosure  52  is defined by an inner surface  56  of the butt plate  42 , by an inner surface  58  of the stock body sidewall  46 , by an upper surface  60  of the stock body bottom  44  and by an inner surface  62  of the stock body forward wall  48 . Since the primary purpose of the stock enclosure  58  is to receive a spare magazine or clip, typically one that carries 20 rounds, for use in the carbine of which the collapsible buttstock  32  in accordance with the present invention is intended to be used, it will be readily apparent that the overall size of the stock body  40  must be sufficiently large to have an enclosure  52  that will accept a replacement or spare 20 round clip or magazine.  
         [0042]     The stock enclosure  52  is generally rectangular, as depicted in  FIG. 2 . As discussed above, its size or volume must be sufficient to receive a spare or replacement clip or magazine for use with the carbine  20  to which the collapsible buttstock  30  of the present invention is to be attached. The representation of  FIG. 2  is to be understood to be illustrative of various overall shapes and appearances of the buttstock  32 . For example, the rear butt plate  42  is depicted as being generally planar with an overall ovoid shape. The butt plate  42  could be suitably contoured to enhance its compatible engagement with the shoulder of the user. The upper comb surface  50  is depicted as being a plain arcuate surface. It could be configured with an exterior contour or a pattern of checking or inletting that would make the comb surface more amendable to being engaged by the user&#39;s cheek. Similarly, the forward wall  48  of the stock body  40  could be provided with a surface contour that would facilitate grasping by the user. All of these surface embellishments and contours are not specifically depicted in the drawings of the subject invention. However, that is not to be construed as an indication that such elements are not available.  
         [0043]     The spare magazine receiving stock enclosure  52  is provided with a cover door, generally at  34 , as seen in  FIG. 2 . Cover door  34  has an overall shape that will complement the shape of the opening into the stock enclosure  52 . As depicted in  FIG. 2 , that overall shape of the cover door  34  is preferably generally rectangular. The cover door  34  is mounted in the stock body by a hinge mechanism that includes a hinge pin  64  which is receivable in a bore  66  in the butt plate  42  and which is aligned with a blind bore  68  in the stock body bottom  44 . A generally rectangular notch  70  is provided in the stock body bottom  44 . That notch  70  is sized to receive a hinge sleeve  72  which is formed on an inner lower surface of the cover door  34 , as may be seen in  FIGS. 6 and 15 . In use, the cover door  34  is placed in the buttstock enclosure  52  and is positioned so that a through bore  74  in the hinge sleeve  72  is aligned with the blind bores  66  in the stock body bottom  44 . The hinge pin  64  is then inserted into the aligned hinge sleeve through bore  74  and the stock body bottom blind bores  66 . If desired, an end of the hinge pin  64  and the butt plate bore  66  could be cooperatively threaded to retain the hinge pin  64  in place in the stock body  40 . The cover door  34  is now free to move between the open position depicted in  FIG. 3  and the closed position depicted in  FIG. 4 .  
         [0044]     A cover latch assembly is provided on the cover door and is indicated generally at  80  in  FIG. 2 . A pair of latch pins  82  are slidable in a latch pin passage  84  which is formed on a cover door latch tongue  86 . When the cover door  34  is attached to the buttstock body  40  by the hinge pin  64 , and the cover door  34  is placed into its closed position, the latch tongue  86  will be situated in a cooperatively shaped latch groove  88 , as seen in  FIGS. 2, 3  and  4 . The latch groove includes latch groove side walls  90 , a latch groove back wall  92  and a latch groove top wall  94 . As seen in  FIG. 6 , that latch groove top wall  94  is inclined or beveled and is complementary in shape to that of a latch tongue top wall  96 , which is seen most clearly in  FIG. 15 .  
         [0045]     Returning to  FIG. 2 , the two axially aligned cover door latch pins  82  are positionable in the cover door latch pin passage  86 . A cover door coil spring  98  is interposed between these two cover door latch pins  82 . If not retrained, the two cover door latch pins  82  would be forced out of the cover door latch pin passage  84  by the spring bias imparted to them by the cover door latch pin coil spring  98 . As seen in  FIG. 2 , each latch pin  82  has a transverse pin bore  100  at its inner end. These transverse pin bores  100  are sized to receive shanks  102  of latch pin retraction levers  104 . Each of these latch pin retraction levers  104  is slidable in a corresponding retraction lever slot  106  that is formed in the cover door latch tongue  86 . The two slots  106  extend in the axial direction of the latch pin passage  86 . Each of the latch pin retraction levers  104  has a transverse bore  108  which is preferably internally threaded. When the latch pins  82  are slid into the opposite ends of the latch pin passage  86 , sandwiching the latch pin coil spring  98 , they will be held in place by insertion of the retraction lever shanks through the slots  106  and into the transverse bores  100  at the inboard ends of the two latch pins  82 . The inboard ends of the two latch pins  82  also have threaded bores  110  that are essentially transverse to the retraction lever shank receiving bores  100 , also formed in the inboard ends of the latch pins  82 . A pair of set screws  112  are inserted through access bores  114  in the cover door latch tongue  86 . These set screws  112  are screwed into the threaded retraction lever bores  108  and into the threaded latch pin bores  110 , which are brought into alignment with each other. Now, the two latch pins  82  can be slid axially in opposition to each other by pinching the two latch pin retractor levers  104  between the user&#39;s thumb and forefinger.  
         [0046]     Each of the latch pin retraction levers has an enlarged head  116 . These heads are sized so that they will not fit into the two retraction lever slots  106 . To aid in the grasping and manipulation of the latch pin retraction levers  104 , each retraction lever head  116  may be provided with a retraction pin button  118 . These buttons  118  have central apertures  120  which are sized to fit over the enlarged heads  116  of the retraction levers  104 . Each such button  118  is preferably provided with a grip enhancing surface  122 . That surface can be a knurled or crosshatched or grooved surface.  
         [0047]     As is also depicted in  FIG. 2 , the latch groove side walls  90  are provided with latch pin receiving blind bores  124 . Once the cover door  34  has been secured in place in the opening of the buttstock enclosure  52 , by insertion of the hinge pin  64  through the aligned buttstock body bottom bores  68  and through the also aligned bore  74  in the cover door hinge sleeve  72 , the previously assembled cover door latch assembly  80  will be operable to hold the cover door  34  in its closed position. The two blind bores  124  in the side walls  90  of the cover door tongue receiving grooves  88  are located so that when the latch pins  82  extend out of the cover door tongue  86 , under the force exerted on them by the latch pin coil spring  98 , a front face  125  of the cover door  34  will be flush with the side of the buttstock body  40 .  
         [0048]     As is known in the art a generally conventional 20 cartridge magazine or clip  120 , as seen in  FIG. 3 , has a specific size. The interior volume of the buttstock enclosure  52 , and the dimensions of the enclosure opening and of the cover door  34  are such that the  20  cartridge magazine  120  can be placed into, and removed from the buttstock enclosure  52 . It is generally conventional to provide a view slot in the cartridge magazine. That view slot is provided so that the number of cartridges positioned in the clip  120  can be readily ascertained. As may be seen in  FIG. 15 , the cover door  34  may be provided with a transport view window  126 , that may be in the form of an insert in the body of the cover door  34 , or that could be molded integrally with the cover door. Alternately, the entire cover door  34  could be made of a transport material so that the presence of absence of a magazine or clip  120  could be readily verified, and so that the presence of cartridges in the magazine  120  could also be verified. The cover door view window  126  will be situated in the cover door  34  so that it will align with the view slot which is typically provided in a cartridge magazine  120 .  
         [0049]     The collapsible carbine buttstock with a spare magazine storage enclosure, in accordance with the present invention includes the extension tube, generally at  36 , as seen in  FIG. 2 . This extension tube is generally conventional, with respect to its primary purpose of supporting a buffer assembly and a recoil spring which are used to dampen the recoil of the weapon and to provide the force required to strip and eject a spent casing and to chamber a fresh round. The structure and function of the buffer assembly and of the recoil spring are well-known in the art, and do not form any part of the subject invention. As will be understood by those of skill in the art, the extension tube, generally at  36  in accordance with the present invention includes a threaded end  128 , which is preferably externally threaded and is adapted to be threaded into a milspec, internally threaded fitting, generally at  130  in  FIG. 1  which is situated at the rear of the receiver  24  of the M4 carbine depicted generally at  20  in  FIG. 1 .  
         [0050]     Returning to  FIG. 2 , the extension tube, generally at  36  has a cylindrically shaped extension tube body  132  which extends from the threaded end  128  to a closed end wall  134  at the opposite end of the tube body  132 . A flange, generally at  136  depends from the extension tube body  132  and is arranged offset laterally from a vertical center line  138  of the extension tube body  132 , as may be seen in  FIG. 14 . The extension tube flange  136  is aligned with an axial length of the extension tube body  132  and is not tangent with the extension tube body  132 , all as may be seen in  FIG. 14 . Flange  136  has a flange outer wall  140 , a flange inner wall  142  and a flange bottom wall  144 . As may be seen in detail in  FIGS. 12, 13  and  14 , the extension tube flange outer wall  140  includes a flange outer wall recess  146  which is formed with a plurality of axially spaced through bores  148 . As depicted in  FIG. 12 , there may be provided five such flange through bores  148 . These through bores  148  each has an inner abutment wall  150  that is defined by a portion of the hollow body  132  of the extension tube. The purpose and function of these extension tube flange through bores  148 , as well as the purpose and function of the extension tube body  132  and its flange  136  will now be discussed in detail.  
         [0051]     The buttstock body  40  is slidably or collapsibly supported on the extension tube, generally at  36 . As mentioned previously, the buttstock  40  includes an extension tube receiving passage or bore, generally at  54 . That bore has an overall configuration which is complementary to that of the overall shape of the extension tube  32 . The buttstock body extension tube receiving passage is generally cylindrical and includes a downwardly depending keyway  152 . That keyway  152  is defined by a keyway outer wall  154 , a keyway inner wall  156  and a keyway bottom wall  158 . The three keyway walls are complementary, in size and in shape, to the extension tube flange  136  which thus forms a key which is receivable in the keyway  152 . The buttstock body  40  is thus free to slide axially along the extension tube, onto which it is inserted. It is typically not rotatable with respect to the extension tube.  
         [0052]     Quite clearly, the buttstock body  40  cannot slide freely on the extension tube  36  during use of the carbine  20 . It is receivable in a selected one of a plurality of positions that can be selected in accordance with the physical characteristics of the user; i.e. the user&#39;s so-called pull length. Referring now initially to  FIG. 2 , the collapsible stock in accordance with the present invention includes a collapsible buttstock lock assembly, generally at  160 . This collapsible buttstock lock assembly, generally at  160 , includes a transversely slidable buttstock lock bolt, generally at  162 , a lock bolt biasing coil spring  164  and a collapsible buttstock lock release button  166 .  
         [0053]     The slidable lock bolt  162  has a slide shank  168  which, as may be seen in  FIG. 8 , is receivable in a transverse bore  170  that extends across the buttstock body  40  adjacent a juncture of the buttstock body forward wall  48  and an upper interior surface  172  of the buttstock magazine receiving enclosure  52 . As may be seen in  FIG. 8 , that transverse bore  170  has an inner shoulder  174  which acts as an abutment surface for a first end  176  of the biasing spring  164 . A button receiving recess  178  is formed in the buttstock body  40  and is concentric with the transverse bore  170 . It will be understood that the button receiving recess  178  is dimensioned to slidably receive the release button  166 . Preferably, that release button  166  has a central aperture  180  which is sized to receive a free end  182  of the bolt slide shank  168 . A second end  184  of the coil spring  164  abuts an inner surface of the button  166  to bias the slidable lock bolt to a locked portion, as will now be discussed.  
         [0054]     The slidable lock bolt  162  is depicted most clearly in  FIG. 9 . It includes the bolt slide shank  168 , with its free end  182 , as has been described above. At an end of the bolt slide shank  168 , opposite to the free end  182 , the slidable lock bolt, generally at  162 , is provided with a lock arm  186 . That lock arm  186  is attached, at a first end  188  to a second end  190  of the bolt slide shank  168 . At its second end  192 , the lock arm  186  is provided with a locking projection  194 . The locking projection is depicted as being generally cylindrical. It is sized to be receivable in a selected one of the several axially spaced flange through bores  148  which are distributed axially spaced along the flange outer wall  140  of the flange  136  of the extension tube  36 .  
         [0055]     Once the threaded end  128  of the extension tube  36  has been screwed into the milspec fitting  130 , which is a part of the receiver  24  of the carbine, generally at  20 , the collapsible buttstock body  40  can be slid onto the extension tube  36 . The key or flange  136  of the extension tube body  132  is received in the keyway  152  of the extension tube receiving passage  54  in the buttstock body  40 . During this process, the release button  166  is pushed into its cooperatively shaped button receiving recess  178  to slide the slidable lock bolt  162  to the left, as seen in  FIGS. 2 and 8 . The length of travel of the slidable lock bolt  162  is sufficient to allow the extension tube flange  136  to slide past the arm  186  and the locking projection  194  of the collapsible buttstock lock assembly  160 . Once the buttstock body  40  is positioned on the extension tube  36 , it can be slid along the tube  36  until it is positioned so that one of the axially spaced flange through bores  148  is aligned with the locking projection  194  of the slidable lock bolt  162 . If desired, the locking button  166  can be released once the buttstock body  40  has been slid onto the extension tube  36 . The locking projection  194  of the collapsible buttstock lock assembly will slide along the flange outer wall  140  until it drops into one of the axially spaced flange through bores  148 . If that position of the buttstock body  40  is not comfortable to the user, he can depress the button  166  to unseat the projection  194  out of a first through bore  148  and can slide the buttstock body  40  along the extension tube  36  until the projection  194  is aligned with a different one of the several spaced flange through bores  148 . It will be noted, as may be seen in  FIGS. 8, 12  and  14  that the inner abutment wall  150  of each of the through bores  148  will limit the amount of travel of the projection  194  into each of the through bores  148 . By proper dimensioning of the depths of the through bores  148 , the length of the bolt slide shank  168  and the length of the locking projection  194  it will be assured that, as depicted in  FIG. 8 , the exterior of the buttstock body  40  does not have any projections or protrusions which could cause the collapsible buttstock in accordance with the present invention to catch on the user&#39;s apparel or on other objects. A smooth overall profile of the collapsible buttstock in accordance with the present invention is thus assured.  
         [0056]     The collapsible carbine stock with a spare magazine storage enclosure, in accordance with the present invention, provides all of the positive attributes of a generally conventional collapsible buttstock. It also provides a magazine or clip storage compartment or enclosure that is not available in the presently available carbine buttstocks. The spare magazine storage enclosure of the collapsible buttstock of the present invention is readily accessed by the carbine&#39;s user, is sufficiently rugged and durable to withstand the typical rough usage that a military or tactical weapon is expected to encounter, and is provided with a cover that can be quickly opened to provide rapid access to the spare magazine which may be situated in the collapsible buttstock. The collapsible buttstock lock assembly of the collapsible carbine buttstock in accordance with the present invention, is robust, is easy to actuate, does not provide any surface that would create a snagging hazard and is generally much more satisfactory, in use, than are the prior collapsible buttstock assemblies.  
         [0057]     While a preferred embodiment of a collapsible carbine stock with a spare magazine storage enclosure, in accordance with the present invention, has been set forth fully and completely hereinabove, it will be apparent to one of skill in the art that various changes in, for example, the specific materials used for the buttstock, the particular carbine which it is adapted to be used with, the particular structure of the clip or magazine that can be inserted into the buttstock enclosure, and the like could be made without departing from the true spirit and scope of the present invention, which his accordingly to be limited only by the following claims.