Abstract:
A semi-infinitely-adjustable butt stock assembly. A butt stock is slidably affixed to a buffer stem. An over-center lock is attached to the butt stock adjacent to the buffer stem. The user can disengage the over-center lock from the buffer stem by rotating a lever thereby permitting the longitudinal position of the butt stock to be adjusted relative to the buffer plate. To secure the butt stock at the desired position, the user rotates the lever in the opposite direction causing the over-center lock to re-engage the buffer stem. A cheek rest overlaying the butt stock and biased forward with respect thereto is adjustable vertically with respect to the butt stock by manually moving the cheek rest aft, adjusting it vertically, and releasing the cheek rest.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to the provisional application bearing Ser. No. 61/013,486 filed Dec. 13, 2007 and the provisional application bearing Ser. No. 61/075,501 filed Jun. 25, 2008. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     REFERENCE TO A SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to rifle stocks in general and to butt stocks in particular. 
     The typical butt stock is a simple, rigid component extending from the back of the rifle and engaging the user&#39;s shoulder when the rifle is being used. The distance between a rifle&#39;s trigger and the aft-most portion of the butt stock is known in the art as the pull length. The pull length for a rifle having a typical, rigid butt stock is fixed. 
     A rifle having an adjustable pull length is preferable to one having a fixed pull length for a number of reasons. For example, when a rifle is used by more than one user, it is important for each user to be able to adjust the pull length as desired for comfort and accurate shooting. In addition, even if the rifle is used by a single user, depending on the manner in which the rifle is being used (standing v. prone) and whether the rifle is equipped with optics (e.g., a scope) or other aiming devices (e.g., a bipod), the user may need to adjust the pull length for optimal comfort and accuracy. 
     In addition to the length of the butt stock being adjustable, it is also important for the top portion of the butt stock, called the cheek rest, to be adjustable. The height of the cheek rest on a traditional rigid butt stock is fixed. Depending on the user and manner in which the rifle is being used, the fixed height of the cheek rest may be uncomfortable for the user or serve as an impediment to accurate shooting (i.e. inhibit the user from properly viewing the reticle). It would be advantageous, therefore, to be able to adjust the height of the cheek rest to maximize shooting accuracy and the user&#39;s comfort. 
     In addition to being adjustable, it is also important for a rifle butt stock to be simple and reliable, having a small number of parts, quickly and quietly adjustable, and very rugged. This is especially true for rifles used in combat. Rifles that are used in the prone position need to be especially rugged due to the fact that they are often slammed to the ground when the user is transitioning from a standing to a prone position and then used as support when the user is transitioning from the prone to the standing position. Accordingly, there remains a need for simple, reliable, and rugged butt stock that can be adjusted quickly, quietly, and easily. 
     It is also important for a butt stock be lightweight and easily disassembled for repair or cleaning. Rifles are often hand carried by a single individual for long distances over uneven terrain. In order to minimize the energy required to carry the rifle, it is important for the rifle to be as light as possible. It is also important for the rifle to be kept clean. A rifle exposed to grit, sand, and other particulate is more likely to jam or otherwise malfunction. Tools for disassembling a rifle are rarely available in the field, however, and thus the user must be able to break down the rifle without the assistance of specialized tools. Accordingly, there remains a need for a lightweight butt stock that can be easily broken down without the use of specialized tools for cleaning and maintenance. 
     SUMMARY OF THE INVENTION 
     According to its major aspects and briefly recited, the present invention is an adjustable butt stock assembly. The butt stock is made of a rugged, rigid material such as plastic, metal, fiberglass, or carbon fiber and has a cylindrical hole running therethrough in the fore to aft directions. On the aft end of the butt stock is a butt plate, also made of a rigid, durable material. The butt plate is securely fastened to the butt stock and engages the user&#39;s shoulder when the user aims and fires the rifle. 
     Fitting inside the butt stock and extending fore to aft therein is a substantially cylindrical buffer stem having a plurality of longitudinal grooves. The butt stock is not rigidly fixed to the buffer stem, which serves as the backbone of the assembly, but is free to move longitudinally thereon. The buffer stem is rigidly attached to a buffer plate, which acts as the interface between the butt stock assembly and the remainder of the rifle. The longitudinal grooves of the buffer stem permit debris that may accumulate within the butt stock to exit the butt stock. This reduces the likelihood that the buffer stem and butt stock will become jammed because of sand or grit therebetween. In addition to the longitudinal grooves, slots and holes can be made in the buffer stem to further reduce its weight. 
     In one embodiment of the present invention the buffer stem also has, on one side and spanning a portion of the buffer stem&#39;s length, a rack of transverse teeth. The rack spans a substantial portion of the length of the buffer stem but typically less than five (5) inches. Underneath the rack of teeth is a locking assembly. The locking assembly, made of a stiff, durable material such as aluminum or steel, is comprised of a toothed foot, and a four-member over-center lock. A lever can be added to make locking and unlocking the over-center lock easier. Although the teeth on the toothed foot are like those on the rack of the buffer stem, the toothed foot has far fewer teeth than does the rack. 
     The locking assembly is attached to the butt stock via the butt plate. The locking assembly has a “locked” and “unlocked” position and the user changes the position of the locking assembly using the lever. When in the “locked position,” the lever is stowed against the bottom of the butt stock and the toothed foot of the locking assembly is raised and engages the rack of teeth in the buffer stem, securing the locking assembly (as well as the butt stock and butt plate) with respect to the buffer stem (and remainder of the rifle). When in the “unlocked position,” the aft end of the lever is pivoted down and away from the butt stock, the toothed foot is pulled away from the rack of teeth, and the locking assembly (along with the butt stock and butt plate) is free to slide longitudinally on the buffer stem. Although this particular embodiment utilizes a rack of teeth and a toothed foot, the present invention is not limited to this arrangement. Any means of engagement between the foot and the buffer stem is acceptable (e.g. posts and blind holes, friction plates, etc.). 
     The four members comprising the over-center lock are a driving bracket, an oblong fork, a floating member, and an ankle. All four members have two pivot points at which other members of the lock are attached. (The ankle has a third pivot point at which the toothed foot is pivotally attached.) Each pivot point consists of a hole or a shaft or some other means of pivotal attachment. No more than two members attach at any given pivot point. 
     The oblong fork, which is rigidly attached to the butt plate and acts as the chassis upon which the other members are mounted, flexes when the lock is being “locked” or “unlocked” Mounting the oblong fork on the butt plate, which is typically made of a strong and stiff material such as aluminum or steel, provides a more sturdy and secure fastening point for the oblong fork (and therefore the lock) than if the oblong fork was mounted to the body of the butt stock, which is typically plastic. 
     The oblong fork has one short tine and, below that, one long tine. Both tines of the oblong fork have pivot points at their distal ends so that other lock members can be pivotally attached thereto. The driving bracket is pivotally attached to the long tine pivot. The ankle is pivotally attached to the short tine pivot. In addition to being pivotally attached to the oblong fork, the driving bracket and the ankle are also pivotally attached to the floating member. The point at which the driving bracket is attached to the floating member is the midpoint pivot. The point at which the driving bracket is attached to the floating member is the ankle driver pivot. 
     A line drawn from the long tine pivot to the ankle driver pivot is known as the threshold. When the over-center lock is “locked” or “unlocked,” the midpoint pivot crosses the threshold and the oblong fork flexes. When the midpoint pivot crosses the threshold, the oblong fork is more flexed than at any other time. When the over-center lock is in the “locked” position, the midpoint pivot is above the threshold, closer to the rack. When the over-center lock is in the “unlocked” position, the midpoint pivot is below the threshold and away from the rack. Importantly, when the midpoint is above the threshold (i.e. the lock is “locked” and the toothed foot is engaging the rack), the flexed oblong fork tends to push the midpoint up and toward the rack and away from the threshold. This ensures that the toothed foot remains engaged with the rack of teeth (i.e. that the lock assembly, when “locked,” stays “locked”). 
     To “unlock” the lock, the aft end of the lever is pulled down and away from the butt stock and the lever and driving bracket pivot about the long tine pivot. As the driving bracket pivots about the long tine pivot, the midpoint pivot crosses the threshold and rotates down and away from the rack. This pulls the floating member and ankle away from the rack as well, disengaging the toothed foot from the rack. The lock assembly, butt plate, and butt stock, are then free to slide as a single unit longitudinally over the buffer stem. 
     When the user has moved the lock, butt plate, and butt stock to the desired location (i.e. the optimal pull length has been achieved), the user then “locks” the lock. To “lock” the over-center lock, the user pulls the aft end of the lever up and toward the butt stock. This rotates the lever and driving bracket toward the rack. As the driving bracket rotates toward the rack, the midpoint pivot moves toward the threshold from below. As the midpoint pivot nears the threshold and the toothed foot engages the rack, the counterforce from the rack pushes the midpoint pivot away from the threshold. The user at this point must increase pressure on the lever to flex the oblong fork and force the midpoint pivot across the threshold. As the midpoint crosses the threshold, however, the now flexed oblong fork tends to push the midpoint pivot up and toward the rack, ensuring that the over-center lock stays in the “locked” position. 
     Because only a short range of motion (less than 90 degrees) is required to “lock” and “unlock” the over-center lock (i.e. pivoting the lever toward and away from the butt stock), the length of the butt stock assembly and, therefore, the pull length can be quickly and simply adjusted. Moreover, the butt stock is comprised of only four subassemblies that are held together with a single pin. The pin, which goes through the butt stock, lock assembly, and butt plate, is retained (i.e. not permitted to become fully detached from the butt stock) during disassembly to ensure that the butt stock assembly can be reassembled after cleaning or maintenance. In addition, because the over-center lock maintains a certain amount of internal tension within the butt stock assembly, the butt stock assembly is quiet and will not rattle when transported or shaken. 
     The present invention is also a butt stock with an adjustable cheek rest. Specifically, overlaying the top of the butt stock (and shaped substantially in conformity therewith) is a saddle-shaped rigid cheek rest, which can be adjusted up and down with respect to the butt stock. The cheek rest is biased in the forward direction by a spring-loaded biasing saddle and has vertical ridges on its interior surface dimensioned to cooperate with opposing vertical grooves in the biasing saddle. The interior sides of the cheek rest also have horizontal tabs dimensioned to cooperate with opposing horizontal posts and delta-shaped tabs in the sides of the butt stock. The horizontal tabs of the cheek rest and the posts and tabs of the butt stock are separated when the cheek rest is manually moved in the aft direction. When the horizontal tabs and ridges are separated, the cheek rest is free to be adjusted vertically. 
     Alternatively, the interior sides of the cheek rest can have detent channels that cooperate with the horizontal posts on the sides of the butt stock. The detent channels are “zig-zag” shaped and permit the cheek rest to be manually biased forward and aft and thereby adjusted vertically. When released, the biasing saddle ensures that the cheek rest remains engage with the horizontal posts of the butt stock. 
     These and other features and their advantages will be apparent to those skilled in the art of rifle making from a careful reading of the Detailed Description of Embodiments accompanied by the following drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       In the drawings, 
         FIG. 1  is a side view of a one embodiment of the present invention attached to a rifle receiver; 
         FIG. 2  is a perspective detail of one embodiment of the buffer assembly of the present invention; 
         FIG. 3  is an exploded perspective view of one embodiment of the lock assembly of the present invention; 
         FIG. 4  is a perspective view of one embodiment of the lock assembly in the locked position; 
         FIG. 5  is a perspective view of one embodiment of the lock assembly in the unlocked position; 
         FIG. 6A  is a cross-sectional view of one embodiment of the present invention when retracted and locked; 
         FIG. 6B  is a cross-sectional view of one embodiment of the present invention when retracted and unlocked; 
         FIG. 6C  is a cross-sectional view of one embodiment of the present invention when extended and locked; 
         FIG. 7  is a perspective detail of the butt stock of one embodiment of the present invention; 
         FIG. 8 ; is a perspective detail of the cheek rest of one embodiment of the present invention 
         FIG. 9  is a perspective detail of the biasing saddle of one embodiment of the present invention; 
         FIG. 10  is a perspective detail of the butt stock of an alternative embodiment of the present invention; 
         FIG. 11  is a perspective detail of the cheek rest of an alternative embodiment of the present invention; 
         FIG. 12  is a side view of an alternative embodiment of the present invention with the cheek rest rendered transparent; and 
         FIG. 13  is an exploded perspective view of the butt stock assembly of the present invention showing the four sub-assemblies. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is an adjustable butt stock assembly for use on a rifle. A side view of a preferred embodiment of the present invention  10  installed on a rifle receiver  8  is shown in  FIG. 1 . Attached to receiver  8  is buffer plate  18 . Buffer plate  18  serves as the interface between the butt stock assembly  10  and receiver  8  and is made of a very strong material such as steel or aluminum to provide a rigid, durable link between the butt stock assembly  10  and receiver  8 . Protruding aft from the buffer plate  18  is buffer stem  16 . Buffer stem  16  extends into butt stock  12 . Aft of butt stock  12  is butt plate  14 , which engages the user&#39;s shoulder when the rifle is being aimed or fired. The lock assembly  13  ( FIG. 3 ) enables the user to “lock” and “unlock” butt stock  12  from buffer stem  16  so that the butt stock can be extended or retracted (thereby adjusting the pull length of the rifle). A lever  26  can be added to the over-center lock to make “locking” and “unlocking” the over-center lock easier. 
       FIG. 2  is a detailed view of the buffer plate  18  and buffer stem  16 . Buffer stem  16  acts as the spine of the butt stock assembly  10  ( FIG. 1 ) and is made of a strong, stiff material such as aluminum, steel, or a composite polymer to support the other components of butt stock assembly  10  ( FIG. 1 ). Buffer stem  16  has several longitudinal grooves  17  that permit debris to exit butt stock  12  so that the debris does not prevent butt stock  12  from sliding smoothly over buffer stem  16 . Also, buffer stem  16  has a number of slots  19  therein to reduce its mass. On the bottom of buffer stem  16  is rack of teeth  22 . Rack  22 , while spanning a substantial portion of buffer stem  16 , is typically no more than five (5) inches long. 
       FIG. 3  shows an exploded perspective view of the lock assembly  13 . Lock assembly  13  is comprised of butt plate  14 , lever  26 , toothed foot  32 , and four-member, over-center lock  11 . Butt plate  14 , to which over-center lock  11  is mounted, is attached to butt stock  12  ( FIG. 13 ). Lever  26  can be used to “lock” and “unlock” over-center lock  11 , which causes toothed foot  32  to engage and disengage the rack of teeth  22  ( FIG. 2 ), as further explained below. The four members comprising over-center lock  11  are driving bracket  28 , oblong fork  29 , floating member  30 , and ankle  31 . Oblong fork  29  has a long tine  25  and a short tine  27 . Although roll pins  42  are shown connecting the lock members  28 ,  29 ,  30 , and  31  to one another and ankle  31  to toothed foot  32 , any means of pivotal connection would be appropriate. 
     The attachment between butt plate  14  and lock  11  must be very sturdy and rigid so that toothed foot  32 , which is attached to lock  11 , is able to firmly engage rack  22  ( FIG. 2 ). To achieve this rigid attachment, the aft end of the oblong fork  29  has a vertical flanged rail  33  that slides within a vertical receiving slot  35  in the butt plate  14 . To rigidly join the oblong fork  29  to the butt plate  14 , the flanged rail  33  is inserted into the receiving slot  35  and then a pin  70  is inserted into through-hole  37 , extending through one side of receiving slot  35 , through the flanged rail  33 , and then through the other side of receiving slot  35 . Connecting the lock assembly  13  to the butt plate  14 , which is typically made of aluminum or steel, as opposed to attaching it to butt stock  12 , which is typically made of plastic, provides the sturdy and secure connection required to ensure that toothed foot  32  positively contacts rack  22 . Butt plate  14  can also have a shoulder hook  21 , which can be folded out and placed on top of the user&#39;s shoulder when the user is firing the rifle. 
     The lock assembly  13  of  FIG. 3  is shown assembled and in the “locked” and “unlocked” positions in  FIGS. 4 and 5 , respectively.  FIGS. 4 and 5  also more plainly show the relative positions of the pivot points at which the members of over-center lock  11  are joined when the lock is in the “locked” and “unlocked” position. The pivot points of interest in terms of understanding the operation of over-center lock  11  are long tine pivot point  34 , midpoint pivot  36 , and ankle driver pivot  38 . Specifically, the relative position of the midpoint pivot  36  to a line drawn between long tine pivot  34  and ankle driver pivot  38  is of particular interest. This line is threshold  50 . 
     When over-center lock  11  is in the “locked” position as in  FIG. 4 , midpoint pivot  36  is slightly above threshold  50 . When over-center lock  11  is in the “unlocked” position as in  FIG. 5 , midpoint pivot  36  is below threshold  50 . Oblong fork  29 , which flexes when over-center lock  11  is “locked” or “unlocked,” tends to keep lock  11  in the “locked” or “unlocked” position, depending on whether midpoint pivot  36  is above or below threshold  50 , respectively. When midpoint pivot  36  is above threshold  50 , flexed oblong fork  29  tends to force midpoint pivot  36  higher, ensuring that over-center lock  11  stays “locked.” When midpoint pivot  36  is just below threshold  50 , flexed oblong fork  29  tends to force midpoint pivot  36  lower, ensuring that lock  11  remains “unlocked.” 
     Of course, the user can overcome the tendency imposed by the oblong fork  29  by manually rotating lever  26 . For example, when over-center lock  11  is in the “locked” position, as shown in  FIG. 4 , in order to “unlock” the lock, the user grabs the aft end of lever  26  and pulls it down thereby rotating driving bracket  28  about long tine pivot  34 . As the midpoint pivot  36  approaches threshold  50  from above, causing oblong fork  29  to flex slightly, the toothed shoe  32  is briefly forced even more firmly toward rack  22  ( FIGS. 1 and 2 ) and the user must apply more force to lever  26  to ensure that midpoint pivot  36  crosses threshold  50 . As soon as midpoint pivot  36  is below threshold  50  ( FIG. 5 ), flexed oblong fork  29  tends to force midpoint pivot  36  away from rack  22 . As midpoint pivot  36  is rotated below threshold  50  as seen in  FIG. 5 , floating member  30 , ankle  31 , and toothed shoe  32  are retracted and toothed shoe  32  disengages from rack  22  ( FIG. 2 ). Note that the user is required to rotate lever  26  far less than ninety (90) degrees to “unlock” over-center lock  11  and permit the pull length to be adjusted. This enables the user to adjust the pull length very quickly. 
     Once the lock is “unlocked” and the toothed foot  32  is disengaged from the rack  22 , the user is able to slide butt stock  12  (with butt plate  14  and lock assembly  13 ) along buffer stem  16  ( FIG. 2 ) to achieve the desired pull length. When the user has achieved the desired pull length, the user pulls the aft end of lever  26  up toward butt stock  12  ( FIG. 1 ). Referring now to  FIG. 5 , midpoint pivot  36  is below threshold  50  when the user begins to rotate lever  26  to “lock” over-center lock  11 . Accordingly, as midpoint  36  approaches threshold  50  from below, toothed foot  32  begins to bear on rack  22  ( FIGS. 1 and 2 ) requiring the user to apply even more pressure to lever  26  to flex oblong fork  29  and force midpoint pivot  36  across threshold  50 . Once midpoint pivot  36  crosses threshold  50 , the pressure on toothed foot  32  will tend to push midpoint pivot  36  even farther above threshold  50 , thus ensuring that the now “locked” over-center lock  11  stays “locked.” This tendency prevents lock  11  from inadvertently becoming “unlocked” as the rifle is being used. With toothed foot  32  firmly engaging rack  22 , butt stock  12  can no longer slide along buffer stem  16  and the rifle&#39;s pull length is fixed. 
     The same forces that ensure that over-center lock  11  stays “locked,” also ensure that the components of the over-center lock  11  are not loose with respect to one another. This prevents lock  11  from making undue noise when the rifle is being transported or repositioned. Likewise, the fact that the lock assembly  13  has so few parts makes the lock assembly  13  more reliable and reparable. 
       FIGS. 6A ,  6 B, and  6 C show one embodiment of the butt stock assembly of the present invention in the retracted and locked, retracted and unlocked, and extended and locked orientations, respectively. In  FIG. 6A , lever  26  is collapsed against the lock assembly  11  and the toothed foot  32  is engaged with rack of teeth  22 . With the toothed foot  32  and the rack of teeth  22  engaged, the butt stock  12  cannot move with respect to buffer stem  16 . Moreover, with the toothed foot  32  engaging the forward most portion of the rack of teeth  22 , the butt stock assembly  10  is in its most retracted orientation resulting in the shortest pull length. 
     In  FIG. 6B , lever  26  has been pivoted away from lock assembly  11  and the toothed foot  32  is disengaged from rack of teeth  22 . This permits butt stock  12  to be moved longitudinally with respect to buffer stem  16 .  FIG. 6C  shows one embodiment of the butt stock assembly  10  of the present invention with the butt stock  12  in the extended position with respect to buffer stem  16 . In  FIG. 6C , as in  FIG. 6A , the lever  26  is collapsed against lock assembly  11 . However, in  FIG. 6C , unlike  FIG. 6A , toothed foot  32  is engaged with the aft-most portion of the rack of teeth  22 . The butt stock assembly  10  is therefore in the most extended orientation resulting in the longest possible pull length. 
     The cheek rest of the present invention is vertically adjustable.  FIGS. 7 ,  8 , and  9  show the butt stock  12 , cheek rest  60 , and biasing saddle  74 , respectively, of one embodiment of the present invention.  FIG. 7  is a detail of butt stock  12  and shows delta traps  68  and butt stock posts  66 . These two features interact with delta tabs  64  and aft tabs  62  (shown on the inside of cheek rest  60  in  FIG. 8 ) to vertically secure cheek rest  60  with respect to butt stock  12 . Specifically, the delta traps  68  of butt stock  12  capture delta tabs  64  of cheek rest  60  and butt stock posts  66  of butt stock  12  slide between aft tabs  62  of cheek rest  60 . Moreover, the interaction between delta tabs  64  and delta traps  68  ensures that cheek rest  60  cannot move in the forward direction. 
     In order to adjust the height of cheek rest  60  with respect to butt stock  12 , the user simply pulls cheek rest  60  backward thereby releasing delta tabs  64  from delta traps  68  and butt stock posts  66  from aft tabs  62 , adjusts vertically cheek rest  60  to achieve the desired height with respect to butt stock  12 , and releases cheek rest  60 . Accordingly, in mere seconds and without any tools, the user is able to adjust cheek rest  60  to the desired height with respect to butt stock  12 . 
     Biasing saddle  74  ( FIG. 9 ), which is biased by spring  72 , ensures that delta tabs  64  remain in delta traps  68  and butt stock posts  66  remain in aft tabs  61 , thereby preventing cheek rest  60  from inadvertently moving vertically with respect to butt stock  12 . Specifically, biasing saddle  74 , which is longitudinally slidably attached to the top of butt stock  12  and vertically slidably attached to cheek rest  60 , biases cheek rest  60  in the forward direction. Biasing saddle  74  is longitudinally slidably attached to butt stock  12  by inserting flanged ridges  84  of butt stock  12  into T groove  78  of biasing saddle  74 . Biasing saddle  74  is vertically slidably attached to cheek rest  60  by inserting cheek rest ridges  80  into saddle slots  82 . Biasing saddle post  86  extends through post hole  88  in butt stock  12  ( FIG. 7 ). Spring  72  extends, which slides over biasing saddle post  86  extends into post hole  88  but is too large to extend all the way through butt stock  12 . 
       FIGS. 10 and 11  show an alternative embodiment of butt stock  12  and cheek rest  60 .  FIG. 10  shows an embodiment of butt stock  12  wherein the delta traps  68  of the first embodiment of butt stock  12  ( FIG. 7 ) have been replaced by another set of posts  67 .  FIG. 11  shows an embodiment of cheek rest  60  wherein the delta tabs  64  and aft tabs  62  of the first embodiment of cheek rest  60  ( FIG. 8 ) have been replaced by detent channels  63 . In this alternative embodiment, the posts  66  and  67  in butt stock  12  slide through detent channels  63 . As with the first embodiment, the biasing saddle  74  ( FIG. 9 ) biases the cheek rest  60  forward to keep posts  66  and  67  in aft portions  65  of detent channels  63 . To adjust the height of cheek rest  60 , the user simply pulls the cheek rest  60  aft with respect to the butt stock  12  and moves the cheek rest up or down to shift butt stock posts  66  and  67  to a new aft portion  65  of detent channels  63 . 
       FIG. 12  is a side view of the alternative embodiment of the butt stock  12  and cheek rest  60  wherein the cheek rest  60  has been rendered transparent for illustrative purposes.  FIG. 12  shows that posts  66  and  67  fit into and can slide within detent channels  63 . Cheek rest  60  can be removed from butt stock  12  entirely by moving cheek rest  60  back and forth with respect to butt stock  12  until posts  66  and  67  exit detent channels  63  at vertical exit channels  69 . Note that vertical exit slots  69  are slightly forward of the rest of detent channels  63 . Cheek rest  60 , which rides with biasing saddle  74  in the forward and aft directions, can only be adjusted sufficiently aft with respect to butt stock  12  and posts  66  and  67  when butt plate  14  is removed. This is because, when butt plate  14  is attached, biasing saddle post  86  ( FIG. 9 ), which extends aft through butt stock  12 , engages butt plate  14  and prevents the user from moving cheek rest  60  sufficiently aft to allow posts  66  and  67  to enter exit channels  69 . This prevents the user from inadvertently removing cheek rest  60  during adjustment. 
       FIG. 13  is an exploded view of one embodiment of the present invention showing the manner in which the entire butt stock assembly  10  can be disassembled into four subassemblies simply by removing a single pin  70 . To assemble the butt stock assembly  10 , the user simply inserts buffer stem  16  and butt plate  14  into the fore and aft ends of butt stock  12 , respectively. Then, the user inserts lock  11  into butt plate  14  and butt stock  12 . Pin  70  is then inserted in through-hole  37  to hold the subassemblies together. Note also that pin  70  is a retained pin. That is, pin  70  cannot be removed entirely from the butt stock assembly because it is equipped with a retaining ring (not shown) that is too large to exit through-hole  37  of butt stock  12 . 
     It is intended that the scope of the present invention include all modifications that incorporate its principal design features, and that the scope and limitations of the present invention are to be determined by the scope of the appended claims and their equivalents. It also should be understood, therefore, that the inventive concepts herein described are interchangeable and/or they can be used together in still other permutations of the present invention, and that other modifications and substitutions will be apparent to those skilled in the art from the foregoing description of the preferred embodiments without departing from the spirit or scope of the present invention.