Patent Publication Number: US-10330432-B2

Title: Adjustable firearm stock

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/416,884, filed Nov. 3, 2016, which is hereby specifically incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     Field of Use 
     This disclosure relates to firearms. More specifically, this disclosure relates to an adjustable firearm stock. 
     Related Art 
     A firearm such as, for example and without limitation, a semi-automatic rifle can comprise a firearm stock. When placed against the shoulder or other portion of a user&#39;s body, a firearm stock can help support and stabilize a first end of the firearm and help absorb any recoil force resulting from a discharge of the firearm during use. The stock of the firearm is typically built into the firearm. While sometimes the stock is adjustable based on the size of a user&#39;s body or other factors, the stock is not typically detachable or mountable to an accessory rail of the firearm, much less a standard accessory rail mounted on a side or a top of the firearm. A firearm that cannot be held comfortably and securely by every user can cause fatigue to some users and be less safe or less accurate during use. 
     SUMMARY 
     It is to be understood that this summary is not an extensive overview of the disclosure. This summary is exemplary and not restrictive, and it is intended to neither identify key or critical elements of the disclosure nor delineate the scope thereof. The sole purpose of this summary is to explain and exemplify certain concepts of the disclosure as an introduction to the following complete and extensive detailed description. 
     In one aspect, disclosed is an adjustable firearm stock comprising: a base configured to mount on a firearm comprising: an upper base body defining a first side surface defining an upper jaw, a second side surface distal from the first side surface, a first end surface, a second end surface distal from the first end surface, a top surface, a bottom surface distal from the top surface, an extension element bore extending from the first end surface to the second end surface, and a locking actuator bore extending from a one of the second side surface, the top surface, and the bottom surface into the upper base body; and a locking actuator positioned in the locking actuator bore; an extension element positioned in the extension element bore of the upper base body, the extension element configured to move along an axis defined by the extension element bore by operation of the locking actuator; and an end accessory coupled to the extension element and configured to rest against a user. 
     In a further aspect, disclosed is a firearm comprising: a rail; and an adjustable firearm stock comprising: a base removably secured to the rail of the firearm and defining an extension element bore; an extension element positioned in the extension element bore, the extension element configured to move along an axis of the extension element bore; and an end accessory secured to the extension element. 
     In yet another aspect, disclosed is a method of using a firearm comprising: mounting a base of an adjustable firearm stock to a rail of the firearm; and sliding an extension element of the adjustable firearm stock through an extension element bore of the base to adjust the firearm stock to a desired stock orientation. 
     In yet another aspect, disclosed is an adjustable firearm stock comprising: a base configured to mount on a rail of a firearm, the base comprising: an upper base body defining a first side surface defining an upper jaw, a second side surface distal from the first side surface, a first end surface, a second end surface distal from the first end surface, a top surface, a bottom surface distal from the top surface, an extension element bore extending from the first end surface to the second end surface, and a locking actuator bore extending from a one of the second side surface, the top surface, and the bottom surface into the upper base body; and a locking actuator positioned in the locking actuator bore; and an extension element positioned in the extension element bore of the upper base body, the extension element configured to move along an axis defined by the extension element by operation of the locking actuator. 
     In yet another aspect, disclosed is a firearm comprising: a rail secured to the firearm; and an adjustable firearm stock secured to the rail, the adjustable firearm stock comprising: a base removably secured to the rail of the firearm and defining an extension element bore; an extension element defining a first end defining a contact surface and a second end distal from the first end, the second end of the extension element extending at least partly through the extension element bore, the second end of the extension element positioned closer to a front end of the firearm than the first end of the extension element, the extension element configured to move along an axis of the extension element bore; and an end accessory secured to the first end of the extension element, the end accessory defining a contact surface having a greater surface area than a surface area of the contact surface of the first end of the extension element. 
     In yet another aspect, disclosed is a method of using a firearm comprising: mounting a base of an adjustable firearm stock to a rail of the firearm; sliding an extension element of the adjustable firearm stock through an extension element bore of the base to adjust the adjustable firearm stock to a desired orientation; and fixing a position of the extension element relative to the base by engaging a locking actuator of the adjustable firearm stock with the extension element. 
     Various implementations described in the present disclosure may comprise additional systems, methods, features, and advantages, which may not necessarily be expressly disclosed herein but will be apparent to one of ordinary skill in the art upon examination of the following detailed description and accompanying drawings. It is intended that all such systems, methods, features, and advantages be included within the present disclosure and protected by the accompanying claims. The features and advantages of such implementations may be realized and obtained by means of the systems, methods, features particularly pointed out in the appended claims. These and other features will become more fully apparent from the following description and appended claims, or may be learned by the practice of such exemplary implementations as set forth hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several aspects of the disclosure and together with the description, serve to explain various principles of the disclosure. The drawings are not necessarily drawn to scale. Corresponding features and components throughout the figures may be designated by matching reference characters for the sake of consistency and clarity. 
         FIG. 1  is perspective view of a firearm comprising an adjustable firearm stock in accordance with one aspect of the current disclosure. 
         FIG. 2  is an exploded perspective view of the adjustable firearm stock of  FIG. 1 . 
         FIG. 3  is a side view of the adjustable firearm stock of  FIG. 1 . 
         FIG. 4  is a sectional view of the adjustable firearm stock of  FIG. 1  taken from line  4 - 4  of  FIG. 3 . 
         FIG. 5  is a sectional view of the adjustable firearm stock of  FIG. 1  taken from line  5 - 5  of  FIG. 3 . 
         FIG. 6  is a bottom inside sectional perspective view of a base of the adjustable firearm stock of  FIG. 1 . 
         FIG. 7  is a sectional perspective view of the base of  FIG. 6 . 
         FIG. 8A  is a perspective view of a lower base body of the base of  FIG. 6 . 
         FIG. 8B  is a side view of the lower base body of  FIG. 6 . 
         FIG. 9  is a first side view of an extension element of the adjustable firearm stock of  FIG. 1 . 
         FIG. 10  is a top view of the extension element of  FIG. 9 . 
         FIG. 11  is a second side view of the extension element of  FIG. 9 . 
         FIG. 12  is a top inside perspective view of a locking actuator of the adjustable firearm stock of  FIG. 1 . 
         FIG. 13  is a bottom inside perspective view of the locking actuator of  FIG. 12 . 
         FIG. 14  is a side perspective view of an assembly comprising the adjustable firearm stock of  FIG. 1  in accordance with another aspect of the current disclosure. 
         FIG. 15  is a detail view of an accessory bracket of the assembly of  FIG. 14 . 
         FIG. 16  is a perspective view of the adjustable firearm stock in accordance with another aspect of the current disclosure. 
         FIG. 17  is a sectional view of the adjustable firearm stock of  FIG. 16  taken from line  17 - 17  of  FIG. 16 . 
         FIG. 18  is a sectional view of the adjustable firearm stock of  FIG. 16  taken from line  18 - 18  of  FIG. 16 . 
         FIG. 19  is a top front perspective view of a locking actuator of the adjustable firearm stock of  FIG. 16 . 
         FIG. 20  is a top rear perspective view of the locking actuator of  FIG. 19 . 
         FIG. 21  is a bottom front perspective view of the locking actuator of  FIG. 19 . 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure can be understood more readily by reference to the following detailed description, examples, drawings, and claims, and their previous and following description. However, before the present devices, systems, and/or methods are disclosed and described, it is to be understood that this disclosure is not limited to the specific devices, systems, and/or methods disclosed unless otherwise specified, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. 
     The following description is provided as an enabling teaching of the present devices, systems, and/or methods in their best, currently known aspect. To this end, those skilled in the relevant art will recognize and appreciate that many changes can be made to the various aspects described herein, while still obtaining the beneficial results of the present disclosure. It will also be apparent that some of the desired benefits of the present disclosure can be obtained by selecting some of the features of the present disclosure without utilizing other features. Accordingly, those who work in the art will recognize that many modifications and adaptations to the present disclosure are possible and can even be desirable in certain circumstances and are a part of the present disclosure. Thus, the following description is provided as illustrative of the principles of the present disclosure and not in limitation thereof. 
     As used throughout, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a quantity of one of a particular element can comprise two or more such elements unless the context indicates otherwise. 
     Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another aspect comprises from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. 
     For purposes of the current disclosure, a material property or dimension measuring about X or substantially X on a particular measurement scale measures within a range between X plus an industry-standard upper tolerance for the specified measurement and X minus an industry-standard lower tolerance for the specified measurement. Because tolerances can vary between different materials, processes and between different models, the tolerance for a particular measurement of a particular component can fall within a range of tolerances. 
     As used herein, the terms “optional” or “optionally” mean that the subsequently described event or circumstance may or may not occur, and that the description comprises instances where said event or circumstance occurs and instances where it does not. 
     The word “or” as used herein means any one member of a particular list and also comprises any combination of members of that list. 
     To simplify the description of various elements disclosed herein, the conventions of “left,” “right,” “front,” “rear,” “upper,” “lower,” “up,” “down,” “top,” “bottom,” “inside,” “outside,” “inboard,” “outboard,” “horizontal,” and/or “vertical” may be referenced. Unless stated otherwise, “rear” describes that end of the firearm or the adjustable firearm stock nearest to the user when the firearm and/or the adjustable firearm stock is used as intended; “front” is that end of the firearm or the adjustable firearm stock that is opposite or distal from the rear; “left” is that which is to the left of or facing left from the user&#39;s perspective; and “right” is that which is to the right of or facing right from the user&#39;s perspective. “Upper,” “up,” and “top” refers to that which is proximate to or facing an upper portion of the firearm or the adjustable firearm stock, while “lower,” “down,” “and “bottom” refer to that which is opposite or distal from that which is “upper,” “up,” or “top.” “Vertical” or “vertical orientation” describes that which is in a plane extending upwards when the firearm is in an upright position with a bore axis of the firearm in a level position. “Horizontal” or “horizontal orientation” describes that which is in a plane that extends from left to right and normal to the vertical plane when the firearm is in an upright position with a bore axis of the firearm in a level position. When describing features or areas of the firearm or the adjustable firearm stock, it is to be understood that the firearm or the adjustable firearm stock is itself upright and level. 
     In one aspect, an adjustable firearm stock and associated methods, systems, devices, and various apparatuses are disclosed herein. In one aspect, the adjustable firearm stock can comprise a base and an extension element. In another aspect, the adjustable firearm stock can further comprise an end accessory. 
       FIG. 1  shows a firearm  100 , which can comprise an adjustable firearm stock  200 . The firearm  100  can comprise a receiver  110 , a barrel  120 , a grip  130 , a trigger (not shown), a trigger guard  140 , an ammunition magazine  150 , a dust cover  160 , a rail mount plate  170  (shown in  FIG. 2 ), a front sight  180   a , and a rear sight  180   b . The receiver  110  can effectively provide a central structure to which various components including the barrel  120 , the grip  130 , the trigger (not shown), the trigger guard  140 , the ammunition magazine  150 , the dust cover  160 , and the rail mount plate  170  can be attached. The barrel  120 , at least a portion of which can be covered with a lower handguard  122  and an upper handguard  124 , can define a bore axis  121  of the firearm  100  with which a bullet fired from the firearm  100  is coaxial and along which the bullet is expelled from the firearm  100 . 
     A cavity  112  at the rear of the receiver  110 , which can ordinarily be configured to receive a fixed stock (not shown) and a rear trunnion  185  to secure the fixed stock, can also be configured to receive a rear cover  190 , which can be a plug. In one aspect, the rear cover  190  can be a molded part that is inserted into the cavity  112  and optionally around the rear trunnion  185 . In another aspect, the rear cover  190  can be stamped or fabricated using any other method of manufacture. In yet another aspect, the rear cover  190  can be configured to hinge open and closed. In yet another aspect, the rear cover  190  can be secured to the receiver  110  with fasteners (not shown). In one aspect, the rear cover  190  can be used to cover and protect the rear of the firearm  100  including the rear trunnion  185  from damage such as, for example and without limitation, impact forces or soiling. In another aspect, the rear cover  190  can protect a user from possibly injury by the rear trunnion  185  or otherwise partially assembled rear portion of the firearm  100 . In yet another aspect, the rear cover  190  can be configured to receive a quick-disconnect lanyard, sling, or harness or other accessory. In yet another aspect, the rear cover  190  can be used for storage by defining a cavity for inserting an item to be stored. 
     The firearm  100  can be a rifle; however, in some other aspects, the firearm  100  can be a shotgun or other long gun. In one aspect, the firearm  100  can be an “automatic” firearm in which a single depression of the trigger can fire multiple shots. In another aspect, the firearm  100  can be a “semi-automatic” firearm in which a single depression of the trigger fires only a single shot. In aspects in which the firearm  100  is an automatic firearm or a semi-automatic firearm, an action of the firearm  100  automatically cycles and reloads the chamber (not shown) with ammunition (not shown) from the ammunition magazine  150  after each shot. In yet another aspect, the firearm  100  can be a “manual” firearm in which a single depression of the trigger typically fires only one single shot and does not reload the chamber with ammunition. Manual firearms can comprise various action types such as a bolt action, lever action, or pump action wherein the action can be manually cycled by manipulation of a bolt, a lever, or a pump grip, respectively. For example and without limitation, the firearm  100  can be a type of firearm identified as an AK-47 firearm. Commercial and military variants of the AK-47 firearm and related designs can include, for example and without limitation, models such as an RPK firearm, an AKM firearm, an AK-74 firearm, an AK-101 firearm, an AK-103 firearm, an AK-104 firearm, a SAIGA firearm, a Dragunov firearm, a PSL firearm, an AKSU firearm, or other variants manufactured by any one of a number of manufacturers and countries. However, any firearm can be configured to receive the adjustable firearm stock  200 , including by addition of the rail mount plate  170  if such is not already installed. 
     The adjustable firearm stock  200  can comprise a base  210 , an extension element  300 , an end accessory  400 , and a stop collar  500 . The base  210  can be receivable on the firearm  100 . The extension element  300  can be receivable within the base  210 . The end accessory  400  and the stop collar  500  can be receivable on the extension element  300 . 
     Since permanent modification of the firearm to accommodate an adjustable firearm stock is not always desirable for safety or performance reasons, using a standard accessary rail can be a convenient way to create new functionality. As shown in the exploded view of  FIG. 2 , the adjustable firearm stock  200  can be mounted to the receiver  110  of the firearm  100  via a rail mount plate  170  that can be configured to be received within a receiving portion  215  (shown in  FIG. 4 ) of the base  210 . The rail mount plate  170  can also be referred to as a “side rail scope mount” or a “rail side mount” or simply a “scope mount” or a “rail mount.” The rail mount plate  170  is typically used only to mount an optics, which can include, e.g., a scope, a red dot sight, and a holosight, which the user can use to aim the firearm  100 . In one aspect, as shown in  FIG. 2 , the rail mount plate  170  can be mounted to a first side  116  of the receiver  110  ora second side  118  of the receiver  110 , which can be opposite from the first side  116  on the firearm  100 . The first side  116  and the second side  118  can define a first side vertical surface  117  and a second side vertical surface  119  (shown in  FIG. 4 ), respectively. In another aspect, the adjustable firearm stock  200  can be mounted to any other surface of the firearm  100  as desired, using the rail mount plate  170  or a portion of the firearm  100  that incorporates the geometry of an accessory rail such as the rail mount plate  170 . In another aspect, the adjustable firearm stock  200  can attach to an accessory rail formed by a portion of the receiver  110  or the dust cover  160 , such as an accessory rail integrally machined into a portion of the receiver  110  or the dust cover  160 . 
     On some firearms, the dust cover  160  can be replaced by an upper receiver. As shown, the rail mount plate  170  itself can be mounted to the firearm  100  using fasteners  179 , which, for example and without limitation, can be screws or rivets sized to be received within counterbored holes  178   a,b,c  (shown in  FIG. 6 ) defined in an outer surface  171  of the rail mount plate  170 . As shown, the rail mount plate  170  can be mounted to the firearm  100  using a pair of fasteners  179  installed through the counterbored holes  178   a,b,c . The rail mount plate  170  can comprise a dovetail portion  172  and a mounting portion  174 . The dovetail portion  172  can extend from a first end  175  to a second end  176  or along any portion thereof. 
     In one aspect, the rail mount plate  170  can be a side dovetail rail mount plate, which can comprise a portion having a dovetail shape as shown in the sectional view of  FIG. 4 . A dovetail shape is that which in cross-section flares out like the tail of a dove in flight in such a way that the “base” of the “tail” is narrower than the “tip” of the “tail.” More specifically, as shown in  FIG. 2 , the rail mount plate  170  can be an AK-type rail mount plate that is typically used on an AK-47 firearm and similar firearms. In another aspect, the rail mount plate  170  can have another cross-sectional shape, and the receiving portion  215  of the base  210  can be shaped to match. While the AK-type rail mount shown in  FIG. 2  is a commonly available type, variations in size and shape can be found on some firearms. For example and without limitation, the adjustable firearm stock  200  can be configured to attach to a Picatinny or MIL-STD-1913 rail, which can also be referred to as a “tactical rail”; a Weaver rail; or any rail mount comprising a dovetail shape in cross-section, any of which could be considered an accessory rail  1600  (shown in  FIG. 16 ). 
     Also shown in  FIGS. 2 and 3 , the base  210  can comprise an upper base body  220 , a lower base body  240 , a locking actuator  250 , an activator-biasing mechanism  260  (shown in  FIG. 2 ), pins  280  (shown in  FIG. 2 ), and body assembly fasteners  290 . The upper base body  220  can define a first side surface  221  (shown in  FIG. 4 ) defining an upper jaw  223  (shown in  FIG. 4 ) and a second side surface  222  distal from the first side surface  221 . The upper base body  220  can define a first end surface  225  and a second end surface  226  (shown in  FIG. 3 ) distal from the first end surface  225 . The upper base body  220  can define a top surface  228  and a bottom surface  229  (shown in  FIG. 3 ) distal from the top surface  228 . The upper base body  220  can define an extension element bore  231  (shown in  FIG. 2 ) sized to receive the extension element  300  and extending from the first end surface  225  to the second end surface  226 . The extension element  300  can be positioned in or inside the extension element bore  231 , which can encompass structures and methods in which only a portion of the extension element  300  is positioned inside the extension element bore  231  and a portion of the extension element  300  extends outside of the extension element bore  231 . In one aspect, as shown, the extension element bore  231  can be fully enclosed within the base  210  (i.e., visible only at the first end surface  225 , at the second end surface  226 , or through a locking actuator bore  233 ). In another aspect, the extension element bore  231  can intersect and be visible at the top surface  228 , the bottom surface  229 , the first side surface  221 , or the second side surface  222  (i.e., the extension element bore  231  can be a groove defined in a surface of the base  210  and configured to receive and retain the extension element  300 ). In one aspect, as shown, the upper base body  220  can further define the locking actuator bore  233  (shown in  FIG. 2 ) extending from the top surface  228 . In another aspect, the locking actuator bore  233  can extend from any other surface of the upper base body  220  such as, for example and without limitation, the second side surface  222  or the bottom surface  229 . 
     The activator-biasing mechanism  260  can comprise at least one spring. In one aspect, the activator-biasing mechanism  260  can comprise a spring  265  such as, for example and without limitation, a coil spring, a wave spring, a leaf spring, or any other kind of spring that can store a potential force upon deformation during movement to an unlocked position and then return a part such as the locking actuator  250  to its original position, which can be a locked position in which the extension element  300  is fixed in position relative to the base  210 . As shown, the activator-biasing mechanism  260  can comprise two springs  265  configured to provide equal return force in an upward direction to each of two ends of the locking actuator  250 . 
     The extension element  300 , which can be a rod or a shaft in one aspect, can comprise a first end  305  and a second end  306  distal from the first end  305  and can define an axis  301 . The second end  306  of the extension element  300  can be positioned closer to a front end of the firearm  100  than the first end  305  of the extension element  300 . The extension element  300  can further define an engagement feature  330 , which can comprise indentations  332  that are configured to engage the locking actuator  250 , as will be described. The extension element  300  can further comprise a first side  310  and a second side  320 . The first side  310  and the second side  320  (shown in  FIGS. 4 and 5 ) can comprise a first side surface  311  and a second side surface  321  (shown in  FIGS. 4 and 5 ). In one aspect, each of the first side surface  311  and the second side surface  321  can be a flattened or planar side surface of the otherwise round extension element  300  configured to prevent rotation of the extension element  300  about the axis  301 . More specifically, the first side surface  311  and the second side surface  321  can be configured to contact the pins  280  and thereby prevent rotation. In one aspect, the extension element  300  can be substantially cylindrical, i.e., substantially circular in cross-section, when viewed along the axis  301 . In another aspect, the extension element  300  can have another shape in cross-section such as, for example and without limitation, a rectangular or polygonal shape. Whatever the shape of the extension element  300  or the first side surface  311  or the second side surface  321  thereof, the extension element  300  can comprise at least one anti-rotation feature that together with the base  210  prevents rotation of the extension element  300  inside the base  210 . The extension element  300  can define at least one hole  382  proximate to the first end  305  and at least one hole  382  proximate to the second end  306  for attachment of the end accessory  400  and the stop collar  500 , respectively. In another aspect, an adjustable firearm stock can comprise a pair of extension elements, one adjacent to the other and each received within one of a pair of extension element bores defined in the body of the adjustable firearm stock. 
     In one aspect, the extension element  300  can define at least one hole  386  between the first end  305  and the second end  306  for attachment of a second stop collar  500  (not shown). In another aspect, the end accessory  400  can be removed and a cheek pad (not shown) or other accessory can be secured proximate to the first end  305  of the extension element  300 . In yet another aspect, any number and combination of holes  382 , 386  proximate to the first end  305  of the extension element  300  can be used to secure an end accessory  400  or a pad  450  (shown in  FIG. 5 ), which can include features of the cheek pad. The cheek pad can be a cushioned pad and can be raised from or offset from the extension element  300 . The cheek pad can define a padded surface substantially parallel to the bore axis  121 . The cheek pad can be configured to align an eye of the user with the sights  180   a,b  or an optic (not shown) when a cheek of the user rests upon the cheek pad. As shown, the extension element  300  defines one pair each of the holes  382 , 384 , 386 . 
     The first end  305  of the extension element  300  can define a contact surface  1690 , and a second portion  420  of the end accessory  400  can define a contact surface  421 . The contact surface  421  can have a greater surface area than a surface area of the contact surface  1690  of the first end  305  of the extension element  300 . By having a greater surface area, the contact surface  421  can distribute the force acting on the user, for example, over a greater area and therefore reduce the pressure felt at any single point. 
     In one aspect, the end accessory  400  can comprise a first portion  410 , which can comprise a boss, sized to receive the extension element  300 , and the second portion  420 , which can comprise a plate. In one aspect, the end accessory  400  can be sized and configured to fit against a portion of the user&#39;s body. In another aspect, the end accessory  400  can be sized and configured to receive the pad  450  (shown in  FIG. 5 ), which can be sized to fit against a portion of the user&#39;s body and optionally provide a cushion between the end accessory  400  and the user. The first portion  410  of the end accessory  400  can define a central bore  412  (shown in  FIG. 5 ) for receiving the extension element  300  and at least one side bore  414  for receiving a pin  480  that can secure the end accessory  400  to the extension element  300 . As shown, the first portion  410  can define a pair of side bores  414 , and the end accessory  400  can be secured to the extension element  300  with a pair of pins  480 . In another aspect, the end accessory  400  can be secured to the extension element  300  without fasteners. The end accessory  400  can be, for example and without limitation, a butt plate, a butt stock, a stabilizer, a strap, a fin, a flap, a bumper, a plug, a cap, a brace such as an arm brace, or a rounded shape such as a ball, any of which can be secured to the first end  305  of the extension element  300 . 
     The stop collar  500  can comprise a body  510  sized to receive the extension element  300 . The body  510  can define a central bore  512  (shown in  FIG. 5 ) for receiving the extension element  300  and at least one side bore  514  for receiving a pin  580  that can secure the stop collar  500  to the extension element  300 . As shown, the body  510  can define a pair of side bores  514 , and the stop collar  500  can be secured to the extension element  300  with a pair of pins  580 . In one aspect, each of the pins  280 , 480 , 580  can be a roll pin, which can be referred to as a spring pin. In another aspect, each of the pins  280 , 480 , 580  can be any other kind of fastener receivable within the respective bore. 
     In one aspect, as shown, either of the first end  305  and the second end  306  of the extension element  300  can comprise a plain end. In another aspect, either of the first end  305  and the second end  306  of the extension element  300  can comprise a threaded portion. In one aspect, as shown, either of the central bore  412  of the end accessory  400  and the central bore  512  of the stop collar can be smooth. In another aspect, either of the central bore  412  of the end accessory  400  and the central bore  512  of the stop collar can be threaded, for example and without limitation, to threadably engage the extension element  300 . In one aspect, as shown, any of the pins  280 , 480 , 580  can have a plain end. In another aspect, any of the pins  280 , 480 , 580  can comprise a threaded portion. In one aspect, as shown, any of the bores  288 , the holes  382 , 384 , 386 , and the side bores  414 , 514  can be smooth. In another aspect, any of the bores  288 , the holes  382 , 384 , 386 , and the side bores  414 , 514  can be threaded. 
     As shown in  FIG. 3 , a bottom end  114  and a bottom surface  115  of the bottom end  114  of the receiver  110  can, for example and without limitation, be angled with respect to the horizontal direction and can be angled with respect to the axis  301  of the extension element  300 . The receiver  110  is not limited to any particular size or shape as long as it can receive the adjustable firearm stock  200 . The base  210  and the end accessory  400  can define an adjustment distance  308  measured from the first end surface  225  of the base  210  to the first portion  410  of the end accessory  400 , the adjustment of which can render the adjustable firearm stock  200  collapsible. The adjustable firearm stock  200  can define an overall extension distance  309  (shown in  FIG. 5 ) from a centerline  177  (shown in  FIG. 5 ) of the rail mount plate  170  to the second portion  420  of the end accessory  400 . 
     As shown in  FIG. 4 , the upper jaw  223  of the upper base body  220  and a lower jaw  243  of the lower base body  240  can clamp about the dovetail portion  172  of the rail mount plate  170  to effectively secure the base  210  to the firearm  100 . A distance  217  between the upper jaw  223  and the lower jaw  243  can be made adjustable by adjusting the body assembly fasteners  290 . Each of the body assembly fasteners  290  can comprise a head  292  and a shank  294  having a first end  295  proximate the head  292  and a second end  296  distal from the first end  295 . 
     In one aspect, as shown in  FIG. 4 , the axis  301  of the extension element  300  can be offset vertically with respect to (i.e., positioned above or below) the bore axis  121  of the barrel  120  of the firearm  100  by an offset distance  302 . In another aspect, the axis  301  of the extension element  300  can be aligned vertically with the bore axis  121  of the barrel  120  of the firearm  100 . In one aspect, as shown in  FIG. 5 , the axis  301  of the extension element  300  can be offset horizontally with respect to the bore axis  121  of the barrel  120  of the firearm  100  by an offset distance  303 . In another aspect, the axis  301  of the extension element  300  or a portion of the extension element  300  can be aligned with the bore axis  121  of the barrel  120  of the firearm  100 . In one aspect, for example and without limitation, at least a portion of the extension element  300  can be positioned directly to the rear of the barrel  120  so that it is inline with the bore axis  121 , by introducing a bend in the extension element  300  so that an axis of the extension element  300  at the first end  305  is aligned with the bore axis  121 . In another aspect, for example and without limitation, a bracket (not shown) can be attached to the extension element  300  so that a portion of the bracket intersects with the bore axis  121 . In yet another aspect, as shown in  FIG. 5 , at least a portion of the end accessory  400  or the pad  450  can be sized and positioned to extend sufficiently in a horizontal direction to overlap the bore axis  121  by an overlap distance  460  such that a portion of the adjustable firearm stock  200  pushes back against the kickback of the firearm  100  during firing of the firearm  100  along the bore axis  121 . 
     As shown in  FIGS. 4 and 5 , the upper base body  220  can comprise assembly bores  298   a,b  (shown in  FIG. 5 ), which can be sized to receive the body assembly fasteners  290  and can extend from the top surface  228  to the bottom surface  229 . Each of the assembly bores  298   a,b  can be defined as smooth-bore holes in the upper base body  220 . The upper base body  220  can comprise pin bores  288   a,b,c,d  sized to receive the pins  280  and also extending from the top surface  228  to the bottom surface  229 . As shown in  FIG. 4 , the pins  280  installed in the pin bores  288   a,b , respectively, can contact the first side surface  311  of the first side  310  of the extension element  300 , and the pins  280  installed in the pin bores  288   a,b , respectively, can contact the second side surface  321  of the second side  320  of the extension element  300 . Thus the pins  280  together can maintain the tight lateral position of the extension element  300  (i.e., the pins  280  can prevent misalignment of the axis  301  of the extension element  300  with an axis of the extension element bore  231 ) and prevent rotation of the extension element  300  about the axis  301  while inside the extension element bore  231 . 
     As shown in  FIGS. 4 and 5 , the engagement feature  330 , which can comprise the indentations  332 , can be configured to engage teeth  252  of the locking actuator  250 . When the locking actuator  250  is in a raised position (i.e., a non-depressed position, which can also be a locked position) as shown in  FIG. 4 , the teeth  252  of the locking actuator  250  can be made to interlock with the indentations  332  of the engagement feature  330  of the extension element  300 . When the teeth  252  interlock with the indentations  332 , the extension element  300  can be held stationary inside the extension element bore  231  of the base  201  and cannot move in a direction along the axis  301 , i.e., the extension element  300  is locked in place relative to the base  210 . In one aspect, as shown in  FIG. 4 , the teeth  252  can have a triangular shape in cross-section when viewed along the axis  301 . In another aspect, as shown in  FIG. 5 , the teeth  252  can also have a triangular shape in cross-section when viewed from a direction facing downward and can be made to substantially match the triangular shape in cross section of the indentations  332  of the extension element  300  when viewed from the same direction. In yet another aspect, the teeth  252  can comprise any sloped or angled surface. 
     As shown in  FIG. 6 , the upper base body  220  can further comprise a stop portion  224 . The stop portion  224  can be defined in the first side surface  221  proximate to the first end surface  225  and can comprise a shoulder  234 . The shoulder  234  can face a direction opposite the first end surface  225  (shown in  FIG. 3 ) and towards the first end  175  of the rail mount plate  170  when the rail mount plate  170  is captured within the receiving portion  215  (shown in  FIG. 4 ) of the base  210  (shown in  FIG. 4 ). The stop portion  224  can be useful in preventing the firearm  100  from moving towards the user—for example, during the firing of ammunition from the firearm  100 . For example, even when the adjustable firearm stock  200  is not tightened completely around the rail mount plate  170  such that the frictional forces between the adjustable firearm stock  200  and the rail mount plate  170  are insufficient to prevent movement of the adjustable firearm stock  200  with respect to the rail mount plate  170 , the presence of the stop portion  224  can prevent such movement. Nonetheless, it can generally be beneficial to completely tighten the adjustable firearm stock  200  around the rail mount plate  170 , as the design uniquely allows, to prevent unintended movement of the adjustable firearm stock  200  with respect to the rail mount plate  170  and therefore also prevent unintended movement of the firearm  100  with respect to the adjustable firearm stock  200 . 
     The upper base body  220  can further comprise an extension portion  227 , which can be made to extend past the second end surface  226 . Likewise, the lower base body  240  can be made to extend past the second end surface  226 . Extending the extension portion  227  of the upper base body  220  and the lower base body  240  can increase a length of the receiving portion  215  (shown in  FIG. 4 ) to match a length of the dovetail portion  172  of the rail mount plate  170 , which can have the benefit of improving the rigidity of the connection between the adjustable firearm stock  200  and the firearm  100  and preventing the rotation of the adjustable firearm stock  200  with respect to the firearm  100 . 
     Also shown in  FIG. 6 , the lower base body  240  can comprise assembly bores  248   a,b  sized to receive the body assembly fasteners  290  and can extend from a top surface  247  (shown in  FIG. 8A ) to a bottom surface  249  of the lower base body  240 . Each of the assembly bores  248   a,b  can be defined as tapped holes in the lower base body  240 . The assembly bores  248   a,b  can be tapped to receive and engage the body assembly fasteners  290  and specifically the threaded second end  296  of each. 
     As shown in  FIG. 7 , the locking actuator bore  233  can extend from the top surface  228  of the upper base body  220  to a depth between a lowermost portion of the extension element bore  231  and the bottom surface  229  of the upper base body  220 . The depth of the locking actuator bore  233  can provide space for the activator-biasing mechanism  260  or any portion thereof—such as the springs  265 —in both its compressed and uncompressed states. 
     As shown in  FIGS. 8A and 8B , the lower base body  240  can be bowed or pre-bent before its assembly to the upper base body  220 . As shown in  FIG. 8B , the bottom surface  249  of the lower base body  240  can define a radius R representing a radius of curvature of the bottom surface  249 . Tightening of the body assembly fasteners  290  can bring the lower base body  240  closer to the upper base body  220 . When the lower base body  240  is bowed or pre-bent as shown, however slight the bow or bend, tightening the body assembly fasteners  290  can result in the creation of a contact pressure against the upper base body  220  by the lower base body  240  that can thereby increase the friction between the upper base body  220  and the lower base body  240 . Increased friction between the upper base body  220  and the lower base body  240  can increase the security and reliability of the connection between the adjustable firearm stock  200  and the rail mount plate  170  of the firearm  100 . In another aspect, the lower base body  240  can be bowed or bent in an opposite direction to that shown. In one aspect, the lower base body  240  can be made from spring steel, which is intended to repeatedly elastically deform. 
     As shown in  FIGS. 9-11 , the extension element  300  can comprise the first side  310 , the second side  320 , the first end  305 , the second end  306 , the engagement feature  330 , the indentations  332 , and the holes  382 , 384 , 386 . Each of the indentations  332  can comprise a sloping portion  333  and a stop portion  334 . Both a surface of the sloping portion  333  and a surface of the stop portion  334  can be angled with respect to the first side surface  311  of the first side  310 . In one aspect, a surface of the sloping portion  333  can be angled at an angle of 20 degrees with respect to the first side surface  311 . In another aspect, a surface of the sloping portion  333  can be angled at an angle of between zero and 90 degrees with respect to the first side surface  311 . In one aspect, a surface of the stop portion  334  can be angled at an angle of 90 degrees with respect to the first side surface  311 . In another aspect, a surface of the stop portion  334  can be angled at an angle measuring less than or greater than 90 degrees with respect to the first side surface  311 . 
     As shown in  FIGS. 12 and 13 , the locking actuator  250  can comprise a first portion  255 , which can be a top end, and a second portion  257 , which can be a bottom end, distal from the first portion  255 . A connecting portion  251 , which can be considered an upright or column of the locking actuator  250 , can extend from the first portion  255  to the second portion  257 . The first portion  255  can define a surface  256 . In one aspect, as shown the surface  256  can be textured, which can, for example and without limitation, help a user easily locate and position a finger on the locking actuator  250  or help the user maintain the position of the finger on the locking actuator  250  while adjusting a position of the extension element  300  with respect to the base  210 . Each of the teeth  252  of the locking actuator  250  can comprise a sloping portion  253  and a stop portion  254 . Both a surface of the sloping portion  253  and a surface of the stop portion  254  can be angled with respect to a surface of an inside wall  258  of the locking actuator  250 . In one aspect, a surface of the sloping portion  253  can be angled at an angle of  20  degrees with respect to the surface of the inside wall  258 . In another aspect, a surface of the sloping portion  253  can be angled at an angle of between zero and 90 degrees with respect to the surface of the inside wall  258 . In one aspect, a surface of the stop portion  254  can be angled at an angle of 90 degrees with respect to the surface of the inside wall  258 . In another aspect, a surface of the stop portion  254  can be angled at an angle measuring less than or greater than 90 degrees with respect to the surface of the inside wall  258 . The stop portion  254  of the locking actuator  250  can be oriented normal to the axis  301  and positioned at a rear end of each tooth  252  to better resist the recoil impulse of the firearm  100  during its firing. More specifically, the adjustable firearm stock  200  can be so designed to resist the compressive force that results between the stop portion  254  of the locking actuator  250  and the stop portion  334  of the extension element  300  during the firing of the firearm  100 . 
     In one aspect, as shown in  FIG. 12 , the tooth can have a lower profile that occupies less space in the area between the first portion  255  and the second portion  257 . In one aspect, as shown in  FIG. 4 , each of the teeth  252  can have a higher or taller profile that occupies more space in the area between the first portion  255  and the second portion  257 . As shown in  FIG. 13 , the second portion  257  can define at least one cavity  259   a,b , which can receive a portion of the activator-biasing mechanism  260 . In one aspect, the second portion  257  of the locking actuator  250  can comprise a pair of the cavities  259   a,b , one cavity  259   a,b  each for each of the pair of springs  265  of the activator-biasing mechanism  260 . In another aspect, a single unbroken cavity can be defined in and extend across a bottom surface of the locking actuator  250  to accommodate the activator-biasing mechanism  260 . 
     As shown in  FIG. 14 , the adjustable firearm stock  200  can comprise the pad  450  attached to the end accessory  400 . In one aspect, as shown, the second portion  420  of the end accessory  400  can extend downwards from the first portion  410 . In another aspect, as shown in  FIG. 2 , the second portion  420  of the end accessory  400  can extend to the left or the right from the first portion  410 . In one aspect, the pad  450  can extend in a substantially vertical direction. The pad  450  can be secured to the end accessory  400  with fasteners  458 . 
     The adjustable firearm stock  200  can also comprise an accessory mount  600  that can mount to a top surface  228  of the base  210 . The accessory mount  600  can comprise a first mounting portion  610  configured to contact the top surface  228  of the base  210 . The accessory mount  600  can comprise a second mounting portion  620 , which can in one aspect be configured to receive an accessory such as a scope (not shown). In another aspect, the second mounting portion  620  can be configured to receive the accessory rail  1600  (shown in  FIG. 16 ) such as, for example and without limitation, the aforementioned Picatinny, MIL-STD-1913, or Weaver rails. In yet another aspect, the second mounting portion  620  can comprise a rail comprising an RSM mount. A riser  630  can extend between and connect the first mounting portion  610  and the second mounting portion  620 . In one aspect, the riser  630  can bend up and over the firearm  100  such that the accessory mounted to the accessory mount is directly above the bore axis  121  (shown in  FIG. 1 ). 
     As shown in  FIG. 15 , the first mounting portion  610  of the accessory mount  600  can define mounting bores  613   a,b  positioned proximate first and second ends of the first mounting portion  610 . Each of the mounting bores  613   a,b  can be sized to receive the body assembly fastener  290  and can be counterbored to receive the head  292  of each body assembly fastener  290 . The second mounting portion  620  of the accessory mount  600  can define mounting bores  623   a,b  positioned proximate first and second ends of the second mounting portion  620 . The mounting bores  623   a,b  can be sized to receive fasteners (not shown) for mounting an accessory (not shown) or a rail such as the accessory rail  1600  (shown in  FIG. 16 ) to which the accessory can be secured. Each of the mounting bores  623   a,b  can be tapped to receive the threaded shank of a rail mounting fastener (not shown) or an accessory mounting fastener (not shown). The second mounting portion  620  can further comprise a mounting surface  621 . The riser  630  can comprise a first riser portion  630   a  and a second riser portion  630   b.    
     As shown in  FIG. 16 , the locking actuator  250  of the adjustable firearm stock  200  can be positioned proximate to the first end surface  225  (shown in  FIG. 17 ) as shown or the second end surface  226 . The locking actuator  250  can be centered about the axis  301  of the extension element  300 . Moreover, a lengthwise direction of the locking actuator bore  233  can be oriented at 90 degrees with respect to the axis  301  and to the orientation shown in  FIG. 1 . In other aspects, the lengthwise direction of the locking actuator bore  233  (shown in  FIG. 17 ) and the locking actuator  250  itself can be oriented at a different angle than that shown in  FIG. 1  or in  FIG. 16 . In some aspects, the extension element  300  can extend through an opening  1910  (shown in  FIG. 19 ) defined in the locking actuator  250 . As shown, the extension element  300  can comprise a first portion extending along the axis  301  and a second portion  370  extending along a secondary axis  304 , which can be angled with respect to the axis  301 . 
     In one aspect, as shown in  FIG. 17 , the engagement feature  330  and, more specifically, sloping surfaces of the indentations  332  of the engagement feature  330  can face away from the first portion  255  of the locking actuator  250  and away from the top surface  228  of the upper base body  220 , i.e., downward when the firearm  100  is positioned right-side up; and the engagement feature  330  and, more specifically, the sloping surfaces of the indentations  332  of the engagement feature  330  can face toward from the second portion  257  of the locking actuator  250  and toward the bottom surface  229  of the upper base body  220  and toward the direction of the centerline axis  1701  of the locking actuator  250 . The sloping portion  253  of the tooth  252  of the locking actuator  250  can face toward the sloping surface of any one of the indentations  332 . As described above, pushing down the locking actuator  250  relative to the upper base body  220  can disengage the tooth  252  from the engagement features  330  of the extension element  300 , which can allow movement of the extension element  300  relative to the upper base body  220 . In another aspect, the engagement feature  330  and, more specifically, the sloping surfaces of the indentations  332 , can be made to face the opposite direction. The locking actuator  250  modified accordingly. 
     As shown in  FIG. 18 , the second side surface  321  of the second side  320  of the extension element  300  can ride against the shank  294  of each of the body assembly fasteners  290 . Movement of the extension element  300  in a direction orthogonal to the axis  301  caused by looseness between the extension element  300  and the extension element bore  231  can be minimized or eliminated by the shank  294  of each of the body assembly fasteners  290 . The shank  294  of the body assembly fasteners  290  can thereby replace the function of and obviate the need for the aforementioned pins  280  (shown in  FIG. 4 ). Each of the body assembly fasteners  290  can comprise a head  292  defining a countersunk shape as shown. 
       FIGS. 19-21  show the locking actuator  250  in accordance with an aspect of the disclosure shown in  FIGS. 16-18 . In one aspect, as shown in  FIG. 19 , the connection portion  251  extending from the first portion  255  to the second portion  257  can be formed on both lateral sides of the tooth  252 , thereby forming the opening  1910  therethrough. In another aspect, the connection portion  251  can be formed on just one side of the tooth  252 . In another aspect, the locking actuator  250  can have a different shape from that show when viewed from the front, rear, side, top, or bottom. As shown, the inside wall  258  can define the opening  1910  of the locking actuator  250 . As shown in  FIG. 20 , the stop portion  254  can be defined in the tooth  252  on a side opposite from the sloping portion  253  (shown in  FIG. 19 ). As shown in  FIG. 21 , the locking actuator  250  can define the aforementioned bores  259   a,b  in the second portion  257 . 
     The adjustable firearm stock  200  can comprise additional features as desired. For example, the end accessory  400  or the pad  450  can further comprise a biasing mechanism (not shown) configured to allow rotation of the end accessory or the pad  450  about the axis  301  with respect to the extension element  300 . In addition, in another aspect of the adjustable firearm stock  200 , the body assembly fasteners  290  can comprise a quick-release tightening mechanism (not shown) configured to tighten the adjustable firearm stock  200  to the firearm  100  without a separate tool. In one aspect, for example and without limitation, the head  292  of each of the body assembly fasteners  290  can incorporate a cam mechanism that allows gross adjustment and/or fine adjustment of the distance  217  and then “locking” of the adjustable firearm stock  200  around the rail mount plate  170 . In another aspect, the lower jaw  243  can be replaced with one or more cams configured to engage the dovetail portion  172  of the rail mount plate  170  upon rotation of each of the one or more cams. Each cam can define either a variable perimeter thickness or a variable outer radius or both the variable perimeter thickness and the variable outer radius and can be configured to exert an increasing force on the dovetail portion  172  as the cams are rotated. 
     A method of using a firearm  100  can comprise securing a rail mount plate  170  to the side vertical surface  117 , 119  of the receiver  110  of the firearm  100 . The method can further comprise mounting the base  210  of the adjustable firearm stock  200  to the rail mount plate  170  of the firearm  100 . The method can further comprise sliding an extension element  300  of the adjustable firearm stock  200  along the axis  301  of the extension element bore  231  of the base  210  and within the extension element bore  231  of the base. The method of mounting the base  210  of the adjustable firearm stock  200  to the rail mount plate  170  can further comprise bringing the lower jaw  243  of the base  210  towards the upper jaw  223  of the base  210  to secure the base  210  to the rail mount plate  170 . The method can further comprise engaging a tooth  252  of the locking actuator  250  with an indentation  332  defined in the extension element  300 . The method can further comprise moving the extension element  300  along the axis  301  of the extension element bore  231  by operation of the locking actuator  250 . The method can further comprise resting a one of the end accessory  400  and the pad  450  against the user. The method can further comprise securing the adjustable firearm stock  200  tightly to the firearm  100  such that the adjustable firearm stock  200  cannot move with respect to the firearm  100  at any point during use except when the adjustable firearm stock  200  is being adjusted. 
     One should note that conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain aspects include, while other aspects do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more particular aspects or that one or more particular aspects necessarily comprise logic for deciding, with or without user input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular aspect. 
     It should be emphasized that the above-described aspects are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the present disclosure. Any process descriptions or blocks in flow diagrams should be understood as representing modules, segments, or portions of code which comprise one or more executable instructions for implementing specific logical functions or steps in the process, and alternate implementations are included in which functions may not be included or executed at all, may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present disclosure. Many variations and modifications may be made to the above-described aspect(s) without departing substantially from the spirit and principles of the present disclosure. Further, the scope of the present disclosure is intended to cover any and all combinations and sub-combinations of all elements, features, and aspects discussed above. All such modifications and variations are intended to be included herein within the scope of the present disclosure, and all possible claims to individual aspects or combinations of elements or steps are intended to be supported by the present disclosure.