Patent Publication Number: US-10788287-B2

Title: Adjustable stock for firearm

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of priority to U.S. Provisional Application No. 62/578,062 filed Oct. 27, 2017; the entirety of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     The present invention generally relates to firearm stocks, and more particularly to an adjustable buttstock for a firearm that provides adjustment to the length of pull of the firearm and position of an adjustable cheek rest. 
     There are many types of rifle buttstocks that allow the user to make adjustments to the length of pull and cheek rest height to improve the fit of the rifle to the individual user. Many different methods are used to secure and release the moving pieces. Some stocks require the loosening and tightening of nuts and bolts to change positions. This can create a very solid stock with a high amount of adjustability, but making adjustments in the field can be difficult and time consuming. 
     Other stocks use a threaded jackscrew type mechanism, to raise and lower the cheek rest, or move the butt stock length. These require no tools and can be moved in small increments, but can be time consuming to make large adjustments, and usually allow a small amount of movement between the parts. 
     Another method uses a notched adjustment rod in combination with a spring loaded locking button. Pressing the button releases the notched rod, allowing the butt pad, or cheek rest, to be moved to a different position, where the spring loaded button will re-engage the notch. These adjustments are easy to make, but also allow a small amount of movement between parts. 
     Some stocks just use thumb nuts or bolts to clamp the cheek rest at a given position. These are inexpensive and easy to operate, but are also prone to loosening and moving out of position. Several stocks use cam levers to retain a position, but they may still require tools, or multi-handed adjustment methods to properly set the cam tension. 
     An improved adjustable stock design is desired. 
     SUMMARY 
     The present disclosure provides an adjustable rifle stock, more particularly a buttstock assembly, that uses a single locking mechanism to secure the movable components of the buttstock assembly into position on a unitary chassis. The movable components of the buttstock assembly comprise a butt pad assembly adjustable in longitudinal (axial) position and a cheek rest adjustable in both longitudinal and vertical position. The buttstock assembly thus provides length of pull adjustment features and cheek rest adjustment features allowing a user to highly customize the buttstock for comfort and fit to accommodate different physiques and preferences. 
     In one embodiment, the locking mechanism may comprise a spring-biased cam lever assembly changeable between locked and unlocked states or positions. The cam lever assembly includes a pivotably mounted cam lever movable between a release position in which the cam lever assembly is in a locked state, and at least one locking position in which the cam lever assembly is in the unlocked state. The cam lever assembly described herein is more rigid and less likely to unintentionally move from the set locked position either due to vibrations generated by discharging the firearm, or by accidental contact with the user or other object during handling. In one embodiment, a double-acting cam lever and tool free adjustment methods are disclosed that make the cam lever easier to operate by the user with a single hand and provides two different locking positions of the cam lever which accommodates both short and long stock configurations without interference from the handle. 
     The adjustable buttstock according to the present disclosure advantageously uses a single triple action cam lever assembly to release and lock the length of pull adjustment (i.e. length of buttstock assembly) and both the cheek rest height and longitudinal position on the firearm. Advantageously, the double-acting cam lever described herein has the benefit of being able to secure a moving part as tight as a wrench installed fastener, but with the ability of being able to adjust it without tools. There are several features that make the cam levers used on the present buttstock different from the prior stocks described above. 
     First, the cam lever is double acting in one embodiment, meaning it provides no camming or locking action in its open center release position, but provides equal displacement of the locking mechanism when pushed in either direction. This beneficially allows the user to locate the cam lever in one of two possible closed locking positions to suit both individual preferences and avoid interference with the other parts of the firearm or accessories depending on the locked positions selected. 
     Second, another notable difference of the two double-acting cam lever presented herein is the method used for adjustment. Like any cam with a relatively hard stop, if the length of the cam rod is not set precisely, the cam will either remain loose when closed, or be too tight to require excessive force to move it into the closed position. By contrast in the present invention, easy tool-free adjustment is enabled through the combination of the spring loaded cam lever, and unique detent finger nut and ribbed washer as further described herein. 
     In one respect, an adjustable stock assembly for a firearm comprises: a longitudinal axis; a chassis comprising a main body configured for mounting a receiver and an axially elongated rear mounting extension extending rearwardly from the main body; a butt pad assembly slideably coupled to the rear mounting extension, the butt pad assembly slideable between a plurality of axial positions on the rear mounting extension for adjusting a length of pull of the firearm; a cheek rest slideably coupled to the rear mounting extension, the cheek rest slideable between a plurality of vertical positions on the rear extension; and a locking mechanism coupled to the rear mounting extension and changeable between a locked and unlocked position, the locking mechanism configured to simultaneously lock both the butt pad assembly in one of the axial positions and the cheek rest in one of the vertical positions respectively. 
     In another respect, an adjustable stock assembly for a firearm comprises: a longitudinal axis; a chassis comprising a main body configured for mounting a receiver and an axially elongated rear mounting extension extending rearwardly from the main body; a cam lever assembly mechanically coupled to the rear mounting extension, the cam lever assembly comprising a cam lever pivotably movable between a locking position and a release position; the cam lever assembly further comprising a pair of spring-biased clamping blocks coupled to the rear mounting extension, the clamping blocks laterally movable together and apart via operation of the cam lever between a closed position and an open position; a butt pad assembly comprising an elongated butt pad and an adjustment rail protruding axially forward from the butt pad into a longitudinal cavity of the rear mounting extension of the chassis, the adjustment rail received between the clamping blocks and slideable between a plurality of axial positions for adjusting a length of the butt pad; the clamping blocks when in the closed position lockingly engaging the adjustment rail in one of the axial positions, and when in the open position allowing the adjustment rail to slide axially relative to the rear mounting extend between the axial positions; and a cheek rest slideably mounted to the rear mounting extension, the cheek rest slideable between a plurality of vertical positions on the rear extension; the cam lever assembly operable to simultaneously lock both the butt pad assembly and cheek rest in one of the axial positions and vertical positions respectively. 
     In another respect, an adjustable stock assembly for a firearm, the stock comprises: a longitudinal axis; a chassis configured for mounting a receiver thereto and comprising an axially elongated rear mounting extension extending rearwardly from the main body; a locking mechanism slideably coupled to the rear mounting extension and changeable between a locked and unlocked position, the locking mechanism movable between a plurality of first longitudinal positions on the rear mounting extension; a butt pad assembly slideably mounted to the rear mounting extension, the butt pad assembly slideable between a plurality of second longitudinal positions on the rear mounting extension for adjusting a length of pull of the firearm; a cheek rest mounted to the locking mechanism, the cheek rest slideable with the locking mechanism between the plurality of first longitudinal positions on the rear extension; the locking mechanism configured to simultaneously lock both the butt pad assembly in one of the second longitudinal positions and the cheek rest in one of first longitudinal positions. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of the exemplary embodiments will be described with reference to the following drawings where like elements are labeled similarly, and in which: 
         FIG. 1  is a longitudinal side view of one embodiment of a firearm with a stock including an adjustable buttstock assembly according to the present disclosure; 
         FIG. 2  is a top perspective view of the stock of  FIG. 1 ; 
         FIG. 3  is a bottom perspective view thereof; 
         FIG. 4  is a right lateral side view thereof; 
         FIG. 5  is a left lateral side view thereof; 
         FIG. 6  is a top view thereof; 
         FIG. 7  is a bottom view thereof; 
         FIG. 8  is front view thereof; 
         FIG. 9  is a rear view thereof; 
         FIG. 10  is a longitudinal cross-sectional view thereof; 
         FIG. 11  is an enlarged detail of the rear end portion of the stock from  FIG. 10 ; 
         FIG. 12  is a right rear perspective view of the buttstock assembly showing a locking mechanism in a first locked position; 
         FIG. 13  is a right rear perspective view thereof showing the locking mechanism in an unlocked position; 
         FIG. 14  is a right rear perspective view thereof showing the locking mechanism in a second locked position; 
         FIG. 15  is a left rear perspective view thereof; 
         FIG. 16  is an exploded right rear perspective view of the buttstock assembly and locking mechanism; 
         FIG. 17  is a right perspective view showing the locking mechanism partially assembled to the buttstock; 
         FIG. 18  is a right front perspective view showing the locking mechanism in a lock position with cam lever in a locking position; 
         FIG. 19  is an enlarged detail from  FIG. 18 ; 
         FIG. 20  is a right front perspective view showing the locking mechanism in a lock position with cam lever in a release position; 
         FIG. 21  is an enlarged detail from  FIG. 20 ; 
         FIG. 22  is a forward-looking rear transverse cross-sectional view of the buttstock assembly showing the locking mechanism in a locked position with cam lever in a locking position; 
         FIG. 23  is an enlarged detail from  FIG. 22 ; 
         FIG. 24  is a forward-looking rear transverse cross-sectional view of the buttstock assembly showing the locking mechanism in an unlocked position with cam lever in a release position; 
         FIG. 25  is an enlarged detail from  FIG. 23 ; 
         FIG. 26  is a top longitudinal cross-sectional view of the buttstock assembly showing the locking mechanism in a locked position with cam lever in a locking position; 
         FIG. 27  is an enlarged detail from  FIG. 26 ; 
         FIG. 28  is a top longitudinal cross-sectional view of the buttstock assembly showing the locking mechanism in an unlocked position with cam lever in a release position; 
         FIG. 29  is an enlarged detail from  FIG. 28 ; 
         FIG. 30  is a left front perspective view of the butt pad assembly of the buttstock; 
         FIG. 31  is a right front perspective view thereof; 
         FIG. 32  is a left side view thereof; 
         FIG. 33  is front view thereof showing an I-shaped adjustment rail of the butt pad assembly; 
         FIG. 34  is a rear end view of the stock chassis showing the rear end of a mounting extension for coupling the butt pad assembly and cheek rest thereto; 
         FIG. 35  is a right side view of the mounting extension of the stock; 
         FIG. 36  is transverse cross section thereof showing an I-shaped longitudinal cavity of the rear mounting extension; 
         FIG. 37  is a first perspective view of a clamping block of the locking mechanism; 
         FIG. 38  is a second perspective view thereof; 
         FIG. 39  is a right perspective view of the cheek rest; 
         FIG. 40  is a left perspective view thereof; 
         FIG. 41  is an enlarged detail taken from  FIG. 40 ; 
         FIG. 42  is a perspective view of a detent finger nut for adjusting tension in the locking mechanism; 
         FIG. 43  is a first perspective view of a toothed locking washer of the locking mechanism; 
         FIG. 44  is a second perspective view thereof; 
         FIG. 45  is a perspective view of an alternative toothless locking washer of the locking mechanism; and 
         FIG. 46  is an enlarged detail of an alternative toothless cheek rest usable with the toothless washer of  FIG. 45 . 
     
    
    
     All drawings are schematic and not necessarily to scale. Parts given a reference numerical designation in one figure may be considered to be the same parts where they appear in other figures without a numerical designation for brevity unless specifically labeled with a different part number and/or described herein. Parts described herein with respect to certain figures may also appear in other figures in which they may be numbered or unnumbered unless otherwise noted herein. Furthermore, a general reference to a whole figure number (e.g.  FIG. 6 ) which may include multiple alphabetic subparts (e.g.  FIGS. 6A, 6B , etc.) shall be construed as a reference to all of the subparts unless specifically noted otherwise. 
     DETAILED DESCRIPTION 
     The features and benefits of the invention are illustrated and described herein by reference to exemplary embodiments. This description of exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. Accordingly, the disclosure expressly should not be limited to such exemplary embodiments illustrating some possible non-limiting combination of features that may exist alone or in other combinations of features. 
     In the description of embodiments disclosed herein, any reference to direction or orientation is merely intended for convenience of description and is not intended in any way to limit the scope of the present invention. Relative terms such as “lower,” “upper,” “horizontal,” “vertical,”, “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivative thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the apparatus be constructed or operated in a particular orientation. Terms such as “attached,” “affixed,” “connected,” “coupled,” “interconnected,” and similar refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. 
     The term “action” which may be mentioned is used herein in its conventional sense in the firearm art as meaning the mechanism that loads and ejects shells into/from the firearm and opens and closes the breech (i.e. the area in the receiver between an openable/closeable breech face on the front of the bolt and the rear face of the barrel chamber). 
     Referring initially to  FIGS. 1-16 , a firearm  20  in the form of a rifle is shown including a stock  20  having a multi-adjustable buttstock assembly  30  according to the present disclosure. Firearm  20  may be any type of long gun, including without limitation a rifle or a shotgun. In one non-limiting example illustrated, the firearm  20  may be a manually operated bolt action rifle. More particularly in one embodiment, the rifle may be a bolt action rimfire rifle. The stock  20  however may be used with centerfire rifles in some embodiments. Accordingly, the stock  20  is not limited in its possible applications. 
     The bolt action firearm  20  generally includes a receiver  21 , a trigger actuated fire control assembly  22  mounted in the receiver and operable to discharge the firearm, a barrel  23  supported by the receiver, optionally a handguard  24  enclosing and circumscribing at least part of the length of the barrel, and stock  26 . Stock  26  supports the receiver and fire control assembly in one embodiment. The barrel  23  includes an open front muzzle end  23   a  and an open rear breech end  23   b  (obscured beneath the handguard) coupled to a front end  21   a  of the receiver  21  in any suitable manner. Handguard  24  may similarly be coupled to a front end of the receiver and/or other portions of the firearm. 
     The firearm  20  defines a longitudinal axis LA and axial direction coinciding with the centerline of the barrel  23  and its longitudinal bore formed therein between the muzzle and breech ends  23   a ,  23   b  that defines a projectile pathway in a known manner. 
     The receiver  21  supports an axially movable bolt  25  (seen through the receiver&#39;s cartridge ejection port in  FIG. 1 ). Bolt  25  may include a laterally extending bolt handle  25   a  for selectively forming a closed or open breech. The bolt  25  is manually and slideably moveable forward/rearward in an axially extending internal cavity of receiver  21  and includes a firing pin (not shown) for detonating a chambered cartridge in the rear breech end  23   b  of the barrel  23  that defines the chamber; all of which is well understood by those skilled in the art without further elaboration. 
     In one embodiment, stock  26  includes a forward mid-stock  27  and a rearward adjustable buttstock assembly  30  slideably mounted to the mid-stock. The mid-stock  27  may be considered to define an axially elongated one-piece unitary chassis which supports the receiver  21  and adjustable buttstock assembly  30 . The buttstock assembly  30  in turn comprises an adjustable butt pad assembly  33  and cheek rest  32 . Mid-stock  27  comprises a main body  27 - 1  defining a longitudinally-extending and upwardly open receiver-bedding cavity  28  for mounting the receiver  21  thereto and for housing the trigger-actuated fire control mechanism  22 . The receiver may be partially received within cavity  28 , wherein the upper portion of the receiver remains exposed and the lower portion is nested within the cavity in typical fashion. Any suitable method may be used to mount the receiver  21  to the main body  27 - 1  of the mid-stock, such as for example fasteners (e.g. screws, bolts, pins, etc.). A downwardly open magazine well  27 - 2  is defined by the main body  27 - 1  of the mid-stock for receiving a magazine well insert and ammunition magazine therein (not shown). In one embodiment, mid-stock  27  may also comprise a downwardly extending pistol grip  29  in some embodiments to facilitate handling the firearm. Pistol grip  29  may be integrally formed with the mid-stock as a unitary structural part thereof, or alternatively may be a discrete separate part fastened to the mid-stock such as via one or more fasteners  29 - 1  (see, e.g.  FIG. 10 ). Mid-stock  27  further includes a trigger guard  27 - 3  in one embodiment. 
     In one embodiment, mid-stock  27  may be formed of a non-metallic like a polymeric material such as glass reinforced nylon or other plastics. Mid-stock  27  may therefore be made by a suitable plastic molding process, such as injection molding. Other non-metallic and metallic materials may be used for the mid-stock. 
     Mid-stock  27  further comprises a rearwardly and axially extending mounting extension  31  for mounting buttstock assembly  30  thereto in an adjustable manner. Mounting extension  31  is an axially elongated structure having a length in one embodiment which forms greater than 30% of the total length of the mid-stock  27 , and in some embodiments greater than 40% of the mid-stock total length. Mounting extension  31  has a greater length than its height or width. In a preferred but non-limiting embodiment, the mounting extension  31  may be formed as an integral unitary structural part of the monolithic mid-stock main body  27 - 1 , which facilitates formation of the entire chassis with mounting extension by injection molding in a single mold for economies of fabrication. The mounting extension  31  provides a common support and mounting platform for the adjustable butt pad assembly  33  and cheek rest  32 , as further described herein. 
     In one embodiment, the rear mounting extension  31  comprises an upper section  31 - 1  extending rearward from and contiguous with the main body  27 - 1  of the mid-stock  27 , and a lower section  31 - 2  which defines a terminal rear end  31 - 3  of the mounting extension. Each of the upper section  31 - 1  and lower section  31 - 2  are generally straight and extend axially parallel to longitudinal axis LA. Upper and lower sections  31 - 1 ,  31 - 2  lie in two different horizontal planes and are vertically offset from one another. An angled transition section  39  may be formed between the upper and lower sections giving the mounting extension  31  a somewhat angular S-shaped configuration in one embodiment as shown. The foregoing arrangement locates the lower section  31 - 2  of mounting extension  31  below the upper section  31 - 1 , main body  27 - 1  of mid-stock  27 , and longitudinal axis LA. The lower section  31 - 1  defines a horizontal buttstock assembly mounting axis MA, which is therefore vertically offset from the horizontal centerline of the main body and longitudinal axis LA. When the butt pad of the buttstock assembly  30  is positioned against a user&#39;s shoulder, the offset advantageously elevates the barrel to the proper height in alignment with the user&#39;s line of sight for aiming. 
     In one configuration, the chassis mounting extension  31  may have a generally rectangular overall configuration in transverse cross section. The rear end  31 - 3  of the mounting extension  31  may optionally have rounded corners. Mounting extension  31  defines an axially elongated and rearwardly open internal longitudinal cavity  40  for mounting buttstock assembly  30  thereto. Each lateral side  42  of mounting extension  31  may comprise an outwardly open window  41 . Windows  41  may be axially elongated in one embodiment as shown and extend for a majority of the length of mounting extension  31 . The windows  41  facilitate mounting of the slideable locking system used to mount the butt pad assembly  33  and cheek rest  32  to the mounting extension, as further described herein. 
     Buttstock assembly  30  comprised of the butt pad assembly  33  and cheek rest  32  may have a variety of configurations; one non-limiting example being shown in the figures. In one non-limiting embodiment, as illustrated, the buttstock assembly  30  may be a non-folding type structure. 
     The components of the buttstock assembly  30  and locking mechanism are seen in the exploded view of  FIG. 16 . Buttstock assembly  30  in one implementation may include a vertically and longitudinally/axially adjustable cheek rest  32  and a longitudinally/axially adjustable butt pad assembly  33 . Butt pad assembly  33  is configured for placement against the user&#39;s shoulder when aiming the firearm held in a ready-to-fire position to acquire a target. The butt pad assembly allows the length of the buttstock (i.e. length of pull) to be adjusted to accommodate different users and preferences. In a preferred but non-limiting embodiment, the buttstock includes both an adjustable cheek rest and butt pad assembly each adjustable via a single adjustment mechanism, as further described herein. In other less preferred but possible satisfactory embodiments, a non-adjustable stationary cheek rest  32  may be provided which is fixedly attached to the rear mounting extension  31  of the chassis. 
     Referring generally to  FIGS. 1-16 , butt pad assembly  33  includes a vertically elongated butt or recoil pad  34  attached to a forward recoil pad base plate  35 . Recoil pad  34  may be attached to base plate  35  by any suitable method, including without limitation threaded fasteners  36  as shown and/or adhesives, friction or interference fit, interlocking features, etc. The recoil pad base plate  35  may be substantially rigid and vertically elongated in structure to absorb recoil forces generated by firing the firearm  20 , which are then transmitted through the base plate to the recoil pad  34  configured to rest against the user&#39;s shoulder. Recoil pad base  35  may be made of a metallic or preferably non-metallic material in one embodiment such as a hard plastic to reduce weight. The recoil pad  34  preferably is made of a deformable cushioned energy absorbing material such as without limitation an elastomeric polymer, rubber, closed or open cell foam, memory foam, gel, or combinations of these material and others. Recoil pad  34  in other embodiments may be made of a substantially rigid material such as plastic or other. Accordingly, the invention is not limited by the construction of the butt pad or recoil plate. 
     It should be noted that various parts of the buttstock assembly described herein may be made of any variety of suitable materials including glass reinforced or non-reinforced polymers, metals, composite materials, fiberglass, wood, and combinations thereof as some non-limiting examples. The material selection will be dictated in part by functional and service conditions as well as weight saving considerations. Accordingly, the invention is not limited by material selection for the butt pad components. 
     The buttstock assembly adjustment and locking features of the adjustable butt pad assembly  33  will now be described with initial reference to  FIGS. 10-32 .  FIGS. 30-32  show the butt pad assembly  33  alone. 
     Butt pad assembly  33  includes an axial position adjustment feature generally comprised of an upper adjustment rail  50  which allows the length of pull to adjusted per the user&#39;s preferences. A lower accessory rail  51  may optionally be provided in some embodiments for mounting various accessories to the buttstock assembly. Accessory rail  51  plays no role in adjusting or locking the length of pull of the butt pad assembly  33 . Upper adjustment and lower accessory rails  50 ,  51  extend or protrude longitudinally and axially forward from the butt pad assembly  33  (i.e. parallel to longitudinal axis LA). Rails  50 ,  51  are rigidly and fixedly attached mounted to the recoil pad base plate  35  which prevents relative movement of the rails with respect to the butt pad assembly. Any suitable means or combination of means may be used to couple the rails  50 ,  51  to the recoil pad base plate  35 , including without limitation threaded or non-threaded fasteners, pins, adhesives, welding, interference fits, interlocking features, etc. 
     In one preferred embodiment, the axially elongated rails  50 ,  51  are integrally formed as a unitary structural part of the monolithic recoil pad base plate body, which may be formed of molded plastic in an example construction. The rails  50 ,  51 , base plate  35 , and butt pad  34  provide a separate structurally self-supporting assembly which is then coupled to the mounting extension  31  of the stock chassis. 
     The adjustment and accessory rails  50 ,  51  may be spaced vertically apart and arranged parallel to each other and longitudinal axis LA. The rails  50 ,  51  may lie in the same vertical plane along the centerline of the firearm  20  which includes the longitudinal axis LA. The upper adjustment rail  50  may be located between the top heel and bottom toe of the butt pad  34 , but more proximate to the heel. Accordingly, upper adjustment rail  50  is oriented parallel to longitudinal axis LA but spaced below the axis. The lower accessory rail  51  is disposed more proximate the bottom toe of the butt pad  34 . 
     The upper adjustment rail  50  and lower accessory rail  51  may have any suitable transverse cross-sectional shape and length. The accessory rail may be shorter in length than the adjustment rail in one embodiment. In the non-limiting embodiment illustrated, the rails  50 ,  51  may have different cross-sectional shapes and side profiles as shown. Accessory rail  51  may include a laterally open through hole  51 - 1  and a section of accessory rail  51 - 2  in one to facilitate mounting accessories. Adjustment rail  50  includes an axially elongated longitudinal slot  50 - 1  for passage of the coupling shaft  103  of the cam lever assembly  100  therethrough. The longitudinally-extending slot allows the adjustment rail  50  to slide forward and rearward in the longitudinal cavity  40  of the chassis rear mounting extension  31 . 
     In one embodiment, the adjustment rail  50  may have an I-shaped transverse cross-sectional configuration (see, e.g.  FIG. 33 ) tantamount to a structural I-beam for mechanical strength to resist rotational twisting or axial bending of the rail and butt pad assembly  33  attached thereto. The I-shaped cross section may be asymmetrical in one embodiment (see, e.g.  FIG. 33 ) with the teeth  66  on the laterally shorter side of the mounting extension adjustment rail  50  (right side in  FIG. 33 ). As shown in  FIG. 27 , the teeth  66  on the adjustment rail  50  are laterally offset so that the same toothed clamping blocks  60  can be used on both sides. When clamped, the clamping block teeth  65  on the right side have clearance so clamping block teeth  64  only clamp on teeth  67  of the extension rail  31 , and the clamping block teeth  64  on the left side have clearance so clamping block teeth  65  only clamp on the mounting extension adjustment rail teeth  66 . This arrangement allows the clamping blocks  60  and cheek rest  32  mounted thereto to move independently of the butt pad assembly  33  along the longitudinal axis LA in axial position, while still providing a robust clamping method for the assembly. 
     The butt pad assembly  33  is supported by the rail  50  in a cantilevered manner from the chassis rear mounting extension  31  as illustrated. Other structurally robust cross-sectional shaped may be used in other embodiments, such as T-shaped cross sections or simply rectangular/square cross-sectional shapes. Preferably, the adjustment rail  50  has a polygonal shape in lieu of a circular shape to prevent rotation relative to the rear mounting extension  31  since the present butt pad support system utilizes a single cantilevered point of support and mounting axis MA defined by adjustment rail  50 , as further described herein. 
     The upper adjustment rail  50  is slideably supported and axially received in the rearwardly open longitudinal cavity  40  of the mid-stock mounting extension  31 . The rail  50  is slideable between a plurality of axial positions relative to the rear mounting extension  31  to adjust the length of pull of the butt pad assembly  33 . The axial positions may be indexed positions in one embodiment formed by a meshed arrangement of interlocking teeth, as further described herein. Longitudinal cavity  40  preferably may be complementary configured to the polygonal transverse cross section to the adjustment rail  50  of the butt pad assembly. This creates mutual but sliding engagement therebetween which prevents the adjustment rail  50  with butt pad assembly  33  from angularly twisting relative to the mounting extension  31 . In one embodiment, the cross sections of the cavity  40  and adjustment rail  50  have an asymmetrical I-shaped configuration (see  FIGS. 33-36 ). 
     A locking mechanism mounted on chassis rear mounting extension  31  is provided which allows the user to secure and lock the adjustment rail  50  to the rear mounting extension in a plurality of selected axial positions relative to the extension. Accordingly, the butt pad assembly  33  is slideable between and lockable in a plurality of preferably indexed axial positions on the rear mounting extension for adjusting a length of pull of the firearm. In one embodiment, the cheek rest  32  is also longitudinally adjustable being slideable between and lockable in a plurality of preferably indexed axial positions on the rear mounting extension  31  by the same locking mechanism. The cheek rest  32  is further vertically adjustable being slideable between and lockable in a plurality of preferably indexed vertical positions on the mounting extension  31  to adjust the height of the cheek rest. The same locking mechanism is configured and operable to lock the cheek rest  32  in a selected vertical position relative to the mounting extension  31 . 
     Advantageously, the foregoing sole or single locking mechanism is configured to accomplish all of the above locked positions of the butt pad assembly  33  and cheek rest  32  simultaneously when the locking mechanism is in a locked position. This allows creation of an overall compact and lightweight buttstock assembly  30  operated by one locking mechanism. This contrasts to prior designs which generally rely on a separate locking mechanism for the length of pull adjustment and one for the cheek rest vertical adjustment. Furthermore, such prior designs generally do not provide axial adjustment of the cheek rest. 
     In one embodiment, the locking mechanism may comprise without limitation a spring-biased cam lever assembly  100  having a cam lever  101  movable between an open position in which the butt pad assembly  33  and cheek rest  32  are locked in position on the rear mounting extension  31  of the chassis (defined by mid-stock  27 ), and a closed position in which the butt pad assembly and cheek rest are slideable relative to the rear mounting extension. The cam lever assembly  100  further comprises a pair of uniquely configured clamping blocks  60  configured to selectively and lockingly engage the rear mounting extension  31  and adjustment rail  50  of the butt pad assembly  33 . In one embodiment, the cam lever assembly  100  may comprise a double-acting cam lever. These components and their interaction are further described below. 
     Referring initially to  FIGS. 16-29 , cam lever assembly  100  generally comprises an elongated cam lever  101 , transversely extending coupling shaft  103 , a pair of locking washers  104 , a finger nut  106 , an opening spring  107 , and a pair of clamping blocks  60 . With additional reference to  FIGS. 43-44 , the washers  104  provide vertically oriented lateral bearing surfaces  104 - 2  on each side of the mounting extension  31  for the cam head  109  of cam lever  101  and finger nut  106  respectively to bear against when the cam lever assembly  100  is assembled to clamping blocks on the mounting extension. Washers  104  each include a central through opening  104 - 1  for insertion of coupling shaft  103  therethrough and include substantially flat bearing surfaces  104 - 2  on the outward facing side. Opening  104 - 1  may be a vertically elongated slot. In one embodiment, washers  104  may be generally rectilinear (e.g. rectangular or square) shaped as shown (see, e.g.  FIGS. 43-44  showing the washers in isolation). The washers  104  are preferably made of metal, but non-metallic durable washers made of other materials such as polymers may be used. 
     The coupling shaft  103  extends laterally between and through the pair of clamping blocks  60  slideably disposed on mounting extension  31  of mid-stock  27  to operably couple the blocks together. One clamping block  60  each is disposed on each lateral side  42  of the mounting extension  31  and positioned to operably engage the chassis mounting extension  31  and butt pad assembly adjustment rail  50 , as further described herein. In one embodiment, the coupling shaft  103  may be in the general form of an eye bolt having a threaded portion  103   a  on one end and a circular opening  103   b  (“eye”) at the other enlarged end. Other configurations of coupling shafts may be used. 
     Cam lever  101  is shown and described as mounted on the right side of the cam lever assembly  100  and the right clamping block  60  in the present example; however, in other embodiments the cam lever may be mounted instead on the left clamping block  60  and will function in the same manner. This mounting may be preferable for left-handed firearm users or for right folding stocks. The cam lever  101  is therefore ambidextrous and may be positioned on either the right or left lateral side of the stock  26  to suit the user&#39;s preferences. 
     Cam lever  101  includes an elongated operating handle  108  and a cam head  109  at one end of the handle. Cam head  109  may have an oblong shape and comprises two diametrically opposing arcuate locking surfaces  110   a ,  110   b  and a flat release surface  111  disposed therebetween. The locking surfaces are on the short sides of the cam head. The cam head  109  may be a bifurcated structure forming two spaced apart halves defining a slot  112  therebetween. Slot  112  receives the enlarged end  103   c  of coupling shaft  103  with opening  103   b . The opening  103   b  is concentrically aligned with mating holes formed in each half of the cam head  109  which all receive pivot pin  102  therethrough that pivotably couples the coupling shaft and cam lever  101  together. Pin  102  defines a pivot axis of the cam lever  101 . To provide a smooth but tight fit between the coupling shaft  103  and cam head  109 , the enlarged end of the coupling shaft may be flattened on each side to mate with corresponding flat interior surfaces of the cam head on each side of the slot  112 . This fit allows rotation of the cam lever  101  without excessive play or wobbling which is undesirable. 
     The coupling shaft  103  extends transversely between the right and left sides of the mounting extension  31  of the mid-stock  27  and through the pair of clamping blocks  60 . Starting from the right side of the firearm, coupling shaft  103  goes from the cam head  109  through the right washer  104 , then through a laterally open central hole in the right clamping block  60 , then through the longitudinal cavity  40  of mounting extension  31  via the laterally open pair of lateral windows  41 , through the laterally open central hole of the left clamping block  60 , through the left washer  104  so that the threaded end  103   a  of the coupling shaft protrudes outwards beyond the left washer and is exposed. The threaded end  103   a  of coupling shaft  103  rotatably receives finger nut  106  to adjust the tension in the cam lever assembly  100 . The opening spring  107  is disposed around and between the clamping blocks  60  to bias the blocks apart away from the mid-stock mounting extension  31 . 
     Spring  107  may be a helical compression spring in one embodiment; however, other type springs may be used. The spring  107  is positioned around the coupling shaft  103  between clamping blocks  60 . The shaft  103  extends transversely/laterally through the longitudinal cavity  40  and windows  41  of the mid-stock mounting extension  31 . One end of the spring abuts left clamping block  60  and the other end abuts the right clamping block (see, e.g.  FIG. 27 ). 
       FIGS. 37-38  shows the uniquely configured clamping block  60  in isolation, which provides dual duty to both clamp and lock the butt pad assembly  33  in axial position and lock the clamping block itself in axial position on the chassis (mid-stock) rear mounting extension  31 . Clamping block  60  may have a rectilinear square or preferably rectangular body in one embodiment including a central opening or hole  61  for passage of the cam lever assembly coupling shaft  103  therethrough. The block body comprises a base portion  62  having a first set of serrated teeth  64  arranged for lockingly engaging rear mounting extension  31  of the mid-stock  27  (chassis), and a raised portion  63  having a second set of serrated teeth  65  arranged for lockingly engaging the forwardly extending adjustment rail  50  of the butt pad assembly  33 . The base portion  62  has a greater surface area than the raised portion  63 ; the latter of which may be centered on the base portion as shown. The first and second sets of teeth  64 ,  65  lie in different flat planes or levels, and are therefore offset from each other. The sets of serrated teeth  64 ,  65  may comprise parallel rows of elongated teeth which assume a vertical orientation when the clamping blocks  60  are mounted on the chassis rear mounting extension  31 . In one embodiment, as shown, each of the sets of teeth  64  and  65  may be oriented in the same direction and are parallel to each other. 
     The smaller raised portion  63  of each clamping block  60  is configured and dimensioned to project inwards through longitudinally-extending lateral windows  41  in the rear mounting extension  31  and into the longitudinal cavity  40 . The teeth  65  on raised portion  63  lockingly engage a mating set of complementary configured serrated teeth  66  formed on the left lateral side  50 - 3  of the butt pad assembly adjustment rail  50  (see also  FIGS. 30 and 32 ) when the cam lever assembly  100  is in the locked position. This fixes the butt pad assembly in a user-selected axial position. The meshed teeth  65 ,  66  provided indexed mounting positions. The teeth  66  on the adjustment rail  50  may be vertically oriented and extend axially along a majority of the length of the adjustment rail forming an axially elongated linear track of teeth. When the cam lever assembly  100  is in an unlocked position, the adjustment rail  50  is slideable through the longitudinal cavity  40  of the rear mounting extension  31  to allow adjustment of the firearm length of pull. The opposite lateral side  50 - 2  of the adjustment rail  50  may be plain without teeth in one embodiment (see, e.g.  FIG. 31 ), thereby providing clearance between the C 1  between the adjustment rail  50  and teeth  65  on raised portion  63  of the clamping block  60 . This allows the butt pad assembly  33  to be adjusted in axial position independently of the axial position of the clamping blocks  60  and cheek rest  32  mounted thereto. 
     The larger base portion  62  of each clamping block  60  by contrast is intentionally dimensioned taller in height than the height of the mounting extension lateral windows  41  to remain outside thereof. Teeth  64  lockingly engage a mating set of complementary configured serrated teeth  67  formed on the right lateral side  42  of the mid-stock mounting extension  31  when the cam lever assembly  100  is in the locked position. This fixes the clamping blocks  60  in a user-selected axial position on the chassis, thereby in turn setting the longitudinal/axial position of the cheek rest  32  mounted to clamping blocks, as further described herein. The meshes teeth  64  and  67  provided indexed mounting positions. The teeth  67  on the mounting extension may be vertically oriented and extend axially along the length of the extension rail. In one embodiment, teeth  67  may be omitted on the left lateral side  42  of the extension  31 . The teeth  67  on the right lateral side  42  of mounting extension  31  may be arranged in two parallel rows or tracks of teeth  66 ; one each above and below the lateral windows  41  (see, e.g.  FIG. 17 ). The teeth  67  may further continue around the front and rear ends of the window  41  as shown. In one embodiment, the teeth  67  may be formed within longitudinal recesses  43  surrounding the windows  41  as shown. When the cam lever assembly is in an unlocked position, the clamping blocks  60  with cheek rest  32  mounted thereto are slideable along the chassis rear mounting extension  31  to allow adjustment of the cheek rest longitudinal position. 
     It bears noting that the foregoing mating sets of teeth provide discrete indexed adjustment positions of the butt pad assembly  33  and the clamping blocks  60 /cheek rest  32  relative to the rear mounting extension  31  of the mid-stock chassis. In other possible acceptable embodiments, however, the teeth on the clamping blocks  60 , adjustment rail  50 , and mounting extension  31  may be omitted and the compressive clamping force produced by cam lever assembly  100  may relied upon alone to retain the selected axial positions via frictional engagement between the slideable parts. 
     The opening spring  107  biases the clamping blocks  60  laterally apart which defines the unlocked position of the cam lever assembly  100  in which the blocks do not lockingly engage the chassis mounting extension  31  or adjustment rail  50  of the butt pad assembly  33 . This allows the clamping blocks  60  to slide axially forward and rearward relative to the mounting extension  31  for adjusting the axial position of the blocks relative to the extension. This also allows the adjustment rail  50  to slide axially forward and rearward for adjusting the axial position (length of pull) of the butt pad assembly  33 . 
     The clamping blocks  60  are laterally movable together and apart via operation of the cam lever  101  between an inward or closed locked position and an outward or open unlocked position. In the locked position, the clamping blocks  60  are forced inwards and together by the lever mechanism to compressively and lockingly engage the mounting extension  31  and adjustment rail  50  for locking the clamping blocks in axial position. When locked in position, the clamping blocks  60  thus cannot slide forward/rearward. In the unlocked position, the clamping blocks  60  are forced apart by the opening spring  107  to at least partially disengage and allow adjustment in axial position of the cheek rest  32  and butt pad assembly  33 . 
     Operation of the cam lever assembly  100  for adjusting the length of pull will now be briefly described with initial general reference to  FIGS. 18-29  and the following process or method. The double-acting cam lever  101  is pivotably movable from an open center neutral or release position in which the cam lever assembly linkage is loosened (see, e.g.  FIGS. 13, 20, 21, 24, 25, 28 and 29 , to one of two closed diametrically opposed side locking positions in which the cam lever assembly linkage is tightened (see, e.g.  FIGS. 12, 14, 18, 19, 22, 23, 26, and 27 ). The locking positions may be at least 180 degrees apart and the release position is between the locking positions, preferably midway between the locking positions in one embodiment. 
     Beginning with  FIGS. 13, 20, 21, 24, 25, 28 and 29 , the cam lever assembly  100  is shown open with the cam lever  101  in the loosened center release position. In the present non-limiting embodiment, the open center release position of the cam lever  101  is characterized by the operating handle  108  being oriented substantially horizontal and perpendicular to the right lateral side  42  of the mid-stock mounting extension  31  (the term “substantially” recognizing that the lever may be canted slightly to one or the other side of absolute center so long as the locking surfaces  110  of cam head  109  are not positively engaged with the right washer  104  to tension the coupling shaft  103  enough to lock the adjustment rail  50  in axial position). The cam lever assembly  100  is in the unlocked position when the cam lever  101  is in the center release position, in which the upper adjustment rail  50  of butt pad assembly  33  can slide axially between the clamping blocks  60  and through the mid-stock rear mounting extension  31  for adjusting the longitudinal position of the butt pad assembly, or length of pull. The flat release surface  111  of cam head  109  is lightly engaged with the washer  104  (bearing surface  104 - 2 ) when the lever  101  is in the center release position. Placing the cam lever in this center release position allows the clamping blocks  60  to open and spread fully apart (under the biasing action of spring  107 ), thereby moving the clamping blocks  60  apart to the open position for adjusting the length of butt pad assembly  33  (length of pull) and/or the longitudinal position of the clamping blocks  60 /cheek rest  32 . Spring  107  urges the laterally moveable clamping blocks  60  outwards by the maximum amount permitted and limited by prior adjustment and tightening of the finger nut  106 . 
     Because the cam head flat release surface  111  on cam head  109  of the cam lever  101  is closer to the pivot axis of the cam lever  101  defined by pin  102  than either of the two arcuate locking surfaces  110   a ,  110   b  on the cam head, the distance between the release surface  111  and the bearing surface  104 - 2  on locking washer  104  acted upon by lever cam head  109  in this example is the shortest. Therefore, the cam lever  101  is in a slightly loosened condition allowing the biasing spring  107  to laterally displace the clamping blocks  60  outwards and apart slightly enough to disengage the meshed teeth  65 ,  66  and allow the butt pad assembly upper adjustment rail  50  to slide through the clamping blocks. With clamping pressure released on the adjustment rail  50 , the use may slide the butt pad assembly  33  forward or rearward to the desired axial position to shorten or lengthen the buttstock (e.g. length of pull). This contrasts to the tightened or locked condition of the cam lever  101  when either of the two locking surfaces  110   a ,  110 B engage the washer  104 , thereby forcing the clamping blocks  60  laterally inwards to clamp the adjustment rail  50  in axial position. 
     Once the desired length of pull has been reached, the butt pad assembly  33  is ready to be locked into axial position. The user may pivot the cam lever  101  vertically about the horizontal pivot axis (defined by pin  102 ) to either one of the two up or down locking positions shown in  FIGS. 12, 14, 18, 19, 22, 23, 26, and 27  provided by the double-acting cam lever mechanism. In the up or down locking positions, the operating handle  108  of cam lever  101  will either point up or down respectively being oriented either parallel or obliquely to the opposing lateral sides  42  of the chassis rear mounting extension  31  and sides of the cheek rest  32 . 
     When the cam lever  101  is rotated to one of the up or down locking positions, the respective arcuate locking surface  110   a  or  110   b  engages the bearing surface  104 - 2  defined by right locking washer  104 . This pulls the coupling shaft  104  transversely to the right side of the stock towards the cam lever  101  against the outward biasing force of spring  107  acting in a direction to push the clamping blocks  60  apart. The opening spring  107  is compressed as the clamping blocks  60  are drawn together into the closed position. The first set of teeth  65  on each clamping block  60  mesh with the teeth  66  on the butt pad assembly adjustment rail  50  to lock the rail in place. The butt pad assembly  33  is no longer axially movable with respect to the mounting extension  31  and secured in the axial position selected by the user. Simultaneously, the second set of teeth  64  mesh with the teeth  67  on the chassis mounting extension  31  to lock the clamping blocks  60  and cheek rest  32  mounted thereto in axial/longitudinal position on the mounting extension  31 . 
     It bears noting that the same foregoing length of pull adjustment steps are also used to adjust the longitudinal position of the clamping blocks  60  and cheek rest in a similar manner. When the cam lever assembly  100  is unlocked the blocks  60  may be slid forward and rearward to the desired axial position. The cam lever assembly may then be locked in the manner previously described herein to fix the axial position of the clamping blocks (and cheek rest  32  mounted thereto). 
     According to another aspect of the invention, an indexed detent tensioning mechanism is provided by finger nut  106  for adjusting the tension in the cam lever assembly  100 . Referring to  FIG. 42 , finger nut  106  is round and includes a plurality of elongated radially extending recessed detents  106 - 1  formed on the inward facing side of the nut. Even or odd numbers of detents  106 - 1  may be provided. In one embodiment, the detents may be arranged in diametrically opposed pairs. Eight detents  106 - 1  may be provided as one example arrangement; however, more of less detents may be used as appropriate. The detents  106 - 1  may be elongated depressions which extend radially outwards from the threaded central hole  106 - 2  which is threaded onto the exposed threaded end  103   a  of coupling shaft  103  that defines a rotational axis for finger nut  106 . 
     As the finger nut  106  is rotated, detents  106 - 1  alternatingly mate with and selectively engage a protruding linear index rib  120  disposed on left locking washer  104  (see, e.g.  FIG. 43 ). Rib  120  may be vertically oriented and centered on the washer between the front and rear sides. Detents  106 - 1  are circumferentially spaced apart by a suitable angle A 1  selected to provide a plurality of circumferential index positions for tightening the cam lever linkage (e.g. coupling shaft  103 ). 
     In operation, when the cam lever  101  is in one of the two tightened locking positions, the finger nut  106  is held securely in place from loosening by the engagement between the washer index rib  120  and an engaged diametrically opposed pair of detents  106 - 1  (one each on opposite sides of through hole  106 - 2 ) which prevents rotation or loosening of the nut due to vibration when the firearm is fired. The coupling shaft  103  and cam lever  101  assisted by spring  107  apply an inward directed pulling force on the finger nut  106 , thereby maintaining positive engagement of the rib  120  in the detents  106 - 1 . When the cam lever  101  is instead released and pivoted to the opened center release position to loosen the linkage, the opening spring  107  still provide sufficient pressure which holds the washer  105  and finger nut  106  against each other, but clearance is now created sufficient to allow the washer and nut to separate slightly when the nut is turned by the user. 
     The foregoing indexed detent action is useful for setting the tension in the cam lever assembly  100 . If the user closes the cam lever  101  and finds it too loose to operate the clamping blocks  60  properly, the cam lever can be positioned in the center release position and the finger nut can be rotated and tightened in ⅛ turn increments (in the present example with eight detents), with a positive detent felt at each increment by the user. The detent action also advantageously creates an “clicking” noise providing not only a tactile sensation, but an audible signal as well each time a circumferential index position is reached. The cam lever  101  can then be easily reclosed, testing the new setting, and the process can be repeated until the desired tension is achieved. This quick and intuitive adjustment method allows a positive and consistent locking force to be maintained in both closed cam lever locking positions as well as over the wide range of adjustment where part tolerance may allow some variation. 
     The cheek rest  32  adjustment and locking features will now be described. 
     Referring initially to  FIGS. 39-41 , the cheek rest locking mechanism in one embodiment may advantageously utilize the same double-acting cam lever assembly  100  as previously described for the butt pad assembly locking mechanism. Cam lever assembly  100  is thus a triple-acting locking mechanism advantageously operable to lock the butt pad assembly and cheek rest in position via operation of a single cam lever  101  for convenience and compactness. The axial/longitudinal position of cheek rest  32  on the firearm (i.e. rear mounting extension  31  of mid-stock or chassis) is adjustable and lockable in place via operation of the clamping blocks  66  and cam lever assembly  100  in the manner previously described herein with respect to length of pull adjustment. This is because the cheek rest  32  is mounted directly to the clamping blocks  60 , which in turn are slideable in axial/longitudinal position on the chassis rear mounting extension  31 . Height adjustment of the cheek rest  32  is also accomplished using the same cam lever  101 , which is configured to cooperate with height adjustment/indexing features of the cheek rest. 
     Cheek rest  32  has a generally U-shaped body including an upper main portion forming an arcuately curved top  130  and contiguous opposing right and left sidewalls  131  and  132 . The main portion is axially elongated in the direction of the longitudinal axis LA and defines a longitudinal passage  32 - 1 . When cheek rest  32  is in it lowermost adjustment position, the chassis extension rail  31  may partially enter the passage  32 - 1  in some configurations. A pair of bifurcated lateral adjustment legs  136  extends downwardly from the sidewalls  131 ,  132  forming therein a vertical slot  134  have a closed top end and open bottom end. A toothed rack  135  is disposed on each side of the slots  134  forming a pair of horizontally spaced apart toothed racks on each adjustment leg. Each toothed rack  135  comprises a plurality of teeth  137  in a linear or serial arrangement. The toothed racks  135  in each pair are arranged parallel to each other and transversely/perpendicularly to longitudinal axis LA (when the cheek rest  32  is mounted on the chassis rear mounting extension  31 ). In one embodiment, each toothed rack  135  may be recessed within a linear channel  135 - 1  (best shown in  FIGS. 17 and 40 ). 
     In one embodiment, the vertical toothed racks  135  are arranged to engage mating parallel and horizontally spaced apart linear rows or arrays of teeth  138  formed on locking washers  104  which act as locking elements. The washer teeth  138  project inwardly toward the toothed racks  135  on the right and left lateral adjustment legs  136  of the cheek rest  32  which are disposed between the washers  104  and the clamping blocks  60  (see, e.g.  FIGS. 27 and 29 ). The toothed racks  135  formed on the cheek rest  32  are movable upwards and downwards along the vertical rows of teeth  138  on the washers (which remain fixed in vertical position) into a plurality of indexed positions formed by the meshed teeth. Washers  104  on each lateral side  42  of the butt pad assembly mounting extension  31  in one embodiment may have a generally U-shaped cross-sectional shape with two inwardly turned side flanges  104 - 3  on which the spaced apart vertical rows of teeth  138  are formed to lockably engage the cheek rest. The teeth  137  and  138  are mutually configured with an appropriate profile/contour that allows them to slideably move along each other as the cheek rest is adjusted when the cam lever  101  is in the release position. 
     In other embodiments contemplated, it bears noting than only one of the washers  104  may have teeth  138  and the other washer may be toothless. Accordingly, only one of the adjustment legs  136  of the cheek rest  32  will provide the desired indexing type adjustment of the cheek rest  32  and maintenance of the adjusted position which is an operable arrangement. However, use of two toothed washers  104  provides increased holding power for locking the cheek rest  32  in vertical position particularly in case the firearm is dropped and impacts a structure during carry or use. 
     In yet other possible embodiments, it bears noting that the toothed racks  135  on cheek rest  32  and teeth  138  on locking washers  104  on one or both may be omitted to rely on the clamping force produced by cam lever assembly  100  alone to retain the selected vertical position of the cheek rest via mutual frictional engagement between the slideable parts.  FIGS. 45 and 46  show this alternative embodiment.  FIG. 45  depicts a toothless locking washer  104 A and a toothless cheek rest  32 A is shown in  FIG. 46 . The toothless locking washer includes the two inwardly turned side flanges  104 - 3  previously described herein which act as locking elements that are slideably received in channels  135 - 1  of cheek rest  32 A to lock the cheek rest in vertical position when the cam lever assembly  100  is locked. Vertical adjustment of the cheek rest on chassis rear mounting extension  31  is the same as described elsewhere herein for the toothed embodiments. 
     Referring back now to the embodiment of  FIGS. 39-41 , cheek rest  32  is adjustable into a plurality of indexed vertical positions with respect to the rear mounting extension  31  of the chassis and firearm  20 . Cam lever  101  has a center release position and two opposing locking positions (e.g. up or down) as previously noted because the lever is oriented vertically. Lever  101  is pivotally movable upward or downwards between the two locking positions for cheek rest  32  height adjustment as well as to adjust the longitudinal position of the cheek rest and length of pull of the butt pad assembly  33 . 
     In operation, when the cam lever  101  is in the opened center release position (see, e.g.  FIG. 25 or 29 , the cheek rest  32  may be slid up or down in vertical position relative to the rear mounting extension  31  of the mid-stock  27  (chassis). The toothed racks  135  on each of the cheek rest right and left adjustment legs  136  engage and slip over the rows of teeth  138  on washers  104  (which remain stationary in vertical position with the cam lever  101  and related components). The biasing force imparted by the spring  107  of the cam lever assembly  100  against clamping blocks  60  force them laterally outwards to create a ratcheting action with accompanying audible “click” and a tactile sensation each time the cheek rest is incrementally raised or lowered in an indexed manner along the lightly meshing teeth. It bears noting that the same audible ratcheting action occurs when the cheek rest  32  (mounted to the clamping blocks  60 ) is slid forward and rearward on the mounting extension  31 , or when the adjustment rail  50  of the butt pad assembly  33  is slid forward or rearward. 
     When the desired cheek rest position is reached, the cam lever  101  is folded up or down against the cheek rest  32  into either of the two closed locking positions. This tightly meshes the cheek rest and locking washer mating teeth  137 ,  138  to lock the cheek rest in vertical position. 
     A method or process for adjusting the butt pad assembly and cheek rest of a firearm will now be briefly summarized. The triple-acting locking mechanism provides lockable longitudinal (horizontal) adjustability for both the butt pad assembly  33  and cheek rest  32 , and lockable vertical adjustability for the cheek rest. 
     In one embodiment, the method may comprise: providing a firearm stock including a longitudinally-extending chassis defining a mounting axis, a butt pad assembly slideably movable on the chassis in axial position, a vertically-adjustable cheek rest slideably movable on the chassis in axial position, and a triple-acting locking mechanism operably coupled to the butt pad assembly and cheek rest, wherein the locking mechanism is in a locked position locking the axial position of the butt pad assembly and cheek rest, and locking the cheek rest in a vertical position; changing the locking mechanism to an unlocked position which unlocks the butt pad assembly and cheek rest; sliding the butt pad assembly and cheek rest forward or rearward to desired axial positions of each; and changing the locking mechanism back to the locked position locking the butt pad assembly and cheek rest in the desired axial positions. The method may further comprise adjusting the vertical position of cheek rest when the locking mechanism is in the unlocked position, and changing the locking mechanism to the locked position to lock the vertical position of the cheek rest. In one embodiment, the locking mechanism may be a cam lever assembly having a cam lever movable between a release position and at least one locking position. In the same or other embodiments, the locking mechanism comprises a pair of clamping blocks laterally movable together and apart, the clamping blocks (1) lockingly engaging the chassis and butt pad assembly when the locking mechanism is in the locked position which locks the butt pad assembly and cheek rest in axial position, and (2) disengaging the chassis and butt pad assembly when the locking mechanism is in the unlocked position to allow adjustment of butt pad assembly and cheek rest in axial position. The cheek rest may be mounted to the clamping blocks which are slideable along the chassis to change the axial position of the cheek rest. 
     Numerous variations of the foregoing method and order of steps are possible depending on the needs and preferences of the user for adjusting the buttstock. 
     While the foregoing description and drawings represent exemplary embodiments of the present disclosure, it will be understood that various additions, modifications and substitutions may be made therein without departing from the spirit and scope and range of equivalents of the accompanying claims. In particular, it will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, sizes, and with other elements, materials, and components, without departing from the spirit or essential characteristics thereof. In addition, numerous variations in the methods/processes described herein may be made within the scope of the present disclosure. One skilled in the art will further appreciate that the embodiments may be used with many modifications of structure, arrangement, proportions, sizes, materials, and components and otherwise, used in the practice of the disclosure, which are particularly adapted to specific environments and operative requirements without departing from the principles described herein. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive. The appended claims should be construed broadly, to include other variants and embodiments of the disclosure, which may be made by those skilled in the art without departing from the scope and range of equivalents.