Patent Publication Number: US-2012036757-A1

Title: Gun-stock riser for AR15 type tactical firearm

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to shoulder fired firearms, particularly tactical firearms having gun-stock mechanisms that have adjustable length for efficiency of storage and handling and for adjustment of the firearms to suit the intended usage, needs and the anatomy of different users. More particularly, the present invention concerns the presence of cheek riser devices on gun-stocks to provide users with more efficient and secure aiming of the firearm. Even more specifically, the present invention is directed to a tactical gun-stock cheek riser mechanism that has a movable riser component to prevent riser interference with the charging handle movement of the adjustable length gun-stock of an AR15 type tactical firearm. 
     2. Description of the Prior Art 
     Tactical firearms have been use for a considerable period of time that incorporate gun-stock mechanisms that provide for adjustment of gun-stock length as desired between a minimum length and a maximum length. The shoulder engaging adjustable gun-stock mechanisms permit length adjustment to enable users of different anatomy to adjust the firearm to a length that is comfortable for that individual. The gun-stock mechanism can be adjusted to its minimum length when the rifle is to be used in close quarters, such as in the rooms of a building or in a wooded area where brush or trees might interfere with efficient use of the rifle. When tactical firearms are to be stored the user can adjust the length of the gun-stock to or near its minimum length so that the length of the rifle will facilitate efficient storage. This adjustable length feature also facilitates ease of transportation of tactical firearms in vehicles or in other modes of transportation. 
     AR15 type tactical rifles have a receiver structure within which a bolt member is movable rearwardly to eject the cartridge case of a spent or fired round of ammunition from the cartridge chamber of the rifle barrel and is movable forwardly by the energy of a bolt return spring to pick up another cartridge from a cartridge magazine of the rifle and propel it into the cartridge chamber of the rifle barrel. When no cartridge is present within the rifle barrel, the user of the rifle will manually engage or grasp a charging handle that is present at the rear portion of the rifle receiver and move it rearwardly. A bolt actuating shaft extends from the charging handle into the receiver and has connection with the bolt of the firing mechanism so that rearward movement of the charging handle also causes rearward movement of the bolt to its charging position and compresses the bolt return spring. When the charging handle is released the force of the bolt return spring will drive the bolt member forward, causing the bolt to pick up a cartridge from the cartridge magazine, propel the cartridge into the cartridge chamber of the rifle barrel and temporarily lock the bolt against rearward movement by the force of cartridge chamber pressure when the cartridge is fired. In the event something should interfere with complete rearward movement of the charging handle, the bolt will not be moved rearwardly sufficiently to adequately compress the bolt return spring. When this condition occurs and the charging handle is released it is likely that the forwardly moving bolt will have insufficient force to pick up a cartridge and feed it into the cartridge chamber and achieve locking actuation of the bolt. 
     It has been determined that the presence of cheek projections on the gun-stocks virtually all types of shoulder fired firearms often enable users to aim the firearm more accurately since the cheek projections, also known as “cheek risers” permit the user to comfortably rest the cheek of the user&#39;s face on the cheek riser and position the user&#39;s aiming eye in substantial alignment with the center of telescopes and other sighting and aiming devices that are mounted to the firearm. Cheek risers are especially advantageous when elevated sighting devices such as telescopes or laser sights are employed. These cheek risers may be defined by the structure of the gun-stock of the firearm or may be in the form of attachments that are mounted to the gun-stock. 
     In the case of tactical rifles of the AR15 type, the rifles typically have gun-stocks of adjustable length as mentioned above. When a cheek riser is present on an adjustable length gun-stock, depending on the adjusted position of the gun-stock, the cheek riser can interfere with manual rearward movement of the charging handle of the firearm to its cartridge charging position. This condition also causes the bolt to fail to reach its cartridge charging position and fails to completely load or compress the bolt return spring. Upon release of the charging handle the bolt return spring can fail to move the bolt forwardly with sufficient force to pick up a cartridge from the cartridge magazine and propel it into the cartridge chamber and can fail to completely lock the bolt in preparation for firing of the cartridge. This cartridge feeding malfunction often results in the cartridge being only partially stripped from the cartridge magazine or becoming misaligned in the receiver so that cartridge jamming occurs. The jammed cartridge must be cleared from the receiver and a new cartridge must be charged into the firing chamber of the barrel before the firearm can be fired. During tactical situations time is often of the essence and the user of the firearm could be subject to serious danger during the time sequence that is required for clearing a jammed cartridge and again charging the rifle from the cartridge magazine by manual operation of the charging handle. It is desirable, therefore to provide a cheek riser device or mechanism that also has a characteristic of movement that accommodates and does not interfere with the rearward movement of the charging handle of a rifle regardless of the condition of the adjustable length gun-stock. 
     SUMMARY OF THE INVENTION 
     It is a principal feature of the present invention to provide a novel cheek riser device for AR15 type tactical rifles which is easily movable during rearward movement of the charging handle of the firearm so that the cheek riser device does not impede rearward movement of the charging handle and thus permits normal spring urged forward bolt movement as a cartridge is charged into the cartridge chamber of the barrel of the firearm. 
     It is another feature of the present invention to provide a novel movable cheek riser for attachment to the gun-stock of a tactical rifle and having the capability for accommodating adjustment of the length of the gun-stock of the firearm and yet maintaining efficient cheek riser positioning at all adjusted lengths of the firearm gun-stock between its minimum length and its maximum length, without cheek riser interference with the cartridge charging operation of the firearm. 
     It is another feature of the present invention to provide a novel cheek riser mechanism having a first cheek riser part that is attached in fixed relation to the gun-stock of a shoulder fired firearm and having a second cheek riser part that has reciprocating movement relative to the first cheek riser part and is easily movable to prevent cheek riser interference with manually actuated cartridge charging. 
     It is an even further feature of the present invention to provide a gun-stock that incorporates a novel movable cheek riser mechanism wherein the gun-stock defines a guide and retention system having a cheek riser member movably mounted thereto and being movable in response to manually actuated movement of the charging handle of the firearm. 
     Briefly, the various objects and features of the present invention are realized through the provision of a cheek riser assembly that has a mounting base or saddle structure that is adapted for mounting to an adjustable gun-stock by means of mounting screws or other mounting devices. The mounting base or saddle is intended for substantially fixed relation with the gun-stock structure. The mounting base or saddle structure defines spaced forwardly extending cheek riser guide members that permit the upper curved portion of the gun-stock to b exposed and ensures that the charging handle of the firearm will not contact any portion of the mounting base or saddle structure during charging handle movement. The mounting base or saddle structure defines opposed elongate first guide members that are disposed in substantially parallel relation with one another. A cheek riser member is movably mounted to the mounting base or saddle structure by second guide members that are engaged with the first guide members. One or more riser springs continuously urge the cheek riser member forwardly to a use position against the force of the riser springs. The force of the riser springs is overcome by manually applied rearward movement of the charging handle of the firearm, this preventing interference of the riser member with the rearward movement of the charging handle and ensuring complete spring urged forward cartridge charging movement of the bolt of the firearm for efficiency of cartridge charging and minimizing cartridge jamming during manually actuated charging of a cartridge from the cartridge magazine into the firing chamber of the firearm barrel. Movement of the cheek riser member may be linear movement or any other character of movement that permits movement of the cheek riser member in response to charging handle movement of the firearm. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the preferred embodiment thereof which is illustrated in the appended drawings, which drawings are incorporated as a part hereof. 
       It is to be noted however, that the appended drawings illustrate only a typical embodiment of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
       IN THE DRAWINGS 
         FIG. 1  is a side elevation view showing a rear portion of a tactical firearm having a gun-stock of adjustable length and having a movable cheek riser mechanism embodying the principles of the present invention being in assembly with the gun-stock and further showing the charging handle of the firearm mechanism being pulled rearwardly during a manually actuated charging stroke by with the hand of a user and being in contact a movable slide member of the movable cheek riser mechanism; 
         FIG. 2  is an elevation view similar to  FIG. 1 , showing the movable cheek riser slide member being further moved rearwardly as the rearward charging movement of the charging handle continues; 
         FIG. 3  is an elevation view similar to  FIGS. 1 and 2 , showing the position of the movable cheek riser slide member when the charging handle of the firearm has been moved to the full extent of its rearward movement during manually actuated cartridge charging of the firearm mechanism; 
         FIG. 4  is an isometric illustration showing the cheek riser mechanism of the present invention with the movable cheek riser slide member being shown at its forward most or normal position; 
         FIG. 5  is a bottom view of the movable cheek riser mechanism of  FIG. 4 ; 
         FIG. 6  is an isometric illustration showing the bottom and side details of the movable cheek riser mechanism of  FIGS. 4 and 5 ; 
         FIG. 7  is a front view of the cheek riser mechanism of  FIGS. 4-6 ; 
         FIG. 8  is a rear view of the movable cheek riser mechanism of  FIGS. 4-6 ; 
         FIG. 9  is a plan view of the riser base or saddle structure of the cheek riser mechanism of the present invention being shown mounted in substantially fixed relation to a gun-stock and showing a pair of spaced guide members for guiding engagement within guide slots of a movable cheek riser slide member and slide stop members for guiding and limiting reciprocating movement of the cheek riser slide member; and 
         FIG. 10  is a bottom view of the cheek riser slide member of the movable cheek riser mechanism of the present invention, showing internal parallel guide grooves for slide control and for limiting cheek riser slide movement. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     Referring now to the drawings and first to  FIG. 1 , the rear portion of a shoulder fired AR15 type rifle is shown generally at  10  and has a receiver  12  from which projects a handgrip  14 . A cartridge charging handle  15  of the rifle receiver is shown being moved from its retracted position by the fingers of a user&#39;s hand engaging the charging handle  15  and applying a pulling force. This pulling force moves the charging handle  15  and the bolt mechanism within the receiver rearwardly against the resistance of a bolt return spring that is located within the buffer tube of the firearm. In the charging handle position shown in  FIG. 1  it should be noted that the rear portion of the charging handle is in contact with a cheek riser slide member which is discussed in greater detail below. 
     The charging handle  15  is mounted to a charging shaft  17  that extends into the receiver  12  and is connected with a bolt mechanism that is movable within the receiver of the firearm during cartridge charging and cartridge firing sequences. The charging handle  15  is manually movable rearwardly against the force of a bolt return spring and moves the bolt mechanism of the firearm rearwardly in preparation for charging the cartridge chamber of the firearm barrel with a cartridge. When the manual force on the charging handle  15  is released the bolt and the charging handle are propelled forwardly by the force of the bolt return spring. During this spring urged forward movement of the bolt mechanism, the bolt will pick up a cartridge from the cartridge magazine of the firearm and move it forwardly into the cartridge chamber of the barrel. The bolt mechanism will be locked at its fully forward or closed position, thereby securing and sealing a cartridge within the cartridge chamber and causing the bolt mechanism to remain closed and to resist rearward movement by the gas pressure that is developed upon firing of the cartridge within the cartridge chamber. The bolt mechanism is unlocked and moved rearwardly toward its full open position by cartridge gas pressure when the bullet being propelled through the rifle barrel passes a gas port and exposes the gas port to cartridge gas pressure. Cartridge gas pressure from the gas port of the firearm barrel acts on a piston rod member causing the piston rod to be moved rearwardly and apply a bolt unlocking force to the bolt mechanism. The piston rod force also moves the bolt mechanism rearwardly to eject the spent cartridge and repeat the cartridge charging process. 
     In the similar elevation view of  FIG. 2  the charging operational sequence is shown in further progress, with the cartridge charging handle  15  of the rifle receiver having been pulled further rearwardly by the fingers of the user&#39;s hand, such that the cheek riser slide member is also being moved further rearwardly by the manual force being applied to the charging handle. A slide return spring of the cheek riser slide mechanism is being loaded during this rearward slide movement so that when the manual force on the charging handle is released the cheek riser slide member will be moved forwardly by the force of a slide return spring toward its original position. 
     The elevation view of  FIG. 3  illustrates a further portion of the manually actuated operational sequence for charging a cartridge into the cartridge chamber of the firearm barrel. The Figure shows the charging handle  15  of the firearm being manually pulled substantially to its rearmost position and ready to be released for spring urged forward movement by the bolt return spring. The Figure also shows the cheek riser slide member having been moved by the charging handle substantially to its rearmost position. When the charging handle is released from the pulling force the bolt return spring will move the charging handle forwardly to its retracted position as the bolt return spring moves the bolt through the cartridge charging portion of its cartridge charging cycle. As the charging handle is moved forwardly the slide return spring of the cheek riser mechanism will move the cheek riser slide member forwardly to its operational position. This feature permits the firearm to be provided with a cheek riser to facilitate efficiency of firearm aiming and also ensures that the cheek riser is movable during manually actuated cartridge charging cycling and does not interfere with the cartridge charging cycle of the firearm. During a firing sequence the lost-motion connection of the charging handle with the bolt mechanism ensures that the charging handle remains at its forward most or retracted position. 
     The receiver  12  of the firearm  10  defines a gun-stock mount  16  that receives the externally threaded end  18  of a tubular gun-stock support member  20  that is also referred to as a buffer tube. Typically the buffer tube contains a bolt return spring and a spring follower, with the bolt return spring urging the spring follower in the forward direction toward the barrel of the firearm. When a cartridge is fired a cartridge gas energized bolt actuating rod member is moved rearwardly by cartridge gas pressure to unlock the bolt member and move it rearwardly against the resistance of the bolt return spring. This bolt recoil movement causes the bolt mechanism to move the spring follower rearwardly and accomplishes loading of the bolt return spring of the buffer tube. When rearward movement of the bolt mechanism has been overcome by the resistance of the bolt return compression spring the spring will drive the bolt mechanism forwardly to pick up a cartridge from a cartridge magazine of the receiver  12  and move the cartridge into the cartridge chamber of the firearm barrel. A lock plate  22  and lock nut  24  secure the buffer tube member  20  to the receiver  12  and permit the gun-stock to be easily removed from the receiver  12  and replaced if desired. 
     A moveable gun-stock  26 , for engagement with the shoulder of a user, defines an internal receptacle within which is adjustably received the rear end portion of the tubular gun-stock member or buffer tube  20 . The buffer tube  20  further defines an internal guide slot within which is received an elongate guide portion of the tubular gun-stock member  20 , thus preventing rotation of the gun-stock relative to the buffer tube and permitting forward and rearward adjustment of the gun-stock member  26  relative to the buffer tube  20  to lengthen or shorten the firearm as suits the needs and desires of the user. Obviously, when the gun-stock member  26  is adjusted to its maximum length, a cheek riser member, if present on the gun-stock, will typically be located beyond the rearward stroke of the charging handle and will not interfere with the charging cycle of the firearm. However, if a cheek riser is present on the gun-stock then its presence could prevent the gun-stock from being adjusted to its minimum or intermediate length. Thus the presence of a cheek riser on a gun-stock could constitute a distinct disadvantage concerning normal use of the firearm. 
     A pivotally mounted latch member  32  is manually positioned to a latched position to secure the gun-stock member  26  at any desired position along the length of the tubular gun-stock member  20  between minimum and maximum length positions. A pivotally mounted latch release member  34  is mounted to the moveable gun-stock member  26  and upon manual movement about its pivot  36  causes latch releasing movement of a latch release pin  38  which in turn causes latch releasing movement of the latch member  32 . This latch releasing movement frees the gun-stock member  26  for linear gun-stock position adjusting movement along the length of the tubular gun-stock member  20 . 
     As mentioned above, it is often desirable to include a cheek riser on the gun-stock of a firearm to aid the user in positioning the user&#39;s eye for efficient aiming, especially if the firearm is fitted with an elevated sighting device such as a telescope. The movable cheek riser mechanism of the present invention can be provided in the form of an assembly that is mounted to a standard gun-stock or may be provided as a component or structure of a gun-stock. If a conventional cheek riser is present on the gun-stock of an AR15 type firearm the riser will typically interfere with manual rearward movement of the charging handle  15 , especially if the gun-stock has been adjusted to its more collapsed position for minimum stock length as shown in  FIG. 1 . This interference can prevent the bolt of the firearm from being moved rearwardly to its full extent for maximum compression of the bolt return spring and thus can prevent the bolt from being cycled forwardly with sufficient spring induced force to pick up a cartridge from the cartridge magazine and charge the cartridge into the firing chamber of the firearm barrel. It is desirable, therefore, to provide an AR15 type firearm with a gun-stock having cheek riser assembly that incorporates a movable cheek riser member that is easily movable during charging handle manipulation so that the charging handle can be cycled to its full extent and the movable cheek riser will not interfere with the cartridge charging operation. This feature also permits the movable cheek riser to be returned to its cheek supporting position by spring force when the charging handle has been released by the firearm user and has been moved forwardly by the bolt return spring. 
     Referring now to  FIGS. 1-6 ,  9  and  10  a cheek riser assembly having a variable position capability is shown generally at  40  and comprises a riser saddle structure  42  having a rear portion of generally U-shaped cross sectional configuration that defines a downwardly facing recess  43  that substantially fits the curvature of the upper curved surface portion  44  of the gun-stock  26 . The riser base or saddle structure  42  is preferably composed of any of a wide range of polymer materials but may be composed of a metal such as steel, aluminum alloy or magnesium if desired. A pair of spaced cheek riser guide members  46  and  48  are integral with the riser base or saddle structure  42  and project forwardly from the U-shaped portion of the base or saddle structure  42 . The spaced cheek riser guide members  46  and  48  each define externally projecting elongate guide rail members  50  and  52 . The spacing of the cheek riser guide members  46  and  48  permits the curved upper portion  44  of the gun-stock  26  to be exposed so that the charging handle  15  of the firearm will not come into contact with any portion of the riser saddle structure  42  during its reciprocating charging movement. Thus it is possible for the charging handle  15  to actually come into contact with the upper curved surface  44  of the gun-stock without contacting any portion of the U-shaped saddle structure  42 . The U-shaped portion of the saddle structure  42  also defines a pair of spaced guide and stop projections  54  and  56 , shown in  FIG. 9  that are disposed in generally parallel relation with one another and project upwardly and laterally from the U-shaped saddle structure. A plurality of saddle mounting tabs  58 ,  60 ,  62  and  64  extend downwardly from opposed edge portions  66  and  68  of the riser saddle structure  42  and each define mounting holes  70  that receive mounting screws  72  or any other suitable retainer devices that extend into the structural material of the movable gun-stock member  26 . 
     As shown in  FIGS. 9 and 10  a movable cheek riser member or slide  74  is received for linear reciprocating movement by the riser saddle structure  42  and defines spaced elongate internal guide slots  76  and  78  that receive the spaced guide and stop projections  54  and  56  of the U-shaped saddle structure. The internal guide slots  76  and  78  have closed ends that terminate short of the respective ends of the movable cheek riser member as shown in  FIG. 10 . The closed ends of the internal guide slots define stops that can be contacted by the respective ends of the spaced stop projections  54  and  56  to limit the length of the reciprocating movement of the movable riser member. Interrelation of the spaced stop projections  54  and  56  and the internal guide slots  76  and  78  also permit the normal position of the forward end of the movable cheek riser slide member to be substantially even with the forward end of the gun-stock  26  as is essentially shown in  FIG. 1 . These guide features permit the cheek riser member  74  to be linearly movable relative to the cheek riser saddle structure  42 , the length of linear movement being greater than the manually energized rearward linear extension movement of the charging handle  15  of an AR15 type tactical firearm or its military equivalent. 
     As shown in  FIGS. 5 and 6 , the rearward end portion of the movable cheek riser member  74  can incorporate internal generally U-shaped structural ribs  76 ,  78 ,  80  and  82  that enhance the structural integrity of the cheek riser saddle structure  42 . These U-shaped internal structural ribs establish contact with the upper curved surface  44  of the movable gun-stock  26  when the saddle structure  42  of the cheek riser assembly  40  is mounted in fixed relation with the movable gun-stock  26 . 
     As shown in  FIG. 5  and  FIG. 10 , the cheek riser saddle structure  42  also defines an elongate structural section  84  of generally cylindrical configuration which is also integral with the cheek riser saddle structure  42 . This elongate cylindrical structural section defines a through passage  86  within which extends a plunger member  88  and a plunger spring  90  that is preferably in the form of a helical compression spring. A plunger support plate member  92  to which the plunger member  88  is fixed is mounted within a recess  94  that is defined within a front end wall  96  of the cheek riser slide member  74  by mounting screws  97  or other suitable fastener devices that extend through fastener openings  98  and are threaded into or otherwise engage within openings of the plunger support plate  92 . If desired the support plate structure at the fastener openings may be internally threaded to receive the threads of the mounting screws  97 . Also if desired the support plate may be mounted to the front end wall  96  by means of screw, nut and lock washer assemblies or by any other suitable means for attachment or mounting. 
     The front end wall  96  of the movable cheek riser member or slide  74  defines guide slots or notches  100  and  102  within which the externally projecting elongate guide members  50  and  52  are movably received. As the movable cheek riser or slide member  74  is moved linearly in the rearward direction by the charging handle of the firearm or by manual force applied by the user of the firearm the front end portion of the movable cheek riser or slide member will be guided and will be prevented from separating from the fixed cheek riser saddle structure  42 . 
     As the riser slide member  74  is moved rearwardly by the charging handle  15  of the firearm or by manually applied force the plunger member  88 , being mounted to the forward wall structure  96  of the riser slide member, will be moved within the through passage  86  of the elongate structural section  84  of the riser base or saddle structure  42 . As this occurs the compression spring  90  will be further compressed so that a return spring force exists that urges the riser slide member toward its original operational position. Thus, during normal charging operations for the firearm the charging handle is pulled to its maximum extent and released. As the charging handle is pulled it engages and causes movement of the riser slide member  74  so that the riser slide member does not interfere with complete and efficient charging handle movement. When the charging handle is released by the firearm user the bolt return spring will move the charging handle forwardly to its original position, in the process causing charging of a cartridge into the cartridge chamber of the firearm. During forward movement of the charging handle the spring force on the riser slide member will move the riser slide member forwardly, essentially following the charging handle. When the charging handle  15  has become seated the riser slide member will have become located at its operational position, ready for contact of the user&#39;s cheek with the riser slide member. 
     In view of the foregoing it is evident that the present invention is one well adapted to attain all of the objects and features hereinabove set forth, together with other objects and features which are inherent in the apparatus disclosed herein. 
     As will be readily apparent to those skilled in the art, the present invention may easily be produced in other specific forms without departing from its spirit or essential characteristics. The present embodiment is, therefore, to be considered as merely illustrative and not restrictive, the scope of the invention being indicated by the claims rather than the foregoing description, and all changes which come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein.