Patent Publication Number: US-2020278171-A1

Title: Removable stock adapter

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/795,516, filed Jan. 22, 2019, incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     Embodiments relate generally to a firearm capable of accepting a removable stock and more particularly to a device for securely and removably attaching a removable stock to a firearm. 
     BACKGROUND 
     A stock may be provided on a firearm to support the firearm against a person&#39;s shoulder while the firearm is being aimed and fired. The stock may improve firing accuracy and may absorb and distribute recoil forces to reduce discomfort. The stock may be configured to be removed from other parts of the firearm, for example to prepare the firearm for safe storage and/or transport, and for re-attachment to prepare the firearm for use. 
     A removable stock may include a connector that couples securely to a corresponding stock connector on a firearm. For example, a channel, ridge, or flange on the stock may firmly engage with a corresponding channel, ridge, or flange on the firearm. A picatinney rail connector on a stock may engage with a corresponding picatinney rail on a firearm. Some firearms may use a stock fitted with a buffer tube having a threaded end configured to engage with a corresponding threaded aperture on the firearm. Some buffer tubes have an adapter for connecting to a picatinney rail on a firearm. 
     The firearm may include a securing mechanism configured to retain a removable stock firmly to the firearm. An example of a securing mechanism includes a spring-loaded pushbutton positioned at the back end of the receiver on the firearm such that the pushbutton may extend into a corresponding pushbutton aperture on the stock. When engaged with one another, the pushbutton and pushbutton aperture oppose separation of the stock from the firearm. The pushbutton may be positioned to avoid unintended release of the stock from the firearm and may therefore be difficult to reach and/or operate. Deliberately operating the securing mechanism to intentionally remove the stock from the firearm may be difficult for a person wearing gloves or a person with poor finger dexterity. The connector to the firearm on the stock and the connector to the stock on the firearm may be engaged so tightly as a result of friction or mechanical interference that striking the stock with a mallet or similar tool may be helpful to separate the stock from the firearm. A prying tool may be needed to access and/or provide sufficient leverage to operate the securing mechanism holding the stock to the firearm. Carrying a suitable tool for removing the stock may not be convenient. Striking a firearm or using a prying tool to remove a stock presents risks of cosmetic and mechanical damage to the stock and other parts of the firearm and injury to the person using the tool, and may cause unintended discharge of the firearm if a person fails to unload the firearm before attempting to remove the stock. 
     SUMMARY 
     An example apparatus embodiment of a stock adapter includes an adapter housing; a firearm connector on a first side of the adapter housing; a stock connector on a second side of the adapter housing opposite the first side; and a stock release actuator including an actuator lever rotatably coupled to the adapter housing, with the actuator lever positioned to contact a stock release pushbutton on a firearm when the firearm connector on the stock adapter is attached to a connector for a removable stock on a firearm. The adapter housing is preferably formed with an aperture configured to receive the stock release pushbutton. 
     The actuator lever extends out from a bottom side of the adapter housing. The stock release actuator is configured to depress the stock release pushbutton on the firearm by a displacement of an outer end of the actuator lever toward the first side of the adapter housing, i.e., toward the firearm and in a direction opposite to the direction for pulling the trigger to discharge the firearm. The actuator lever is formed with a shoulder extending outward from a front side of the actuator lever. The shoulder is positioned on the actuator lever to contact and depress the stock release pushbutton. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a side view of an example embodiment of a stock adapter configured for coupling to a removable stock having a buffer tube. 
         FIG. 2  shows a view toward a front end of an example stock adapter, illustrating an example of a stock release actuator configured for use with all disclosed stock adapter examples. 
         FIG. 3  shows a view toward a back end of the example stock adapter of  FIGS. 1 and 2 , illustrating an example of a stock connector configured for receiving a buffer tube on a stock. 
         FIG. 4  shows a side view of an example of an actuator lever included in the stock release actuator of the disclosed stock adapter embodiments. 
         FIG. 5  shows an exploded pictorial view of an example stock adapter, further illustrating examples of components included in the stock release actuator of  FIG. 2 . 
         FIG. 6  shows a side view of the example stock adapter positioned for connection to an example of a removable stock fitted with a buffer tube having a threaded end. 
         FIG. 7  is a side view continuing the example of  FIG. 6 , showing the example stock adapter connected to the removable stock. 
         FIG. 8  is a side view of an example stock adapter having the stock release actuator shown in  FIGS. 1, 2, 4, 5, 6, and 7 , and further illustrating an example of a stock adapter having a stock connector matching a stock connector on a firearm. 
         FIG. 9  is a side view of an example stock connector embodiment interposed between an example stock and an example firearm, with the stock and firearm drawn in broken lines to indicate that the stock and firearm are not part of the disclosed embodiments of a stock adapter. 
         FIG. 10  is a side view continuing the example of  FIG. 9 , showing an example of the stock adapter separated from the example firearm and from the example stock, and further illustrating examples of a stock connector on the firearm, a connector to a firearm on the stock, an example stock connector on the stock adapter, and an example firearm connector on the stock adapter. 
     
    
    
     DESCRIPTION 
     Apparatus embodiments include a stock adapter configured for safe and easy removal and re-attachment of a stock from other parts of a firearm, without the use of tools and without alteration of the stock and firearm. The example stock adapter embodiments oppose accidental separation of the stock from the firearm and simplify intentional separation of the stock from the firearm. The example stock adapter embodiments securely and removably attach to a firearm between a firearm connector on the stock and a corresponding stock connector on the firearm. Depending on the configuration of the firearm, the stock connector on the firearm may be at the back end of the receiver or may be some distance from the receiver, where the receiver includes the firing mechanism of the firearm. A connector on a front end of the stock adapter has a shape and function corresponding to the connector on the front end of a removable stock configured for attachment to a firearm. Another connector on the back end of the stock adapter has a shape and function corresponding to the stock connector on the firearm. When not in use or when needed for use on another firearm, the stock adapter may be easily removed from the stock and firearm and the stock may be reattached directly to the firearm without the intervening stock adapter. 
     A stock release actuator included with the stock adapter is positioned to easily and safely depress a stock release pushbutton on the firearm. The stock release actuator provides an actuator lever with mechanical advantage to increase finger force against the lever to a magnitude and direction sufficient for fast and easy depression of the stock release pushbutton. The stock release actuator eliminates the need for a prying tool such as a screwdriver or knife blade to depress the stock release pushbutton. Stock adapter embodiments are advantageous for a person wearing gloves or a person with insufficient finger strength or dexterity to quickly and safely separate the stock from the firearm without the use of tools. 
     Turning to the examples of  FIGS. 1-10 , an adapter housing  102  having a front side  108  and a back side  110  is included with all disclosed embodiments of a stock adapter  100 . The front side  108  of the adapter housing  102  includes a connector  170  configured for removable attachment to a corresponding connector on a firearm. The connector  170 , also referred to herein as the firearm connector  170 , preferably matches the size, shape, and attachment features of a corresponding connector on the front end of a removable stock configured for connection to the firearm. The back side  110  of the adapter housing  102  includes another connector  172  configured for removable attachment to a corresponding connector on a stock. The connector  172  on the back side of the adapter housing, also referred to herein as the stock connector  172 , optionally matches the size, shape, and attachment features of a corresponding connector on a firearm configured for connection of a removable stock. Alternatively, the stock adapter  100  may include a stock connector that differs from the stock connector on a firearm, thereby enabling sticks with different kinds of connectors to be attached to a firearm. Examples of the firearm connector  170  and stock connector  172  include, but are not limited to, two or more rails on a connector configured for engagement with two or more rails and/or channels on the opposing connector, a buffer tube, a hollow cylindrical receiver for a buffer tube, a picatinney rail, and a picatinney rail adapter and/or picatinney rail connector. 
     A stock release actuator  168 , preferably included in all embodiments of the stock adapter  100 , includes an actuator lever  134  rotatably coupled to the adapter housing  102 . The actuator lever  134  is positioned in the adapter housing to contact a stock release button on a firearm when the firearm connector  170  on the stock adapter  100  is connected to the corresponding stock connector on the firearm. An amount of force applied to the actuator lever by a person&#39;s finger is increased through the mechanical advantage of the stock release actuator and directed onto the spring-loaded stock release button on the firearm to depress the button, enabling the stock adapter  100 , and a stock when attached to the stock adapter, to be released from the firearm and/or connected to the firearm without the use of a separate tool for depressing the stock release pushbutton. 
     The stock release actuator  168  is preferably configured so that the actuator lever  134  is unlikely to be mistaken for the trigger for discharging the firearm. The actuator lever  134  may be held in a rest position by the spring-loaded stock release pushbutton urging the actuator lever toward the back side  110  of the stock adapter  100 . Operating the stock release actuator  168  to decouple the stock adapter  100  from the firearm requires a displacement of the outer end  178  of the actuator lever  134  in a forward direction  128 , toward the receiver of the firearm and in a direction opposite to the direction in which the trigger is pulled to discharge the firearm. 
     Embodiments of the stock adapter  100  are further configured to provide an adjustable retaining force for holding the firearm connector  170  on the front side  108  of the adapter housing  102  to the corresponding connector on the back of the firearm. A grub screw  164  threadably engaged with the adapter housing may be selectively extended and retracted to press against the firearm&#39;s receiver, thereby increasing or decreasing an amount of force pressing the firearm connector  170  on the stock adapter  100  against the corresponding stock connector on the firearm. The grub screw  164  may be set for easy separation of the stock adapter  100  from the firearm after activation of the stock release actuator  168 , for engagement between the stock adapter and firearm that is sufficiently strong to prevent separation of the parts without substantial effort, or for intermediate degrees of difficulty in separating the stock adapter from the firearm as selected by the person making the adjustment. 
     The example of a stock adapter in  FIG. 1  includes the firearm connector  170  on the front side  108  of the adapter housing  102 , the stock connector  172  on the back side  110  of the adapter housing, the actuator lever  134  extending outward from a bottom side  112  of the adapter housing, and a grub screw  164  threadably engaged with the adapter housing. The actuator lever  134  is part of the stock release actuator  168 . When extended outward, the grub screw is positioned to press against the receiver of the firearm to which the stock adapter  100  is attached. In the example of  FIG. 1 , the stock connector  172  is configured as a threaded aperture  162  for receiving a buffer tube on a stock. 
       FIG. 2  shows an example of the stock release actuator  168  in a view toward the front side  108  of the stock adapter  100 . In the example of  FIG. 2 , the firearm connector  170  includes a pair of opposing rails and optional channels configured to attach to a corresponding stock connector on a firearm, a right-side rail  154 , a right-side channel  156 , a left-side rail  158 , and a left-side channel  160 . The actuator lever  134  fits into a lever slot  152  formed in the adapter housing. A retaining plate  146  attached to the adapter housing with fasteners  148  holds the actuator lever  134  in the lever slot  152 . 
     When the stock adapter  100  is attached to a firearm, the stock release pushbutton on the firearm extends into a release button aperture  166 , preferably engaging the walls of the aperture  166  with a sliding fit and opposing separation of the firearm connector  170  from the corresponding stock connector on the firearm. Displacing the outer end  178  of the actuator lever  134  in a forward direction  128  (ref.  FIG. 1 ) compresses the spring-loaded stock release pushbutton on the firearm, disengaging the pushbutton from the release button aperture  166  and enabling separation of the firearm connector  170  on the stock adapter  100  from the corresponding stock connector on the firearm. The outer end  178  of the actuator lever projects outward from the bottom side  112  of the adapter housing  102  to enable the lever to be displaced by pressure from a person&#39;s finger. When finger pressure is removed from the actuator lever  134 , the actuator lever may be moved to its rest position toward the back end of the lever slot  152  by force exerted on the actuator lever by the stock release pushbutton. 
     An example of the back side  110  of the stock adapter  100  is shown in  FIG. 3 . In  FIG. 3 , the example stock connector  172  is configured as a receiver for a buffer tube. The stock connector  172  may optionally be formed as a hollow cylinder sized for a sliding fit of a buffer tube, or alternatively for threadable engagement with a buffer tube as suggested by a threaded aperture  162  formed in the stock connector. As suggested in the example of  FIG. 3 , the grub screw  164  may be accessible from the back side  110  of the adapter housing to permit adjustment of the screw&#39;s extension from the front side  108  of the stock adapter  100 . 
       FIG. 4  shows some details of an example actuator lever  134  included in the stock release actuator  168  of the stock adapter  100 . A pivot pin  136  passes through the center of rotation  180  of the actuator lever  134 . Optional bushings  138  may be placed on the pivot pin  136  on both sides of the actuator lever. The bushings  138  and pivot pin fit into a bushing slot  140  formed in the adapter housing (ref  FIG. 5 ) to enable easy rotation of the actuator lever relative to the adapter housing. A rounded shoulder  142  projecting from a front side of the actuator lever  134  is positioned to depress the stock release pushbutton on a firearm when the stock adapter is connected to the firearm. The amount of mechanical advantage developed by the stock release actuator  168  may be estimated as the ratio of a first value corresponding to the separation distance R 1  from the center of rotation  180  to the contact point of a finger against the actuator lever, to a second value corresponding to the separation distance R 2  from the center of rotation  180  to the shoulder  142 . For the example embodiments of a stock adapter  100  disclosed herein, R 1 /R 2 &gt;1, i.e., the mechanical advantage of the stock release actuator is greater than one and the compression force applied to the stock release pushbutton is greater than the compression force applied by a finger to the actuator lever. 
       FIG. 5  shows some additional features of an example stock adapter  100  in an exploded pictorial view. The firearm connector  170  is positioned on the front side  108  of the adapter housing to engage with a corresponding stock connector on the firearm. The firearm connector  170  may optionally include a right-side channel  156  formed near the right side of the adapter housing  102  and a left-side channel  160  formed near the left side of the adapter housing. The stock connector  172  on the back side  110  of the adapter housing is positioned to engage with a corresponding connector on a stock. The adapter housing  102  is formed with slots and/or apertures for the stock release actuator  168 , including the lever slot  152 , stock release button aperture  166 , bushing slots  140 , and threaded apertures  150 . The actuator lever  134 , stock release pushbutton on the firearm, bushings  138 , pivot pin  136 , grub screw  164 , and fasteners  148  for the retaining plate  146  fit into their corresponding apertures. The component parts of the stock release actuator  168 , including the actuator lever  134 , the pivot pin  136 , and one or more bushings  138  are retained to the adapter housing  102  by the retaining plate  146 . Another threaded aperture  150  formed in the adapter housing accepts the grub screw  164 . 
       FIGS. 6 and 7  show examples of a removable stock  202  with a threaded buffer tube  210  and examples of the stock adapter  100 . In the example  250  of  FIG. 6 , the stock adapter  100  is in an example of a position for connection of the stock connector  172  to the threaded end  220  of a buffer tube  210  on a removable stock  202  having a buttstock  222  attached to the buffer tube. An optional locking ring  218  may be threaded onto the threaded portion  220  of the buffer tube  210 . In the example of  FIG. 7 , the threaded end of the buffer tube has been assembled to the threaded aperture  162  on the back side  110  of the stock adapter  100 . A locking ring  218  optionally threaded onto the buffer tub may be tightened against the stock adapter  100  to retain the stock very securely in the stock adapter. Even when the stock is very firmly attached to the stock adapter, the stock adapter  100  may be easily attached to and removed from the firearm by operation of the stock release actuator  168  on the stock adapter, for example by displacing the actuator level  134  in the direction marked by an arrow  144  to depress the stock release pushbutton sufficiently to unlock the stock adapter from the firearm. The arrow  144  represents a displacement of the outer end  178  of the actuator lever  134  in a forward direction  128 , away from the back side  110  of the adapter housing  102 . 
       FIG. 8 . shows an example of a stock adapter having a firearm connector  170  incorporating rails and/or channels, possibly configured for attachment to a picatinney rail, and a stock connector  170  also incorporating rails and/or channels, possibly configured for attachment to a picatinney rail. 
       FIG. 9  shows an example of a stock adapter  100  attached to an example of a stock  222  and an example of a firearm  200 .  FIG. 10  continues the example of  FIG. 9 , showing an example  300  of the firearm  200  disconnected from the stock adapter  100  by a vertical displacement  176  of the stock adapter relative to the firearm, and further showing the example stock  222  disconnected from the stock adapter  100  by a longitudinal displacement  174  of the stock from the stock adapter. The example firearm  200  includes an example of a stock connector  212  configured for connection to a removable stock  202 . The firearm connector  170  on the stock adapter  100  is preferably configured to connect to the stock connector  212  on the firearm  200 . The stock connector  212  may include one or more rails  204  for engaging with a corresponding connector on a stock.  FIG. 10  further illustrates an example of a stock release pushbutton  206  which may be used to retain the stock adapter  100  and/or the stock  222  to the firearm.  FIG. 10  also represents an example of a stock having a firearm connector  214  including one or more channels and/or rails  208  for coupling the stock to a firearm. The stock connector  172  on the stock adapter  100  is preferably configured to connect to the firearm connector  214  on the removable stock  222 . 
     Unless expressly stated otherwise herein, ordinary terms have their corresponding ordinary meanings within the respective contexts of their presentations, and ordinary terms of art have their corresponding regular meanings.