Patent Publication Number: US-9410763-B2

Title: Angle-adjustable buffer tube system

Description:
The current application claims a priority to the U.S. Provisional Patent application Ser. No. number 62/039,243 filed on Aug. 19, 2014. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to a buffer tube system for mounting a stock to a firearm. More specifically, the present invention is an angle-adjustable buffer tube system that allows the firearm to be rotated during use of an offset iron sight without the shooter losing cheek weld with the stock. 
     BACKGROUND OF THE INVENTION 
     When engaging targets at long range, it is most common for a shooter to utilize a scope or similar sight that has been properly calibrated to accommodate for the multiple ballistic factors that may affect the flight trajectory of a projectile after being discharged. However, in the event that the shooter is required to engage targets at a closer range, a long range scope or sight may prove disadvantageous due to the magnification provided by the scope or sight. Because of the possible need for a shooter to rapidly engage targets at both close range and long range, it is common to mount an offset iron sight to the firearm as well. The offset iron sight is utilized as a close range backup sight to the primary scope or similar sight that is utilized for long range shooting. 
     While an offset iron sight functions in the exact same manner as a conventional iron sight, the shooter is disadvantaged due to the fact that the firearm that he or she is holding must be moved and held in an unfamiliar manner. An offset iron sight is typically offset at a 45° angle from the horizontal plane in order to avoid impeding the use of a primary scope or sight when the offset iron sight is mounted to a firearm. This can create an awkward and uncomfortable shooting experience for the shooter due to the fact that the entire firearm must be tilted, shifting the stock from a stable position on the shooter&#39;s shoulder. As a result, the shooter is much less likely to be successful when shooting the firearm from this position. 
     The present invention is an angle-adjustable buffer tube system that allows a shooter to rotate a firearm when utilizing an offset iron sight without shifting or otherwise manipulating the stock from a stable position against the shooter&#39;s shoulder. This allows the shooter to maintain cheek weld with the stock and keep his or her eyes on a target when transitioning from a primary scope or sight to the offset iron sight and vice versa. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top exploded perspective view of the present invention. 
         FIG. 2  is a bottom exploded perspective view of the present invention. 
         FIG. 3  is an exploded side view of the present invention. 
         FIG. 4  is a top perspective view of the present invention in the neutral configuration. 
         FIG. 5  is a bottom perspective view of the present invention in the neutral configuration. 
         FIG. 6  is a side view of the present invention in the neutral configuration. 
         FIG. 7  is a cross-sectional view of the present invention in the neutral configuration taken along line A-A of  FIG. 6 . 
         FIG. 8  is a rear internal view of the present invention in the neutral configuration. 
         FIG. 9  is a top perspective view of the present invention in the right-handed tilted configuration. 
         FIG. 10  is a side view of the present invention in the right-handed tilted configuration. 
         FIG. 11  is a cross-sectional view of the present invention in the right-handed tilted configuration taken along line B-B of  FIG. 10 . 
         FIG. 12  is a rear internal view of the present invention in the right-handed tilted configuration. 
         FIG. 13  is a top perspective view of the present invention in the left-handed tilted configuration. 
         FIG. 14  is a bottom perspective view of the present invention in the left-handed tilted configuration. 
         FIG. 15  is a side view of the present invention in the left-handed tilted configuration. 
         FIG. 16  is a cross-sectional view of the present invention in the left-handed tilted configuration taken along line C-C of  FIG. 15 . 
         FIG. 17  is a rear internal view of the present invention in the left-handed tilted configuration. 
         FIG. 18  is a top exploded perspective view of the buffer tube and the firearm-mounting tube. 
         FIG. 19  is a bottom exploded perspective view of the buffer tube and the firearm-mounting tube. 
         FIG. 20  is a front view of the buffer tube and the firearm-mounting tube. 
     
    
    
     DETAIL DESCRIPTIONS OF THE INVENTION 
     All illustrations of the drawings are for the purpose of describing selected versions of the present invention and are not intended to limit the scope of the present invention. 
     The present invention is an angle-adjustable buffer tube system for allowing fluid transitions between a primary scope or sight and a backup offset iron sight. The present invention is shown in  FIGS. 1-6  and comprises a buffer tube  1 , a firearm-mounting tube  3 , and a lockable flange assembly  6 . 
     The buffer tube  1  is an elongated tube onto which a stock may be mounted. The firearm-mounting tube  3  is the component that is screwed into the body of the firearm. For example, in the preferred embodiment of the present invention, the firearm-mounting tube  3  is screwed into the lower receiver of an AR-15 style rifle. The firearm-mounting tube  3  is able to rotate with respect to the buffer tube  1 . The lockable flange assembly  6  allows for the rotation between the buffer tube  1  and the firearm-mounting tube  3 . Additionally, the lockable flange assembly  6  is able to securely hold the buffer tube  1  in place once the firearm-mounting tube  3  has been rotated to a desired position. 
     With reference to  FIG. 7  and  FIG. 8 , the lockable flange assembly  6  comprises a flange  7 , a mounting plate  9 , a flange socket  10 , a spring-loaded ball plunger  12 , and a plurality of grooves  16 . The flange  7  is concentrically connected about a first end  2  of the buffer tube  1 , enabling the flange  7  to rotate with the buffer tube  1 . Similarly, the mounting plate  9  is concentrically and adjacently connected to a first end  4  of the firearm-mounting tube  3 , allowing the mounting plate  9  to rotate with the firearm-mounting tube  3 . The flange socket  10  traverses into the mounting plate  9  in order to accommodate the flange  7  within the flange socket  10 . The flange  7  is rotatably mounted into the flange socket  10 , enabling the firearm-mounting tube  3  to rotate with respect to the buffer tube  1 . Additionally, the flange  7  remains concentric to the flange socket  10 , ensuring that the buffer tube  1  and the firearm-mounting tube  3  remain concentrically aligned during rotation. By extension, the firearm to which the firearm-mounting tube  3  is mounted is able to rotate, allowing the shooter to tilt the firearm in a manner that facilitates the use of an offset iron sight. 
     The spring-loaded ball plunger  12  and the plurality of grooves  16  are utilized to lock the flange  7  in place within the flange socket  10  after the firearm-mounting tube  3  has been rotated to the desired position. The plurality of grooves  16  traverses into an outer lateral surface  8  of the flange  7 , allowing the plurality of grooves  16  to accommodate the spring-loaded ball plunger  12  when locking the flange  7  in place within the flange socket  10 . The plurality of grooves  16  is radially offset from each other about the outer lateral surface  8  of the flange  7 . This enables the firearm-mounting tube  3  to be rotated to one of multiple positions before being locked into place. A fixed end  13  of the spring-loaded ball plunger  12  is mounted into an inner lateral surface  11  of the flange socket  10 , ensuring that the spring-loaded ball plunger  12  is securely positioned within the inner lateral surface  11 . An engagement end  14  of the spring-loaded ball plunger  12  is retractably seated into one of the plurality of grooves  16 . This effectively locks the flange  7  in place when the spring-loaded ball plunger  12  is seated into the plurality of grooves  16 . If the shooter wishes to again rotate the firearm-mounting tube  3 , torsional force may be applied to the stock in order to overcome the lockable flange assembly  6  and dislodge the spring-loaded ball plunger  12  from the plurality of grooves  16 . 
     Again with reference to  FIGS. 1-6 , the present invention further comprises an annular retention plate  19 . The annular retention plate  19  is utilized to ensure that the buffer tube  1  and the firearm-mounting tube  3  do not become separated during use of the present invention. The annular retention plate  19  is laterally positioned around the buffer tube  1  to hold all portions of the flange  7  in place. The annular retention plate  19  is pressed against the flange  7  to securely hold the flange  7  in place within the flange socket  10 . Additionally, the annular retention plate  19  is adjacently attached to the mounting plate  9 . The annular retention plate  19  is thus able to cover both the flange  7  and the mounting plate  9  when holding the flange  7  in place within the flange socket  10 . In the preferred embodiment of the present invention, the annular retention plate  19  comprises a first separable portion  20  and a second separable portion  21 , which allow the annular retention plate  19  to be easily mounted to the buffer tube  1  by clamping the first separable portion  20  and the second separable portion  21  around the buffer tube  1 . The first separable portion  20  and the second separable portion  21  are joined together in order to cover both the flange  7  and the mounting plate  9  to hold the flange  7  in place within the flange socket  10 . The first separable portion  20  and the second separable portion  21  are positioned opposite to each other about the buffer tube  1 . As such, when the first separable portion  20  and the second separable portion  21  are joined together, the first separable portion  20  and the second separable portion  21  are able to fully encircle the buffer tube  1 . The first separable portion  20  and the second separable portion  21  may be secured to the mounting plate  9  via fasteners or a similar mechanism. 
     The present invention further comprises a male threading  22 . The male threading  22  is helically connected around the firearm-mounting tube  3  from a second end  5  of the firearm-mounting tube  3  to the mounting plate  9 . In the preferred embodiment of the present invention, the male threading  22  allows the firearm-mounting tube  3  to be screwed into the lower receiver of an AR-15 style rifle. The firearm-mounting tube  3  is screwed into the lower receiver of the AR-15 style rifle until the mounting plate  9  is positioned adjacent to the lower receiver. 
     The present invention further comprises a stock-mounting rail  23 . The stock-mounting rail  23  allows a stock to be slidably mounted to the buffer tube  1 . The stock-mounting rail  23  includes a plurality of stock-adjustment holes that allows the position of the stock to be adjusted to the shooter&#39;s comfort along the length of the buffer tube  1 . The stock-mounting rail  23  is laterally mounted along the buffer tube  1 . The shooter is able to extend or retract the stock as needed along the length of the buffer tube  1 . A neutral groove  17  from the plurality of grooves  16  is radially aligned with the stock-mounting rail  23  from the buffer tube  1 . The neutral groove  17  is the groove from the plurality of grooves  16  into which the spring-loaded ball plunger  12  is pressed when the firearm is held in a normal, non-tilted position. A tilting groove  18  from the plurality of grooves  16  is radially offset from the stock-mounting rail  23  about the buffer tube  1  by a tilting angle  24 . The tilting groove  18  is the groove from the plurality of grooves  16  into which the spring-loaded ball plunger  12  is pressed when the firearm is tilted. As shown in  FIGS. 9-12 , in the preferred embodiment of the present invention, the tilting angle  24  is 45°, vertically orienting an attached offset iron sight when the firearm is tilted. 
     The flange  7 , the spring-loaded ball plunger  12 , and the plurality of grooves  16  are shown in a neutral configuration in  FIGS. 4-8 . In the neutral configuration, the firearm is held in a normal manner and is not tilted. The neutral configuration allows the shooter to utilize a scope or other primary sight that is attached to the firearm. The engagement end  14  of the spring-loaded ball plunger  12  is pressed against the neutral groove  17 . The force provided by the spring-loaded ball plunger  12  on the neutral groove  17  prevents the flange  7  from rotating within the flange socket  10 , effectively locking the buffer tube  1  and the firearm-mounting tube  3  in place due to the presence of the spring-loaded ball plunger  12  within the neutral groove  17 . The neutral groove  17  is aligned with a central axis  15  of the spring-loaded ball plunger  12 , allowing the spring-loaded ball plunger  12  to extend from the inner lateral surface  11  of the flange socket  10  into the space provided by the neutral groove  17 . 
     The flange  7 , the spring-loaded ball plunger  12 , and the plurality of grooves  16  are shown in a tilted configuration in  FIGS. 9-12 . The tilted configuration is utilized when the shooter transitions from using a scope or other primary sight to an offset iron sight. Because the offset iron sight is oriented at an angle (most commonly 45°) from the vertical plane, the firearm is tilted in order to vertically orient the offset iron sight. In order to transition from the neutral configuration to the tilted configuration, the shooter is required to apply sufficient force to the lockable flange assembly  6  to overcome the lockable flange assembly  6  and dislodge the spring-loaded ball plunger  12  from the neutral groove  17 . The firearm may then be tilted to the desired orientation, rotating the firearm-mounting tube  3 . The buffer tube  1  remains fixed in place, keeping the stock firmly placed against the shooter&#39;s shoulder and allowing the shooter to maintain cheek weld with the stock during the tilting process. When the firearm is sufficiently tilted, the engagement end  14  of the spring-loaded ball plunger  12  is pressed into the tilting groove  18 . The tilting groove  18  is offset from the stock-mounting rail  23  and the neutral groove  17  by the tilting angle  24 , allowing the stock and the buffer tube  1  to remain unmoved while the firearm and the firearm-mounting tube  3  are tilted. The force provided by the spring-loaded ball plunger  12  on the tilting groove  18  prevents the flange  7  from rotating within the flange socket  10  after the firearm has been tilted. The buffer tube  1  and the firearm-mounting tube  3  are locked in place due to the presence of the spring-loaded ball plunger  12  within the tilting groove  18 . The tilting groove  18  is aligned with a central axis  15  of the spring-loaded ball plunger  12  and as such, the spring-loaded ball plunger  12  is able to extend from the inner lateral surface  11  of the flange socket  10  and into the tilting groove  18 . If the shooter wishes to return the flange  7 , the spring-loaded ball plunger  12 , and the plurality of grooves  16  to the neutral configuration, sufficient torsional force is applied to the stock to overcome the lockable flange assembly  6  and dislodge the spring-loaded ball plunger  12  from the tilting groove  18 . The firearm is then rotated back to the normal position. 
     In the preferred embodiment of the present invention, the flange socket  10  is designed in a manner such that the firearm-mounting tube  3  is only able to rotate in one direction. The preferred embodiment of the present invention as shown in  FIGS. 9-12  is designed for a right-handed shooter. An alternative left-handed embodiment of the present invention is shown in  FIGS. 13-17 . The left-handed embodiment includes a flange socket  10  and a plurality of grooves  16  that are designed to allow the firearm-mounting tube  3  to rotate in the opposite direction of that of the preferred embodiment. 
     As shown in  FIGS. 18-20 , the outer lateral surface  8  of the flange  7  and the inner lateral surface  11  of the flange socket  10  each comprise a first circular portion  25  and a second circular portion  28 . The first circular portion  25  and the second circular portion  28  of the outer lateral surface  8  of the flange  7  and the first circular portion  25  and the second circular portion  28  of the inner lateral surface  11  of the flange socket  10  allow the firearm-mounting tube  3  to rotate with respect to the buffer tube  1 . The first circular portion  25  of the flange  7  and the first circular portion  25  of the flange socket  10  are concentrically and coradially engaged to each other. Similarly, the second circular portion  28  of the flange  7  and the second circular portion  28  of the flange socket  10  are concentrically and coradially engaged to each other. This ensures that the flange  7  is able to snugly seat into the flange socket  10  while allowing the flange  7  to rotate within the flange socket  10 . As shown in  FIG. 20 , the second circular portion  28  is radially greater than the first circular portion  25 . This ensures that the rotation of the flange  7  within the flange socket  10  is stopped after the firearm-mounting tube  3  has been rotated to the desired position, preventing the firearm-mounting tube  3  from over-rotating. In the preferred embodiment of the present invention, an arc length  26  of the first circular portion  25  of the flange  7  is greater than an arc length  27  of the first circular portion  25  of the flange socket  10 . As a result, an arc length  29  of the second circular portion  28  of the flange  7  is less than an arc length  30  of the second circular portion  28  of the flange socket  10 . This configuration of geometric relations forms radially offset gaps between the first circular portion  25  and the second circular portion  28 . As the flange  7  rotates within the flange socket  10 , a first gap grows larger while a second gap grows smaller up to a limit, which prevents further rotation of the flange  7  within the flange socket  10 . In the opposite rotational direction, the second gap grows smaller up to a limit, which prevents further rotation of the flange  7  within the flange socket  10 . 
     As shown in  FIG. 7 ,  FIG. 8 ,  FIG. 11 ,  FIG. 12 ,  FIG. 16 , and  FIG. 17 , the user may adjust the tension of the spring-loaded ball plunger  12  through the use of a spring-adjustment screw  31 . The present invention further comprises a housing tab  32  and a screw hole  33 . The housing tab  32  is laterally connected to the mounting plate  9 , allowing the spring-loaded ball plunger  12  to be positioned within the housing tab  32 . The engagement end  14  of the spring-loaded ball plunger  12  is preferably a ball bearing while the fixed end  13  of the spring-loaded ball plunger  12  is preferably the first end of a spring  34 . The spring  34  is thus able to press the ball bearing into the plurality of grooves  16 . The screw hole  33  traverses through the housing tab  32 , up to the inner lateral surface  11  of the flange socket  10 . This allows the spring-adjustment screw  31  to come into contact with the spring  34  when the spring-adjustment screw  31  is positioned within the screw hole  33 . The ball bearing is additionally positioned into the screw hole  33 , adjacent to the inner lateral surface  11  of the flange socket  10 . This positions the ball bearing within the plurality of grooves  16  to prevent rotation of the firearm-mounting tube  3 . The spring-adjustment screw  31  is engaged into the screw hole and may be rotated to move the spring-adjustment screw  31  toward or away from the inner lateral surface  11  of the flange socket  10 . The spring-adjustment screw  31  is pressed against the first end of the spring  34 , opposite to the ball bearing. As such, when the spring-adjustment screw  31  is rotated inward toward the inner lateral surface  11  of the flange socket  10 , the stiffness of the spring  34  is increased and the ball bearing is pressed harder against the plurality of grooves  16 . Conversely, when the spring-adjustment screw  31  is rotated outward away from the inner lateral surface  11  of the flange socket  10 , the stiffness of the spring  34  is decreased and the pressure exerted on the ball bearing is decreased. 
     Although the present invention has been explained in relation to its preferred embodiment, it is understood that many other possible modifications and variations can be made without departing from the spirit and scope of the present invention as hereinafter claimed.