The present invention relates to collapsible stock assemblies for firearms, and more particularly, to collapsible rifle stock assemblies.
Various firearms, and particularly assault rifles, have been designed to include a collapsible stock. In general, such firearms include a buffer tube on which the collapsible stock is axially slidable. Some mechanism is typically included on the stock to fix its axial position on the buffer tube to allow the user to quickly adjust the effective length of the stock.
One example of such a firearm is the M-4 rifle. The M-4 is a widely used and popular rifle, and users value the ability to rapidly adjust the effective length of the stock. However, problems experienced with the collapsible stock of the M-4 rifle can be illustrative of shortcoming of current designs.
For example, while the axial position of the collapsible stock is maintained relatively securely, clearances between the stock and buffer tube often result in a loose, wobbly feel—particularly when the collapsible stock is in the fully extended position and a relatively small portion of the buffer tube is engaged within the collapsible stock. This loose, wobbly feel can be distracting to the user and adversely impact marksmanship.
This type of fit problem can be exacerbated when, as is the case with the M-4 rifle, models of a given rifle are available with varying buffer tube diameters. A collapsible stock dimensioned to accommodate larger buffer tube diameters will tend to be excessively wobbly on smaller buffer tube diameters. On the other hand, a collapsible stock dimensioned to more closely accommodate smaller buffer tubes may not fit on larger buffer tubes, at all.
Additionally, with repeated cycling of the collapsible stock assembly, wear of the stock assembly (typically plastic) against the buffer tube (typically metal) will increase clearances. Accordingly, the fit problems can become worse over time.
In view of the foregoing, it is an object of the present invention to provide an improved stock assembly. According to an embodiment of the present invention, a collapsible stock assembly for a firearm includes a stock body defining a buffer tube passage for slidably accommodating a buffer tube of the firearm therein. An adjustment slit communicates with the buffer tube passage along a forward portion thereof. A first adjustment mechanism carried by the stock body includes a buffer tube engagement element that can extend into the buffer tube passage and is selectively positionable by a first operating lever. A second operating mechanism includes a second operating lever that is operable to selectively compress the adjustment slit.
According to an aspect of the present invention, disengaging the first adjustment mechanism can operate to automatically disengage the second adjustment mechanism.
These and other objects, aspects and advantages of the present invention will be better appreciated in view of the drawings and following detailed description of preferred embodiments.
According to an embodiment of the present invention, with reference to
The stock body 20 defines a buffer tube passage 30 therein, a forward end of the passage 30 terminating at a buffer tube insertion opening 32. The buffer tube insertion opening 32 permits a rear end of buffer tube 26 to be inserted therethrough into the passage 30 along an axis thereof. The buffer tube passage 30 is dimensioned to slidably accommodate at least a portion of the buffer tube 26 therein. The buffer tube passage 30 includes an axially-extending keyway 34 along a lower side thereof to accommodate a key 36 on the underside of the buffer tube 26. The stock body 20 is preferably integrally molded from a strong and substantially rigid plastic material.
The stock body 20 additionally defines an adjustment slit 40 extending axially rearwards from the buffer tube insertion opening 32. The adjustment slit 40 communicates with a forward portion of the buffer tube passage 30 and extends radially outward therefrom. Compression of the adjustment slit 40 by the second adjustment mechanism 24 allows the buffer tube passage 30 proximate the buffer tube insertion opening 32 to clamp securely around the buffer tube 26. The capacity of the stock body 20 for flexion in this area is enhanced by a transverse slit 42 defined extending through the stock body rearward of the adjustment slit 40 and extending radially downward from the buffer tube passage 30.
The stock body 20 advantageously includes a buffer tube accommodation portion 44, in which the buffer tube passage 30 is defined, and an angled lower portion 46 extending rearwardly and downwardly from a forward end of the buffer tube accommodation portion 44. A central opening 48 is defined between the portions 44, 46. A butt portion 50 extends generally vertically between rearward ends of the buffer tube accommodation portion 44 and angled lower portions 46 and such portions surrounds and defines the central opening 48.
A sling loop 52 is formed on an upper surface of the buffer tube accommodation portion 44, defining a passage for a sling or other carrying device for the firearm. A plurality of finger grooves 54 are defined along a lower surface of the angled lower portion 46 to facilitate grasping by a user. A removable butt plate 56 snaps onto a rear surface of the butt portion 50 and is further secured thereto by a pair of spaced fasteners 60, such as screws. A bushing opening 62 is defined in an elbow between the angled lower portion 46 and the butt portion 50, and removably accommodates a bushing 64 through which a sling clip or other accessory can be pivotably routed.
Other features are defined in the stock body 20 that will be described in connection with associated components of the first and second adjustment mechanisms 22, 24.
Referring to
Referring more particularly to
The buffer tube engagement element 70 is retained within the engagement element channel 80 by an operator pin 86 inserted through the operator slot 82 and an operator bore 90 in the engagement element 70. The biasing mechanism 74 is retained in the channel 80 below the buffer tube engagement element 70 by a retention pin 92 inserted through the retention pin hole 84. The biasing mechanism 74 acts on the buffer tube engagement element 70 via a piston 94 inserted into a central bore 96 (see
Referring more particularly to
With the buffer tube engagement element 70 fully extended into one of the detents 76 of the buffer tube 26, the first engagement face 104 is initially encountered in response to forces tending to drive the stock assembly 10 forward on the buffer tube 26. The more vertical arrangement of the first face 104 provides greater resistance to such forward movement, and the angle should be set so as to prevent such movement in response to forces encountered during routine operation of a the firearm to which the buffer tube 26 is attached. For example, recoil forces should not be sufficient to overcome the engagement between any of the detents 76 with the first engagement face 104.
However, greater forces, such as incurred when inadvertently dropping the firearm on the butt plate 56 from a height of several feet or using the rifle and butt stock as a battering ram, will be great enough to drive the buffer tube engagement element 70 downwards such that the second engagement face 106 is encountered by the corresponding detent 76. The steeper angle of the second engagement face 106 results in a lower resistance to further downward movement of the buffer tube engagement element 70, thus forward motion of the collapsible stock assembly 10 will continue at an accelerated pace, overcoming engagement with any additional detents 76, until the external force is no longer applied or the stock assembly 10 reaches the physical limit of its most forward motion on the buffer tube. Thus, the collapsible stock assembly 10 can provide a self-releasing function and For act as a shock absorber to prevent damage to the buffer tube engagement element 70 if the firearm is dropped or otherwise has excessive forces applied to the butt stock or is mishandled. Also, damage to the buffer tube 26, and particularly to the detents 76, and stock assembly 10 is minimized with the use of element 70.
Referring to
Referring to
Referring to
Referring to
In
Referring to
Referring to FIGS. 2 and 19-21, the second adjustment mechanism 24 includes a second operating lever 130 having a stock body engagement portion 132 that variably engages an underlying engagement surface 134 on the stock body 20. The second operating lever 130 is pivotably mounted to the stock body 20 by one or fasteners 136, for instance a machine screw and lock nut, inserted through a second operating lever mounting bore 140 defined in the stock body 20. Advantageously, engagement surfaces 134 are formed on both sides of the stock body 20 to allow the second operating lever 130 to be mounted on either side thereof. The unused engagement surface can be covered by a blank 142.
The second operating lever 130 has a first end 144 and a second end 146. The first end 144 carries the stock body engagement portion 132 and defines a central mounting bore 150 for receiving the fasteners 136. Advantageously, a portion of the mounting bore 150 can be hexagonal to closely accommodate a nut therein. The second end 146 extends rearwardly from the first end 144 and can be contoured and textured for easy manipulation by a user.
The stock body engagement portion 132 carries a plurality of engagement teeth 152 that extend from the second operating lever 130 first end 144 toward the stock body 20. The engagement surface 134 includes a plurality of adjacent high and low zones 154, 156 underlying the engagement teeth 152. With the second operating lever 130 pivoted via manipulation of the second end 146 such that the teeth 152 overlie high zones 156, the adjustment slit 40 of the stock body 20 is compressed (as in
To release the second adjustment mechanism 24, the second end 146 is urged downwardly, in the direction of arrow 160 (as in
As seen in
Because the operator pin 86 and the first operating lever 72 second end 114 extend on both sides of the stock body 20, automatic disengagement of the second adjustment mechanism 24 will occur regardless of the side on which the second operating lever 130 is mounted. The second operating lever 130 second end 146 can also include operator pin grooves 162 (see
From the foregoing, it will be appreciated that a collapsible stock assembly according to the present invention allows quick re-positioning of the stock body according to the needs or preferences of a user without sacrificing the solid feel. Additionally, the addition of the second adjustment mechanism 24 is accomplished without requiring any additional user actions to disengage. Moreover, the useful life of the collapsible stock assembly is increased, as increased play resulting from wear in adjustment mechanisms can be avoided by simply tightening the fasteners 136 to adjust the tension exerted by the second adjustment mechanism 24. Also, if wear does occur, the second adjustment mechanism 24 may be able to compensate for such wear thereby extending the useable life of the butt stock and/or the rifle buffer tube 26.
For some firearm models, buffer tubes are available in multiple sizes. For example, for AR/M4 stocks the buffer tubes come in a Mil-Spec size and a slightly larger Commercial size. For many collapsible stocks, this means either a different stock must be used for different buffer tube sizes, or additional looseness is experienced when using the stock on a Mil-Spec buffer tube.
The collapsible stock assembly 10 can advantageously include sizing components to ensure a close fit for multiple sizes. Referring to
Referring to
Referring to
If the collapsible stock assembly 10 is to be used with a large buffer tube, the sizing shim 170 is removed and the sizing pin 172 is removed and reinstalled with the first sizing face 190 oriented upwardly. The key of the larger buffer tube can extend all the way to the bottom of the keyway 34. As will be appreciated, the sizing components thereby allow the collapsible stock assembly 10 to accommodate buffer tubes of multiple sizes without sacrificing a firm, reliable fit.
In general, the foregoing description is provided for exemplary and illustrative purposes; the present invention is not necessarily limited thereto. Rather, those skilled in the art will appreciate that additional modifications, as well as adaptations for particular circumstances, will fall within the scope of the invention as herein shown and described and the claims appended hereto.
This application is a continuation-in-part of U.S. patent application Ser. No. 29/375,873, filed on Sep. 29, 2010, now U.S. Pat. No. D668,311 the contents of which are herein incorporated by reference in their entirety.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US2011/049396 | 8/26/2011 | WO | 00 | 3/25/2013 |
Publishing Document | Publishing Date | Country | Kind |
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WO2012/050670 | 4/19/2012 | WO | A |
Number | Name | Date | Kind |
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7823313 | Faifer | Nov 2010 | B2 |
8555541 | Ingram | Oct 2013 | B2 |
8782941 | Zusman | Jul 2014 | B2 |
20100242333 | Kincel | Sep 2010 | A1 |
20130097911 | Larue | Apr 2013 | A1 |
Number | Date | Country | |
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20130180148 A1 | Jul 2013 | US |
Number | Date | Country | |
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Parent | 29375873 | Sep 2010 | US |
Child | 13825942 | US |