Folding buttstock for firearms with recoil assemblies contained within the buttstock

This application is related to U.S. Provisional Application Ser. No. 61/561,249 entitled “FOLDING BUTTSTOCK FOR FIREARMS WITH RECOIL ASSEMBLIES CONTAINED WITHIN THE BUTTSTOCK” filed on 17 Nov. 2011 and to U.S. application Ser. No. 13/680,308 filed on 19 Nov. 2012, and to U.S. application Ser. No. 14/672,402 filed on Mar. 30, 2015, all three of these applications are incorporated by reference herein in their entireties.

Compactly storing a firearm is a challenge. This is especially the case for firearms such as M-16/AR-15/AR-10 types which have mechanisms that use direct gas impingement. Many M-16 type weapons have a direct gas impingement system, and could benefit from being able to fold the stock; however, suitable mechanisms permitting a folding stock in a direct gas impingement system have not been developed.

Folding stocks are known. US Patent Application No. 201010307042 shows a modular firearm stock system which includes a foldable butt stock assembly. U.S. Pat. No. 7,966,761 shows an automatic or semiautomatic rifle with a folding stock. Similarly, US Patent Application No. 2011/0131857 shows an automatic or semiautomatic rifle with a folding stock which is the same as in U.S. Pat. No. 7,966,761. U.S. Pat. No. D636,834 shows simply a folding firearm stock without internal details. US Patent Application No. 2010/0212206, and U.S. Pat. Nos. 7,827,721 and 7,673,412 show folding stock assemblies that do not accommodate any mechanisms. U.S. Pat. No. 7,418,797 shows another simple foldable rifle stock which has an added adjustable cheek pad. These foldable butt stock assemblies simply function as foldable stocks and do not accommodate any actuation.

Firearms which incorporate hinges are also known. U.S. Pat. No. 7,802,392 teaches tactical firearm systems, and methods of manufacturing same, which includes a modular locking hinge having two parts that attach modular components; however, the hinge does not appear to be used for a foldable stock. U.S. Pat. No. 6,591,533 shows a locking hinge used with a folding shoulder rest for a paintball gun which basically is analogous to a rifle stock for a handgun.

Direct gas impingement systems in M-16 type weapons bleed combustion gas from the barrel and convey it through a hollow tube back to the weapon's upper receiver. The gas from the tube pushes rearward on the bolt carrier assembly that rides within the upper receiver. The rearward push on the bolt carrier assembly, and attached bolt, cause the assembly to move rearward. The rear of the bolt carrier assembly bears against a recoil buffer and associated spring which are contained within the buffer tube, buttstock, or a receiver extension. When the bolt travels rearward, it compresses the buffer spring; it is this force combined with the weight of the buffer which slows, and then stops, the bolt carrier assembly's rearward movement. The direction of movement then reverses, and the carrier assembly travels forward again, back into battery.

Aspects of the present invention are directed to a folding buttstock for firearms with recoil assemblies contained within the butt stock or equivalent. The buffer and recoil spring are retained within a buffer tube of the butt stock so the stock can fold. The innovation provides a device that bisects the buffer tube by providing a hinge there between. In operation, the buffer and buffer spring may be retained within the butt stock when the butt stock is folded back. The bolt carrier is not physically attached to the buffer and recoil spring, but instead, the bolt carrier and buffer spring merely bear against each other. The present invention is described by way of a buttstock with a shoulder rest; however, weapons that only have a rearward extending buffer tube without the shoulder rest are included.

Folding stocks are desirable on firearms because they make them easier to store and transport. There are no folding stocks available for conventional M-16 style rifles and pistols which utilize direct gas impingement. The present design retains the buffer and spring within the folded stock, and makes it possible to have an M-16 style rifle with a folding stock. A folding stock assembly which contains the buffer and buffer spring within the folded portion of the stock for a firearm that uses a direct gas impingement system.

To actuate the bolt carrier assembly and related appurtenances, in this style of firearm, there is a recoil buffer (weighted cylinder) and spring which are contained within a buffer tube. The buffer tube forms part of such weapon's buttstock, and extends therefrom towards the muzzle end of the weapon. The buffer travels within the buffer tube in response to the recoil of the weapon upon firing.

A manually operated hinge release mechanism may be used to both allow hinge movement operation and to activate or actuate the system which retains the buffer within the butt stock. Additionally, these two operations could utilize separate controls whereby one controls the hinge opening/closing and the other controls the mechanism used to retain the buffer/spring within the buttstock. A manually operated mechanism is utilized to lock the buffer tube hinge closed, or straight, position so that the weapon may be operated. Further, retainer devices may be utilized to hold the buffer tube in an open, or folded, position. If desired, one or more gaskets or seals can be present between different hinge sections to reduce the likelihood of entry of foreign material into the space where the hinges mate. In some instances, a series of gaskets can be stacked upon each other to provide a desired height or depth. For example, one or more O-rings or similar devices can be placed between different hinge sections. In some configurations, one or more devices may be placed in-line with the buffer and comprise an aperture where the bolt carrier may slide through to clean debris off of the bolt carrier.

These and other aspects of the present invention will become readily apparent upon further review of the following drawings and specification

Similar reference characters denote corresponding features consistently throughout the attached drawings.

A folding stock assemblycontains a buffer tube folding mechanism, an embodiment of which is shown in, with a bufferand a buffer springdisposed within a buffer tubewithin the folded portion of the stockfor a firearmthat uses a direct gas impingement system. A buffer tube folding mechanismis provided which has first and second collarsand, hingedly attached to one another, with openings there through. If desired, one or both of the collars,can include a gasket or seal (such as gasketon the collar) disposed on a suitable surface such that when the collars,are adjacent to each other in the closed position the gasket(s) acts to reduce the likelihood that foreign material, e.g., dirt, sand, etc. will enter into any space between the collars,. In some instances, the gasket can take the form of a replaceable O-ring or similar ring that can be inserted around the collars,or in one or more depressions or grooves within the collars,. For example, one or both of the collars,may include a machine groove configured to receive an O-ring by way of a friction fit. A surface of the O-ring may protrude from the face of the collar to act to seal the space between the two collars,. In other instances, the gasket or seal is generally flat, e.g., takes the form of a washer such as a nylon or stainless steel washer, and can be attached to the collar using an adhesive, welded on or otherwise disposed on one or both of the collars,. The gasket may have similar dimensions as the collaroror may be larger or smaller. If desired, one or both collars may also comprise a “wiper” or cleaning device comprising an aperture. The cleaning device can be sized and arranged to permit the bolt carrier or buffer to slide through the aperture and engage the outer surfaces of the bolt carrier and/or buffer to at least some degree to clean debris off of the outer surfaces of the bolt carrier and/or buffer. The cleaning device may comprise brushes, whiskers, fibers, hairs or other projections that can clean off debris from the bolt carrier and/or buffer as these components reciprocate during operation of the weapon. A buffer retaineris shown ifto retain the buffertherein.in greater detail shows, a buffer tubeof a butt stockis attached to the rear hinge block, which is the first collar. The buffer retainer, shown in, has a plungeris contained in the collarjust below the opening there through, and the plungeris pushed upward by plunger springwhen the collarsandare not closed. The plungerprotrudes into opening of the collarand prevents the bufferand springfrom falling out.

When the collarsandare closed for use as shown in, the retainer actuatorengages plungerand pushes it downward due to the angled openingin the plunger. Actuatormay have a roller tip or other means of reducing friction (not shown) when it contacts plunger. Plungermay also have bearings where it is engaged by actuator. Additionally, the plungermay have bearings on its exterior to reduce the friction when it moved up/down within its opening. The openingthrough which plungermoves may also have bearings.

The first collaris shown inas threading into a first receiver. A modified standard lock ringis shown with a hole threaded throughto accept a screw (not shown for clarity) which will prevent the first collarfrom rotating. There are many other possible methods for preventing the collarsandfrom rotating.

shows that the first collarmay have a standard buffer tubeof butt stockinstalled using the conventional lock ringwith a castle nut. Other methods would also work and these elements have generally been omitted from the other figures for the sake of clarity. Additionally, the first collarmay be connected to the lower receiverin several different ways. The second collarmay contain an integral threaded tube which would screw into the lower receiver in the same manner as a standard buffer tubeor it may utilize a separate threaded tube which would thread into both the lower receiverand the second collar. If necessary to help the threads index such that the second collaraligns properly with the lower receiver, then a spacer or spacers of variable thickness could be used in place of or to augment a lock ring.

is a top view of the elements shown in, except that it also shows a hinge. The elements are shown in both their folded and unfolded positions. A weaponhas a folding stock assemblywith a bufferand a buffer springretainable within the folded butt stock. The buttstockfolds laterally on hinges, as demonstrated in, connected on the side thereof. Where a gasket or seal is present on one of the collars,, closing of the hinge to the position shown incan act to compress the gasket, e.g., compress the O-ring, to seal the space between the collars,.

The innovative design described in this application retains the bufferand recoil springwithin the folded butt stockin the first collaron the buffer tubeof the buttstock. There are alternative ways to retain the bufferand recoil springwithin a folded butt stock, each blocking the opening at the first collarretaining the buffer.show an alternative retainer mechanismthat is biased upwards to block the motion of the buffer. The retainer mechanismis actuated by closing the collarsandwhereupon the retaineris withdrawn permitting unhindered movement of the bufferand spring.shows a different arrangement to actuate the plungerwhich utilizes a connecting rodand a bellcrank. When the stockis folded to the side, the bellcrank springmoves within the recess shown, and pushes the connecting rodand plungerupward. This retains bufferand springwithin the buffer tubeof the butt stock.shows that when the stock is unfolded to the rear, the actuatorpresses on the bellcrankwhich causes it to pivot as shown. This puts tension on connecting rodand pulls plungerdownward, thereby allowing the bufferand buffer springto move unhindered to bear against the bolt carrier assembly (not shown). Where a gasket or seal is present, the gasket or seal can desirably be sized and arranged such that interference with the actuator (or other comparable means) does not occur.

Note that all the previous figures show a protrusion from the plungerat the six o′clock position into the buffer tubeof the buttstockwhich retains the bufferand springwhen the stockis folded. Note that there is a recess in the conventional bolt carrier assemblywhich allows the bolt carrier assemblyto pass over the protrusion and into the buffer tubeof the buttstock. The bufferdoes not have such a recess and therefore cannot pass over the buffer retainer.

Conventional wisdom had deemed it impossible for known M-16 style weapons which are shown into have a folding buttstock. The various embodiments of the present design work because the bolt carrieris not physically attached to the bufferand recoil spring. Instead, the bolt carrierand buffer springmerely bear against each other. When the weapondischarges and the bolt carrier mechanismis actuated, it is pushed partially into the buffer tubeof the butt stockthereby forcing the bufferrearward and compressing the buffer spring. After the springstops the rearward motion of the bufferand bolt carrier assembly, it forces them forward and reloads the weapon.

The design of the present invention system is applicable to other weapons beyond the M-16 family of firearms, and is not limited to those style weapons. Indeed, any weapon which contains part of its operating mechanism within the butt stock could potentially benefit from the present design. When the stockis folded, the bolt carriermay still travel rearward and protrude from the weapon, but is prevented from falling out by the charging handle and lower receiver.

The same methods which are used to retain the bufferand springassembly within the butt stockare adapted to retain the bolt carrierdeeper within the weapon's receiver and prevent much of its rearward movement. This may be accomplished automatically upon folding/unfolding the stockor with some assistance from the user. Another approach to retaining the bolt carrierassembly deeper within the receiver is to pull the trigger after the stock is folded open after ensuring that the weapon is unloaded. This would allow the hammer to pivot forward and retain the bolt carrier assemblycompletely forward within the upper receiver.

Yet another approach to retaining the bolt carrier assemblydeeper within the receiver is a simple plug made from plastic, rubber or a similar material. It could be easily inserted by the user and removed before the stock is unfolded. A variation of this would be two plugs which could be joined together by a string, rubber band, or similar material. One would fit into the receiver as described above and the other would fit into the first collarin folded butt stock. These would also serve to keep dirt and other contaminants out of the operating mechanisms.

In operation, the user retracts the charging handle to move the bolt carrier assembly and buffer rearward while compressing the buffer spring. Once the bufferhas been moved rearward so that it is within the first collar, also called the rear hinge blockin the examples, the hingewould be opened and the retainerwould rise to retain the bufferwithin the butt stock. The stockis then completely folded and the user gives a slight push forward to the bolt carrier assembly. Alternatively, the user could push the built-in forward assist on the upper receiver, as is well known.

Unfolding the stocksimply entails the user closing the hinge. The internal workings of the design can be timed to retract the retainer mechanismand release the bufferand springassembly to move forward once the buttstockwas adequately closed. Alternately, the retainer mechanismfor the bufferand springcould be made to require a specific manual input from the user other than simply closing the stock. If desired, one or more gaskets or seals can be present within or around the retainer mechanism to avoid foreign material entering that space and potentially interfering with proper operation of the retainer mechanism. As noted herein, the retainer mechanism may include, or be configured to receive, a wiper or cleaning device to remove debris from outer surfaces of the bolt carrier and/or buffer. In some instances, the wiper is removable and can be replaced, e.g., by removal of an old wiper and insertion of a new wiper by friction fit.

The stock shown in the drawings folds to the left side, but the design is applicable to all directions including the right (ejection port) side, over the top, or under toward the magazine. A lower receiver which incorporates the elements necessary to allow an integral folding stock mechanism may also be used. The design would allow the use of existing AR-stocks or buffer tubes, but other designs could be created. The hinge blocks and mechanism could cause a slight increase in the distance between the rear of the bolt carrier assembly when it is battery and the inside rear of the butt stock or buffer tube. This would create less pre-load on the buffer spring and could affect the weapon's functionality. To offset this distance, a spacer could be added to the rear of the buffer spring. Alternately, the spacer could be located on the buffer itself. A longer buffer spring or one with a modified spring rate could also be created to perform the same function, as could a modified buffer. A shorter butt stock or buffer tube would serve the same purpose. The design could incorporate a safety mechanism that would prevent the weapon from discharging if the stock is folded

show an embodiment of a hinge and retainer mechanism according to an alternative embodiment of the current design.show another embodiment which utilizes an armwhich rotates forward and rearward. When the stockis folded to the side as in, the armis held in the forward position by a torsion spring. A compression spring similar toincould also be used. When the stockis unfolded to the rear, the actuatorrotates armrearward and releases the bufferand spring.

also show a different folding mechanism. In this configuration, the second collaroverlaps the first collarwhen the stockis unfolded. This may add rigidity to the system and may also keep foreign material out of the system. This configuration could be applied to the other embodiments as well. If desired, a gasket or seal can be present on one or both of the collars shown into assist in creating a tight lockup between the collars and/or preventing entry of foreign material into the space. As noted herein, one or both collars may comprise, or be configured to receive, a wiper or cleaning device to remove debris from outer surfaces of the bolt carrier and/or buffer. In certain examples, the wiper is removable and can be replaced, e.g., by removal of an old wiper and insertion of a new wiper by friction fit.

show an embodiment of a hinge and retainer mechanism according to an alternative embodiment of the current design. This embodiment utilizes an armwhich rotates forward and rearward. When the stockis folded as in, the armis held in the forward position by a torsion springwhich must be strong enough to overcome the forward force exerted by the buffer spring. A compression springsimilar as used elsewhere could also be used instead of the torsion springand other spring types may also work satisfactorily, as is well known. When the stockis unfolded to the rear as in, the actuatorrotates armrearward and releases the buffer.

shows an alternative design of retainer mechanismusing a v-springwith a tipattached thereto, although a flat spring or leaf spring would suffice. When the stockis folded to the side, the v-springexpands and its tip protrudes into the first collarof the buffer tubewhich retains the bufferand spring. When the stockis unfolded for use, the actuatoron the second collarcompresses the spring. The v-springmust be strong enough to overcome the forward force exerted by the buffer spring. (44) Pivot pins, torsion springs, leaf springs, tension springs, and compression springs are also usable according to various embodiments of the present design, and all are designated by the numeralhereafter.shows an alternative design of retainer mechanism using a pivot pin.shows an embodiment that utilizes a v-springwith a tipwhich protrudes into the first collaradjacent the buffer tubewhen the stockis folded. When the stockis unfolded to the rear, the v-springis compressed by the opening and notchin the second collarwhich lowers the tipand releases the bufferand spring. A roller or ball bearingas well as other types of bearings may be used to reduce the friction between the v-springand the notched opening. Additionally, the v-springmay be depressed by an actuatorprotruding from the first collar, as shown in, instead of an opening and notchwithin the second collar. When the stockis unfolded for use, the openingon the second collaris configured to pinch the springwhich retracts the tipfrom within the first collaradjacent the buffer tubeallowing the bufferand springto move forward to meet the carrier.

show an alternative design of a collar(either the first collaror the second collar) to mate with the adjacent parts of the buffer tubeto form a single buffer tubewith the folding mechanismwhen unfolded. When the stockis folded, the collet release ringis not in contact with the collet fingers. The collet fingerswhich are attached to a collet ringare springy and their normal state is contracted such that they protrude into the open interior diameter of the buffer tube. This effectively reduces the diameter and prevents the buffer/spring (not shown) from moving forward and exiting the first collar. When the butt stockis unfolded, the collet release ringputs pressure on the collet fingersand flexes them outward, away from the inner diameter of the buffer tube. This increases the effective diameter and allows the buffer and spring assembly (not shown) to move forward. Note that four collet fingersare shown, but more or fewer could also be used. Additionally, the collet fingerscould have tipswhich would protrude and create a shoulder which would offer more positive retention of the buffer/spring.

(46) Closer details of the hinge and retainer mechanisms are depicted throughout for reference only; numerous alternative designs of hinges are well known.show a hinge mechanismfor a folding buffer tubeaccording to alternative embodiments of the present design. The mechanismmay be adapted to accommodate either a folding buttstockwhich retains part of the firearm's operating system within the butt stock, or it may accommodate a folding buttstockthat does not retain any of the firearm'soperating system within the buttstock.

show the device with the butt stocklocked into the folded position by the outboard detent ball. The plunger rodis springloaded and has cutoutswith ramps that apply upward force to the detent ballsuntil the plunger rodis depressed, at which time it slides toward the hingeexposing the detent ballsto cutoutswithin the plunger rod. At this point, the collarsandcan be rotated about the hingeto fold or unfold the buffer tube. When the unit has been rotated 90 degrees+/−about the hinge, and the plunger rodis released by the user, the detent ballswill be pushed upward by the plunger rodand into cutoutswithin the first collar. Releasing pressure from the plunger rodwill cause it to be forced outward by the plunger return springwhich will again push the detent balls upward into the cutoutsin the first collar. Note that the unit could be structured such that the detent balls are contained within the second collarinstead of the first collar.

When the plunger rodis depressed, the plunger return springbecomes compressed into a recess within the plunger rod. The plunger rodslides linearly within the first collarinside a cutout partially depicted for clarity as. An alternative version of the plunger rodwhich could be used, and operates as follows: wherein the rod is still circular, but only has the recesses for the detent balls on top. It may have a folding lever that protruded from the end. When the lever is rotated, it would rotate the plunger rod and either cam the detent balls upward or release them. If desired, this may be linked to the apparatus which retains bufferwithin the butt stock.

The cutoutswithin the plunger rodcould surround the around the entire circumference of the plunger rod, as shown in. The hinge pinpenetrates an opening in the plunger rodwhich is large enough so the hinge pindoes not interfere with the movement of the plunger rod. Instead of individual cutoutswithin the first collar, a single v-shaped cut could be created along the length of the first collar'shinge blockin. The openingwould accommodate movement of the bolt carrier group through the first and second collarsand, and into the buffer tubeif used on an M-16/AR-15 type weapon system.

show the unit with the stock unfolded to the rear. In, the detent ballsare shown being pushed upward into the first collarby the plunger rodwhich locks the first and second collarsandtogether. In, the detent ballsare shown as being located downward, inside the second collaras if the plunger rodis being depressed. This would free the collars (and) to rotate about the hinge.

show an environmental view of an example folding stock assembly, and a weaponhaving a folding stock assemblyin a folded position.show the operation of the retainer mechanismused in the example of.shows the retainer mechanismis position to retain the bufferand spring.

shows an illustration of the wiper or cleaning device. A buffer(or the bolt carrier if desired) can slidingly engage inner surfaces of the wipersuch that debris is removed by the wiper. The wipermay comprise fingers or projections that contact outer surfaces of the buffer(or the bolt carrier or both) to clean the buffer as it reciprocates during operation of the weapon.

It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.