Patent Description:
Buffer systems in weapons, such as automatic or semi-automatic rifles for example, are designed to work together and assist a bolt carrier when it moves during the operation of the weapon. The buffer systems are typically formed and connected to the rear end of a lower receiver of the weapon, wherein the buffer contacts the rear end of the bolt carrier. When the weapon is fired, or loaded before firing, the buffer moves first backwards with the bolt carrier and then pushes the bolt carrier forward, which back-and forth movement typically achieves the required bolt action of an automatic or semi-automatic rifle.

The buffer system typically comprises a buffer tube, which is closed at rear end and open at front end, the buffer itself, and a spring, and the buffer with the spring are inside the buffer tube so, that the spring is located at least partially between the buffer and the closed end of the buffer tube. The buffer tube is typically connected to a rear of a lower receiver of a weapon via an opening formed in the lower receiver for the buffer tube with a threaded connection. The lower receiver is also equipped with a buffer retainer, which is typically a movable pin extending from the surface of the opening formed in the rear receiver for the buffer tube, and which buffer retainer prevents the spring loaded buffer to exit from the buffer tube.

The buffer retainer is typically located in a hole formed in the rear portion of the lower receiver. The hole opens partially in the area, or close to the edge of the area, of the fixing surface formed in the rear receiver for fixing the buffer tube, which fixing surface is typically formed with threading. The buffer retainer is formed as a longitudinal cylindrical piece having a smaller diameter section and a larger diameter section and a circular beveled shoulder between the sections. In the hole between the bottom of the hole and the buffer retainer is placed a spring. After the spring and the buffer retainer are placed in the hole, the buffer retainer is pushed downwards and the buffer tube is moved partially cover the hole so, that the beveled shoulder is at least partially under the edge of the buffer tube. Now, when the buffer retainer is released, the beveled collar sets against the edge of the buffer tube and the smaller diameter section extends over the thickness of the buffer tube wall to prevent the buffer located inside of the buffer tube from moving out of the buffer tube. Publication <CIT> discloses a buffer retainer pin, which is part of a buffer retainer system for keeping buffer inside a buffer tube in weapons such as AR-<NUM> rifles.

Publication <CIT> discloses a bolt carrier support system, wherein buffer retention system may comprise a body, a retention tab and a spring, which body comprises a partially annual guide portion with a channel for the retention tab. Publication <CIT> discloses a folding buttstock for firearms with recoil assemblies contained within the buttstock with buffer retainer system.

The present invention as defined by claim <NUM> provides a novel buffer retainer system, which maintains its position in the rear receiver when the weapon is dismantled. Further, the present invention provides buffer retainer system which is easy to assemble in the lower receiver of the weapon and wherein the channels formed for the buffer retainer system does not collect dirt so easily as the prior art solutions. The present invention also allows for more compact structure of the lower receiver, which lowers the overall weight of the weapon itself.

The present invention provides a buffer retainer system, which system comprises a buffer retainer and a retainer spring set in a hole formed in a lower receiver of an AR-type weapon, and wherein the buffer retainer comprises a body portion having an upper surface, and a retainer tab extending from the upper surface of the body portion and configured to extend above a surface of the lower receiver to restrict movement of a buffer of the weapon, wherein the lower receiver comprises a channel extending between the end surface of the hole and the said surface of the lower receiver, and which channel has smaller diameter than the said hole, and that the retainer tab of the buffer retainer is configured to extend via the channel in the hole.

This allows the buffer retainer to be inserted in the hole in the frame piece of the weapon via other surface of the frame piece than the surface that the retainer tab extends upwards, which allows easier assembly of the buffer retainer in the frame piece. Further, the smaller opening on the surface from which the retainer tab extends also prevents collection of dirt in the channel, since the retainer tab covers substantially greater area of the channel than in the prior art solutions. Also, no spring pin or similar part, which would be installed from the side perpendicular to the channel, is required for keeping the buffer retainer at its place, which effectively eliminates one source of dirt accumulation. In an embodiment of the buffer retainer system of the invention the system comprises a retainer screw for keeping the spring and the buffer retainer inside the said hole.

In an embodiment of the buffer retainer system of the invention the longitudinal center axis of the said hole and the said channel are parallel but not concentric.

This provides eccentric positioning of the retainer tab on the upper surface of the body portion which helps in the assembly of the buffer retainer in the lower receiver and prevents the buffer retainer rotating during the operation of the weapon.

In an embodiment of the buffer retainer system of the invention the said hole and the said channel extend substantially perpendicularly in relation to the said surface of the lower receiver of the weapon. This is a preferred embodiment, but alternatively the hole and channel can also be formed to extent non-perpendicularly if deemed necessary.

In an embodiment of the buffer retainer system of the invention the opening of the said channel on the said surface of the frame piece is in immediate vicinity of a threaded fixing surface formed in the lower receiver for a buffer tube.

More precisely the features defining a buffer retainer system in accordance with the present invention are presented in claim <NUM>. Dependent claims present advantageous features and embodiments of the invention.

Exemplifying embodiment of the invention and its advantages are explained in greater detail below in the sense of example and with reference to accompanying drawings, where.

<FIG> shows schematically an embodiment of a weapon <NUM> in which a buffer retainer system of the invention can be utilized. The weapon <NUM> show is an automatic rifle. The main parts of the weapon <NUM> in the context of the present invention are the area of the pistol grip <NUM>, buffer tube <NUM>, and the frame piece <NUM> in which the pistol grip <NUM> and buffer tube <NUM> are connected, which frame piece is a lower receiver of an AR-type rifle.

<FIG> shows schematically an embodiment of a buffer retainer <NUM> of the invention. The buffer retainer <NUM> comprises a body portion <NUM>, and a retainer tab <NUM> extending from the top surface of the body portion.

The body portion <NUM> of the buffer retainer <NUM> is preferably cylindrical in form, and the retainer tab <NUM> extending from the top surface of the body portion is located eccentrically on that surface. In other words, the longitudinal center axis of the body portion <NUM> and the retainer tab are parallel but not concentric. The eccentricity of the retainer tab <NUM> in relation to the body portion <NUM> also define the position of the buffer retainer <NUM> when in is assembled at its place in the frame piece <NUM> of the weapon <NUM>.

In the upper end area of the retainer tab <NUM> is formed a bevel <NUM>. When the buffer retainer <NUM> is assembled at its place in the frame piece <NUM> of the weapon <NUM>, the bevel will be on the side of the buffer retainer closest to a bolt carrier of the weapon <NUM>.

<FIG> shows schematically the buffer retainer <NUM> shown in <FIG> assembled at its place in a frame piece <NUM> of a weapon <NUM>. When the buffer retainer <NUM> is at its place, only the upper part of the retainer tab <NUM> extends from the surface 4a of the frame piece <NUM>, rest of the buffer retainer <NUM> is located inside the frame piece <NUM>. This outwards from surface 4a extending part of the retainer tab <NUM> also comprises the bevel <NUM>. The opposite side of the retainer tab <NUM> in relation to the bevel <NUM> keeps the springloaded buffer <NUM> inside the buffer tube <NUM>.

<FIG> shows schematically a top view of the buffer retainer <NUM> at its place in the frame piece <NUM>, as shown in <FIG>. The straight surface at the right side of the buffer tab <NUM> sets against the buffer <NUM>. The eccentric position of retainer tab <NUM> in the upper surface of the body portion <NUM> of the buffer retainer <NUM>, together with the related hole and channel formed in the frame piece <NUM> in corresponding eccentric arrangement, the larger diameter hole for the body portion <NUM> and the smaller diameter channel for the retainer tab <NUM>, keeps the buffer retainer at its position and prevents it from rotating in the channels during operation of the weapon <NUM>.

<FIG> show schematically cross-sectional views wherein the buffer retainer <NUM> is assembled at its place in the weapon.

<FIG> illustrates the situation where a bolt carrier <NUM> presses against the buffer <NUM> at its rearmost position due to firing of the weapon or due to manual loading movement of the weapon. In this position the bolt carrier <NUM> is moved inside the buffer tube <NUM> and passed the retainer tab <NUM> of the buffer retainer <NUM>. In the bottom surface of the bolt carrier <NUM> is formed a continuous groove so that the bolt carrier can pass the retainer tab <NUM> without contacting it. After the bolt carrier <NUM> has reached its rearmost position, the buffer spring <NUM> will push the buffer <NUM> and the bolt carrier forward, which forward movement of the buffer is stopped with the retainer tab <NUM> as shown in <FIG>.

<FIG> also illustrate the hole and channel formed in frame piece <NUM> of the weapon for the buffer retainer <NUM>. The larger diameter hole <NUM> is formed, preferably by drilling, via a surface of the frame piece <NUM> away from the buffer tube <NUM>, and the hole ends a distance away from the plane of the fixing surface of the buffer tube. The hole <NUM> houses the body portion <NUM> of the buffer retainer <NUM>, retainer spring <NUM>, and a retainer screw <NUM> locking the body portion <NUM> and the retainer spring <NUM> inside the hole <NUM>. As can be seen from the cross-sections shown in <FIG>, in the body portion <NUM> of the buffer retainer <NUM> is formed a recess at its bottom surface in which recess the first end of the retainer spring <NUM> is located.

The smaller diameter channel <NUM> is formed for the retainer tab <NUM>, and the channel extends from the end surface of the hole <NUM> to the surface 4a of the frame piece <NUM> so, that its opening on the surface 4a is located very near the fixing thread for fixing the buffer tube <NUM> to the frame piece <NUM>.

The hole <NUM> and the channel <NUM> are located in relation to each other in this embodiment so, that the side edges of the hole and channel that are the most away from the rear of the frame piece <NUM> coincide in a point, i.e. form a straight line extending longitudinally along the side surfaces of both the hole and the channel. In this way the channel <NUM> is completely on the area of the end surface of the hole <NUM>, but at the edge of that area. The center lines of the hole <NUM> and channel <NUM> are parallel and preferably substantially perpendicular in relation to the surface 4a, but can alternately also be formed non-perpendicularly in relation to the surface 4a.

<FIG> shows schematically an exploded view of the parts of the buffer retainer system, i.e. the buffer retainer <NUM>, retainer spring <NUM> and the retainer screw <NUM>. When assembled inside the hole <NUM>, the retainer spring <NUM> keeps the buffer retainer <NUM> at its place with its spring force, but allows manual pushing of the buffer retainer <NUM> down if the buffer <NUM> needs to be removed from the buffer tube <NUM>. The retainer screw <NUM> has threaded outer surface which allows it to be screwed in the hole <NUM> via threading formed therein.

<FIG> shows schematically how the hole <NUM> is covered with a pistol grip <NUM> when the pistol grip is fixed on the frame piece <NUM>. This prevents dirt penetrating and collecting in the area of the retainer screw <NUM> and the hole <NUM>.

Claim 1:
Buffer retainer system for a weapon (<NUM>), which system comprises a lower receiver (<NUM>) of an AR-type rifle, a buffer retainer (<NUM>) and a retainer spring (<NUM>) both set in a hole (<NUM>) formed in the lower receiver (<NUM>), and wherein the buffer retainer comprises a body portion (<NUM>) having an upper surface, and a retainer tab (<NUM>) extending from the upper surface of the body portion and configured to extend above a surface (4a) of the lower receiver to restrict movement of a buffer (<NUM>) of the weapon, whereby the lower receiver (<NUM>) comprises a channel (<NUM>) formed in the lower receiver and extending between the end surface of the hole (<NUM>) and the said surface (4a) of the lower receiver (<NUM>), and which channel has smaller diameter than the said hole, and that the retainer tab (<NUM>) of the buffer retainer (<NUM>) is configured to extend via the channel in the hole.