Patent Description:
Certain embodiments provide a cam race having a hardened surface along which a cam pin slides during a firing operation of a bolt action firearm. The hardened surface minimizes the likelihood of undue wear on components of the firearm (e.g., on the interior surface of the upper receiver of the firearm). The cam race is a separate component, comprising a different material composition (a harder material composition) than the upper receiver to which the cam race is secured. The cam race may be riveted onto the upper receiver, within a slot defined within an interior surface of the upper receiver. The cam race with the fastener pins (to be deformed into rivets) may be integrally formed, thereby minimizing excess parts (e.g., separate fastener components) and ensuring a strong connection between the cam race and the upper receiver.

Certain embodiments are directed to a cam race for an upper receiver of a firearm, the cam race comprising: a body defining a slide face and an opposite rear face; and a plurality of fastener pins extending away from the opposite rear face, wherein the plurality of fastener pins are integrally formed with the body; and wherein the body and the plurality of fastener pins comprise a material selected from: steel or titanium.

In certain embodiments, each of the plurality of fastener pins extend between a base end connected with the opposite rear face and a distal end, and wherein the distal end of each of the plurality of fastener pins is configured for deformation to form a rivet. In some embodiments, the body and the plurality of fastener pins are nitride finished.

Various embodiments are directed to an upper receiver assembly for a firearm in accordance with claim <NUM>, the upper receiver assembly comprising: an upper receiver defining a groove within an interior sidewall, wherein the groove defines a plurality of through-holes extending through the interior sidewall of the upper receiver to an exterior sidewall of the upper receiver, wherein the exterior sidewall defines a raised rail that is aligned with the groove such that the groove at least partially extends into the raised rail; and a cam race comprising: a body defining a slide face and an opposite rear face, wherein the body is positioned within the groove; and a plurality of fastener pins extending away from the opposite rear face, wherein each of the plurality of fastener pins extend through a corresponding through-hole.

In various embodiments, each of the plurality of fastener pins extend between a base end connected with the opposite rear face and a distal end, and wherein the distal end of each of the plurality of fastener pins is deformed at the exterior sidewall of the upper receiver to form a rivet. In some embodiments, the distal end of each of the plurality of fastener pins is at least substantially planar with the exterior sidewall of the upper receiver. In some embodiments, the distal end of each of the plurality of fastener pins extends beyond the exterior sidewall of the upper receiver. In various embodiments, the exterior sidewall defines a countersink surrounding each of the plurality of through-holes. In certain embodiments, the upper receiver comprises a first material and the cam race comprises a second material; wherein the second material is harder than the first material. In some embodiments, the cam race comprises a hardened steel material.

Certain embodiments are directed to a firearm comprising an upper receiver assembly as described herein.

Certain embodiments are directed to a method of manufacturing an upper receiver assembly for a firearm in accordance with claim <NUM>, the method comprising: forming an upper receiver defining a groove within an interior sidewall, wherein the groove defines a plurality of through-holes extending through the interior sidewall of the upper receiver to an exterior sidewall of the upper receiver, wherein forming an upper receiver further comprises forming a raised rail at the exterior surface of the upper receiver, wherein the raised rail is aligned with the groove such that the groove at least partially extends into the raised rail; placing a cam race within the groove, wherein the cam race comprises: a body defining a slide face and an opposite rear face, wherein placing the cam race within the groove comprises placing the body within the groove; and a plurality of fastener pins extending away from the opposite rear face, wherein placing the cam race within the groove comprises placing each of the plurality of fastener pins through a corresponding through-hole; and securing the cam race within the upper receiver via the one or more fastener pins.

In some embodiments, securing the cam race within the upper receiver via the one or more fastener pins comprises deforming a distal end of each of the one or more fastener pins to form a riveted connection between the cam race and the upper receiver. In various embodiments, the method further comprises smoothing the distal ends of each of the one or more fastener pins to be at least substantially planar with the exterior sidewall of the upper receiver. In certain embodiments, deforming a distal end of each of the one or more fastener pins comprises: threading the upper receiver onto a support rod such that a surface of the support rod is in contact with the slide face of the cam race; and compressing the distal end of each of the one or more fastener pins via a press to provide a compressive force on each of the fastener pins between the support rod and the press. In certain embodiments, the method further comprises forming the cam race from a material harder than a material of the upper receiver. In various embodiments, forming an upper receiver further comprises forming countersink surrounding an exterior end of each of the plurality of through-holes.

The present disclosure more fully describes various embodiments with reference to the accompanying drawings. It should be understood that some, but not all embodiments are shown and described herein. Indeed, the embodiments may take many different forms, and accordingly this disclosure should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements.

A firearm as discussed herein is a bolt-action gun for discharging a projectile. As a specific example, a firearm is a rifle, such as an AR-<NUM>, AR-<NUM>, M-<NUM>, SR-<NUM>, or a variant thereof. However, it should be understood that other firearms may benefit from the configurations discussed herein, and therefore this description should not be construed as being limited in applicability to a single type of firearm.

The receiver assembly <NUM> encompasses an upper receiver <NUM> and a lower receiver <NUM>. The receiver assembly <NUM> houses operational components of the firearm, such as components of the firing mechanism for the firearm. In some embodiments, the receiver assembly <NUM> houses a spring-biased hammer that is cocked and then released by a sear upon actuating a trigger mechanism within the lower housing <NUM>. The hammer strikes a firing pin carried by a bolt <NUM> (the bolt <NUM> being carried by a bolt carrier <NUM>), which is thrust forward within the upper receiver <NUM> to contact and discharge a cartridge loaded within a chamber to propel a projectile through a barrel of the firearm. Within certain firearms, a portion of the expanding combustion gases traveling down the barrel is discharged off and used to drive the bolt rearward against a forward biasing force of a recoil spring for automatically ejecting the spent cartridge casing and automatically loading a new cartridge into the chamber from a magazine when the bolt returns forward.

The upper receiver <NUM> defines an internal, longitudinally-extending cavity (extending parallel to the length of the firearm, in a direction parallel to the travel of a projectile exiting the firearm) configured to receive a bolt carrier <NUM> and bolt <NUM> (collectively, a bolt assembly). The bolt assembly is slidably positioned within the internal cavity of the upper receiver <NUM> for axially reciprocating recoil movement therein.

The internal cavity of the upper receiver <NUM> is defined by cavity sidewalls. A portion of the cavity sidewalls are contoured to the generally cylindrical shape of the bolt assembly to enable smooth sliding of the bolt assembly within the internal cavity. An upper portion of the internal cavity is shaped to accommodate a cam pin <NUM> extending upward from an upper portion of the bolt carrier <NUM>. The cam pin <NUM> maintains appropriate rotational positioning of the bolt assembly during reciprocal movement of the bolt assembly. In some firearm configurations, the bolt assembly is biased toward a counterclockwise rotation (when viewed in the direction of projectile travel) within the internal cavity of the upper receiver <NUM>. This rotational biasing force on the bolt assembly presses the cam pin <NUM> against an interior sidewall of the upper receiver <NUM> (e.g., an at least substantially planar portion of the interior sidewall). During reciprocal movement of the bolt assembly during firing, the cam pin <NUM> remains in contact with the interior sidewall of the upper receiver <NUM>, and slides along the interior sidewall of the upper receiver <NUM> along an at least substantially linear cam pin travel path extending between a rear position (corresponding to the most-rearward position of the cam pin <NUM> during recoil movement of the bolt assembly) and a forward position (corresponding to the most-forward position of the cam pin <NUM> during a firing action of the bolt assembly).

As shown in the cutaway view of <FIG>, the cam pin <NUM> slides along a slide face of a cam race <NUM> secured within a groove of the interior sidewall of the upper receiver <NUM>. The cam race <NUM> comprises a hardened material resistant to scoring, etching, scratching, denting, or the formation of other defects within a surface thereof. As noted above, the cam pin <NUM> is biased against the interior sidewall of the upper receiver <NUM> (specifically, against the slide face of the cam race <NUM>). During use of the firearm, dirt, material slivers from spent casings, and/or other undesired contaminants (e.g., particles) may become lodged between a surface of the cam pin <NUM> and the slide face. Given the biasing force pressing the cam pin <NUM> against the slide face, an unhardened surface may become etched or otherwise defective as these small particles are trapped between the cam pin <NUM> and the interior sidewall of the upper receiver and they slide with the cam pin <NUM> along the interior sidewall of the upper receiver <NUM>. While regular cleaning of the firearm mitigates the likelihood that these small contaminants are present within the upper receiver (thereby minimizing the likelihood that these contaminants can become lodged between the cam pin <NUM> and the interior sidewall of the upper receiver <NUM>), there remains a risk that these contaminants can become undesirably lodged within components of the firearm during even short periods of use (particularly when used in inhospitable environments (e.g., dusty/dirty environments with high levels of particle contaminants in the air). Thus, providing a hardened slide face along which the cam pin <NUM> slides during use of the firearm further mitigates potential damage to the interior surface of the upper receiver <NUM> that may cause malfunction of the firearm.

As an example, the cam race <NUM> comprises a steel material, such as a hardened stainless steel. The hardened steel material of certain embodiments is a steel alloy, such as <NUM> steel alloy. In certain embodiments, the hardened steel material is further treated (e.g., after forming the cam race <NUM>) to provide additional durability. Other example materials comprise titanium, carbon steel, other steel alloys, and/or other materials that are highly wear-resistant. At least a portion of the cam race <NUM> is heat treated. At least a portion of the cam race <NUM> is polished and/or has a nitride finish to provide desired frictional properties to facilitate sliding of the cam pin <NUM> along the slide face. It should be understood that other finishing techniques, surface treatments, and/or the like may be provided to the cam race <NUM> to provide desired surface properties of the cam race <NUM>. Moreover, it should be understood that other hardened materials may be formed into the cam race <NUM>, provided that the other hardened materials are sufficiently durable to mitigate the likelihood of damage to the surface of the cam race <NUM> that may result from contaminants trapped between the cam pin <NUM> and slide face during typical use of the firearm.

Compared with the material of the upper receiver <NUM> (e.g., typically an aluminum material for weight saving), the cam race <NUM> provides increased durability to the firearm, with a negligible increase in weight to the firearm.

<FIG> illustrate an example cam race <NUM> isolated from other components of the firearm. As shown in <FIG>, the cam race <NUM> is an elongated component - having a length equal to or longer than the linear cam pin travel path discussed above. The cam race <NUM> has a body <NUM> defining a slide face and an opposite rear face. The thickness of the body (between the slide face and the opposite rear face) corresponds to a depth of a groove <NUM> into which the cam race <NUM> is installed within the interior surface of the upper receiver <NUM>, such that the slide face is at least substantially planar with the interior surface of the upper receiver <NUM> when installed therein. In other embodiments, the slide face protrudes relative to the interior surface of the upper receiver <NUM>. As shown in <FIG>, a front end and a rear end (on opposite ends of the length of the cam race <NUM>) of the slide face are chamfered, to facilitate movement of the cam pin <NUM> across the front end or the rear end of the slide face in the event the cam pin <NUM> travels beyond the linear cam pin travel path.

The cam race <NUM> has a height (measured perpendicular to the length and the thickness) sufficient to ensure the cam pin <NUM> does not contact the interior surface of the upper receiver <NUM>, and/or to ensure that contaminants cannot be caught directly between the cam pin <NUM> and a portion of the interior surface of the upper receiver <NUM>. For example, the cam race <NUM> of certain embodiments has a height larger than a height of the cam pin <NUM> (or at least larger than a contact surface of the cam pin <NUM> that directly contacts the interior sidewall of the upper receiver <NUM>).

As illustrated in <FIG>, <FIG>, and <FIG> showing cross-sectional views at different locations along a length of the upper receiver <NUM>), the cam race <NUM> is secured within a groove <NUM> (shown in <FIG>) within the interior sidewall of the upper receiver <NUM>. The rear face of the cam race <NUM> contacts an interior surface of the groove <NUM>. Moreover, to ensure the cam race <NUM> is positioned appropriately within the groove <NUM>, the height and length of the groove <NUM> are sized slightly larger than the cam race <NUM> to enable the cam race <NUM> to slide into the groove <NUM> without resistance. In other embodiments, the height and length of the groove <NUM> are sized to provide a friction fit between the sidewalls of the groove <NUM> and sidewalls of the cam race <NUM>.

The cam race <NUM> is secured to the upper receiver <NUM> via one or more fasteners. The fasteners may be integrally formed with the cam race <NUM>, such as fastener pins <NUM> extending away from the rear face of the cam race <NUM> as shown in <FIG>. The fastener pins <NUM> extend from a pin base (where the fastener pin is formed with the rear face of the cam race <NUM>) to a distal end. The fastener pins <NUM> are at least substantially linear between the pin base and the distal end prior to installation, as shown in <FIG>. In the illustrated embodiment, the fastener pins <NUM> have a circular cross-section (such that the fastener pins <NUM> define a cylindrical shape), however it should be understood that other cross-sectional shapes (e.g., rectangular, square, oval, triangular, and/or the like) maybe utilized in certain embodiments. In the illustrated embodiment, the fastener pins <NUM> extend through corresponding rivet through-holes <NUM> extending through the sidewall of the upper receiver <NUM> (from the interior surface through an exterior surface of the upper receiver <NUM>). The rivet through-holes <NUM> have a cross-sectional shape corresponding to the cross-sectional shape of the fastener pins <NUM>. The rivet through-holes <NUM> are sized to accommodate the fastener pins <NUM> (having a diameter slightly larger than the diameter of the fastener pins <NUM> to enable the fastener pins <NUM> to slide into corresponding rivet through-holes <NUM>). In some embodiments, the rivet through-holes <NUM> have a diameter (or cross-sectional size) to provide a friction fit with the corresponding fastener pins <NUM>.

With the cam race <NUM> positioned within the groove <NUM> and the fastener pins <NUM> extending through corresponding rivet through-holes <NUM>, distal ends of the fastener pins <NUM> are compressed to deform those distal ends of the fastener pins <NUM> to form expanded portions <NUM> (as shown in <FIG>, which illustrates an example shape of the fastener pins <NUM> after installation into an upper receiver <NUM> having rivet through-holes <NUM> with countersink surrounding an exterior end of the through-holes <NUM>)-such that the distal ends of the fastener pins <NUM> are enlarged to a diameter larger than the diameter of the rivet through-holes <NUM>, thereby securing the cam race <NUM> onto the upper receiver <NUM>. As reflected in the embodiments of <FIG>, the distal ends of the rivets may have an at least substantially flat exterior that is at least substantially flush with the exterior surface of the upper receiver <NUM> (with the enlarged diameter of the distal end fitting within a countersink surrounding the exterior surface end of the through hole <NUM>) or the distal ends of the rivets may protrude beyond the exterior surface of the upper receiver <NUM> (e.g., in a dome shape, a cone shape, or another three-dimensional shape extending beyond the exterior surface of the upper receiver).

In the illustrated embodiments of <FIG>, the exterior surface of the upper receiver <NUM> defines a raised rail <NUM> that is aligned with the groove <NUM> such that the groove <NUM> at least partially extends into the raised rail <NUM>. The raised rail <NUM> ensures the thickness of the upper receiver <NUM> is adequate to support the rivet-based connection between the cam race <NUM> and the upper receiver <NUM>, even with the presence of the groove <NUM> within the interior sidewall of the upper receiver <NUM>. The raised rail <NUM> has a length (measured in the direction of projectile travel) longer than the length of the groove <NUM> and a height taller than the height of the groove <NUM>. The thickness of the raised rail <NUM> (measured between the plane of the surrounding exterior surface of the upper receiver <NUM> and the plane of the outermost surface of the raised rail <NUM>) is sufficient to maintain a secure connection between the upper receiver <NUM> and the cam race <NUM> during the assembly process discussed herein.

As shown in <FIG>, the rivet through-holes <NUM> may be at least substantially linear, having an at least substantially equal diameter along the length of each rivet through hole <NUM>. However, as shown in <FIG> and <FIG>, the rivet through-holes <NUM> may be characterized by a countersink surround an exterior end of each through-hole <NUM>, which may facilitate the formation of a structurally-sound connection between the cam race <NUM> and the upper receiver <NUM>, while maintaining a desired aesthetic appearance (e.g., a planar exterior surface of the raised rail <NUM>) of the upper receiver <NUM>.

As additionally illustrated in the figures, the cam race <NUM> comprises a plurality of fasteners (e.g., a plurality of fastener pins, such as <NUM> fastener pins) along the length of the cam race <NUM> to securely position the cam race <NUM> relative to the upper receiver <NUM>. The fasteners may be evenly spaced along the length of the cam race <NUM>, although other fastener spacing may be provided in certain embodiments. For example, the fasteners may have a keyed spacing, such that the cam race <NUM> can only be inserted in a single orientation (e.g., with an uneven fastener spacing to ensure that the cam race <NUM> only fits into the groove <NUM> when inserted in a desired orientation).

It should be understood that other fastener configurations may be provided for securing the cam race <NUM> into the upper receiver <NUM>. For example, separate rivets may be secured onto both the upper receiver <NUM> and the cam race <NUM>. Screws or other fasteners may be utilized in place of the described rivet configurations. In yet other embodiments, the plurality of fastener pins may extend into corresponding blind rivet holes, having detents, protrusions, or other features within the sidewalls of those blind rivet holes to provide a feature for interacting with an enlarged distal end of the fastener pins to provide a riveted connection between the cam race <NUM> and the upper receiver <NUM>. In yet other embodiments, the fastener configuration may be characterized by different fastener pin <NUM> configurations. For example, a first subset of the plurality of fastener pins <NUM> may extend entirely through corresponding through-holes, such that distal ends of those fastener pins <NUM> may be deformed to form enlarged portions <NUM>. A second subset of the plurality of fastener pins <NUM> may extend partially through corresponding through-holes, or partially into corresponding blind holes, such that the second subset of the plurality of fastener pins <NUM> assist in placement of the cam race <NUM>, but they are not utilized to secure the cam race <NUM> onto the upper receiver <NUM>.

The cam race <NUM> is inserted and secured into the upper receiver <NUM> after the upper receiver <NUM> is formed (e.g., via forging, casting, machining, polishing, surface treatment, and/or the like). The upper receiver <NUM> is formed of a first material, such as an aluminum material.

The upper receiver <NUM> is formed with the raised rail <NUM> integrally formed therewith. For example, the casting mold utilized for forming the upper receiver <NUM> includes a feature corresponding with and configured for forming the raised rail <NUM> on the outer surface of the upper receiver <NUM>. Moreover, the upper receiver <NUM> is additionally formed with the groove <NUM> formed within an interior wall of the upper receiver <NUM> and the rivet through-holes <NUM>. The groove <NUM> and/or the rivet through-holes <NUM> may be cast and/or machined from the upper receiver <NUM>. In certain embodiments, the rivet through-holes <NUM> are formed with a countersink portion at an exterior end thereof. As discussed herein, the countersink portion accepts a portion of the deformed distal end of the fastener pins <NUM> to minimize the amount of material that extends beyond the exterior surface of the raised rail <NUM> from the fastener pins <NUM>.

The cam race <NUM> is formed of a second material, such as a hardened steel material as discussed above. The cam race <NUM> is finished via polishing, coating, surface treatment, and/or the like to provide a desired final finish to the cam race <NUM>. As mentioned, the body <NUM> and the fastener pins <NUM> are integrally formed (to form a single continuous piece of material). It should be understood that the cam pins <NUM> may be modified to accommodate a desired fastener type for a particular embodiment and/or replaced with a different fastener type, as required by the particular embodiment.

Once the upper receiver <NUM> is formed and the cam race <NUM> is formed, the cam race <NUM> is inserted into the groove <NUM> of the upper receiver <NUM>, such that the fastener pins <NUM> extend through corresponding rivet through-holes <NUM> of the upper receiver <NUM>. The upper receiver <NUM> is then placed onto a support rod - such that the support rod extends through the entire interior length of the upper receiver <NUM> (through a front and rear opening of the upper receiver <NUM>). The support rod has a surface that at least substantially matches the surface contour of the slide face of the cam race <NUM>. For example, the support rod may have an at least substantially planar surface. The support rod is placed such that the surface of the support rod is in contact with the cam race <NUM> while the support rod is threaded through the upper receiver <NUM>. In certain embodiments, the support rod had a high rigidity to mitigate bending while subject to the high pressures necessary to deform the distal ends of the fastener pins <NUM> to secure the fastener pins <NUM> within their corresponding rivet through-holes <NUM>.

Once the upper receiver <NUM> is placed on the support rod, a press contacts the distal ends of each of the fastener pins, and a high force is applied to the distal ends of each of the fastener pins (simultaneously or consecutively) to deform the distal ends of the fastener pins-thereby increasing the diameter of the distal ends of the fastener pins to a diameter larger than the diameter of the rivet through-holes <NUM>, thereby locking the cam race <NUM> into the groove <NUM> of the upper receiver <NUM>. The fastener pins <NUM> are effectively crushed between the support rod and the press. Because each of the components (the body <NUM> and the length of each of the fastener pins <NUM> with the exception of a short length adjacent the distal ends) are fit into a corresponding groove <NUM> or rivet through-hole <NUM> with the exception of the distal ends of the fastener pins <NUM>, only the distal ends of the fastener pins <NUM> deform, such that the fastener pins <NUM> form an at least substantially "mushroom" shape, such that the enlarged-diameter distal ends of the fastener pins <NUM> cannot pass through the corresponding rivet through-holes <NUM> having a diameter smaller than the crushed distal ends of the fastener pins <NUM> as reflected within the cross-sectional view of <FIG>.

Although not required, the distal ends of the fastener pins <NUM> may be machined to provide a desired aesthetic to the firearm. The distal ends of the fastener pins <NUM> may be smoothed relative to the surface of the raised rail <NUM> to provide an at least substantially planar surface of the raised rail. In such an embodiment, the material of the distal ends of the fastener pins <NUM> located within the countersink surrounding the rivet through-holes remains sufficiently secure to maintain connection between the cam race <NUM> and the upper receiver <NUM>, even with the removal of excess material extending beyond the outermost surface of the raised rail <NUM>. In other embodiments, the distal ends of the fastener pins <NUM> may be shaped (e.g., into a dome shape, a pyramid shape, or any other shape, if not already provided for during the pressing process discussed above).

The remainder of the firearm is assembled according to assembly methodologies appropriate to the particular firearm, such that a cam pin <NUM> is placed into contact with the slide face of the cam race <NUM>.

Claim 1:
An upper receiver assembly for a firearm, the upper receiver assembly comprising:
an upper receiver (<NUM>) defining a groove (<NUM>) within an interior sidewall, wherein the groove (<NUM>) defines a plurality of through-holes extending through the interior sidewall of the upper receiver (<NUM>) to an exterior sidewall of the upper receiver (<NUM>), wherein the exterior sidewall defines a raised rail (<NUM>) aligned with the groove (<NUM>), such that the groove (<NUM>) at least partially extends into the raised rail (<NUM>); and
a cam race (<NUM>) comprising:
a body (<NUM>) defining a slide face and an opposite rear face, wherein the body (<NUM>) is positioned within the groove (<NUM>); and
a plurality of fastener pins (<NUM>) extending away from the opposite rear face, wherein each of the plurality of fastener pins (<NUM>) extend through a corresponding through-hole.