APPARATUS AND METHODS FOR A BOLT CARRIER ASSEMBLY FOR DIRECT GAS OPERATED FIREARMS

Abstract

An apparatus and methods are provided for a bolt carrier that optimizes the operation of direct gas operated firearms. The bolt carrier is a cylindrical member that reciprocates longitudinally within an upper receiver of the firearm. A distal end of the bolt carrier supports a bolt while a proximal end moves within a receiver extension. The proximal end includes a boss, flutes, and a beveled ring. The boss and the beveled ring are configured to reduce the tilt of the bolt carrier when in a battery position. Different diameters of the boss and the beveled ring cause the bolt carrier to seat advantageously in various positions within the receiver extension. The flutes allow air transfer into and out of the space between the proximal end and the receiver extension to prevent air pressure from hindering the reciprocating motion of the bolt carrier.

Description

PRIORITY

This application claims the benefit of and priority to U.S. Provisional Application, entitled “Apparatus and Methods for a Bolt Carrier Assembly for Direct Gas Operated Firearms,” filed on Jan. 15, 2025, and having application Ser. No. 63/745,674, the entirety of said application being incorporated herein by reference.

FIELD

Embodiments of the present disclosure generally relate to firearms. More specifically, embodiments of the disclosure relate to an apparatus and methods for a bolt carrier for optimizing the operation of a direct gas operated firearm.

BACKGROUND

The AR15/M4/M16 family of firearms and their derivatives, including all direct gas operated versions, have been in use by the military and civilian population for many years. An essential component of direct gas operated firearms is the bolt carrier group. Typically, the bolt carrier group includes a bolt mounted in a bolt carrier that is configured for axial sliding movement and rotation within a firearm. A firing pin slidably mounted within the bolt and bolt carrier restricts reciprocating axial movement of the bolt carrier group. The bolt carrier group further includes a cam-pin that limits rotation between the bolt and the bolt carrier.

The bolt carrier group generally is configured for stripping or picking up ammunition cartridges from a magazine and moving the cartridges into a battery position within a breech of the firearm. After firing each round, the bolt carrier group extracts and ejects the ammunition cartridge through an ejection port on the side of the firearm. The energy to perform these functions is provided by way of hot, expanding gases from the fired cartridge that are directed through a port at the end of the barrel and channeled back to the bolt carrier group. The expanding gases strike, or impinge, the bolt carrier moving it rearward toward the buttstock and into a retracted position. The exhaust gases are then discharged through the ejection port on the side of the firearm. After discharge, a spring acting on the bolt carrier group moves the bolt carrier back to an engaged position while at the same time stripping another cartridge from the magazine and moving that cartridge into the battery position.

Given the popularity of the AR15/M4/M16 family of firearms and their derivatives, there is a continuing desire to improve and simplify the operation of such direct gas operated firearms. Embodiments presented herein provide a bolt carrier for optimizing various aspects and increasing the longevity of a direct gas operated rifle.

SUMMARY

An apparatus and methods are provided for a bolt carrier that optimizes the operation of direct gas operated firearms. The bolt carrier is a cylindrical member that reciprocates longitudinally within an upper receiver of the firearm. A distal end of the bolt carrier supports a bolt while a proximal end moves within a receiver extension. The proximal end includes a boss, flutes, and a beveled ring. The boss and the beveled ring are configured to reduce the tilt of the bolt carrier when in a battery position. Different diameters of the boss and the beveled ring cause the bolt carrier to seat advantageously in various positions within the receiver extension. The flutes allow air transfer into and out of the space between the proximal end and the receiver extension to prevent air pressure from hindering the reciprocating motion of the bolt carrier.

In an exemplary embodiment, a bolt carrier for a direct gas operated firearm comprises: a cylindrical member for moving longitudinally within an upper receiver of the firearm; a distal end for supporting a bolt; a proximal end for moving within a receiver extension; and a forward-biased dwell weight within the proximal end.

In another exemplary embodiment, the proximal end includes a boss, flutes, and a beveled ring. In another exemplary embodiment, the boss and the beveled ring are configured to reduce an allowable pitch of the bolt carrier when in a battery position. In another exemplary embodiment, the bolt carrier, the boss, and the beveled ring have different diameters that cause the bolt carrier to seat advantageously in various positions within the receiver extension. In another exemplary embodiment, the boss provides a relatively tight fit between the proximal end of the bolt carrier and an inner diameter of the receiver extension that reduces tilt of the bolt carrier when in the battery position. In another exemplary embodiment, the flutes are configured to allow air transfer into and out of the space between the proximal end and the receiver extension to prevent air pressure from hindering the reciprocating motion of the bolt carrier.

In another exemplary embodiment, the forward-biased dwell weight is configured to increase inertia of the bolt carrier in the battery position. In another exemplary embodiment, the forward-biased dwell weight is configured to add dwell before the bolt carrier begins to move forward or rearward. In another exemplary embodiment, the forward-biased dwell weight is configured to increase the rebound time of the bolt carrier group between recoil and counter-recoil cycles.

In another exemplary embodiment, the forward-biased dwell weight comprises a sealed cylinder with a spring and a threaded plug. In another exemplary embodiment, the cylinder is configured to slide within a cylindrical interior of the bolt carrier. In another exemplary embodiment, cylindrical guides are incorporated into opposite ends of the cylinder and are configured to slidably contact the interior of the bolt carrier. In another exemplary embodiment, the spring is disposed between the threaded plug and a central hole disposed in the cylinder. In another exemplary embodiment, the threaded plug is a generally disc-shaped member having a diameter and peripheral threads suitable for engaging with threads comprising a threaded portion of the interior of the bolt carrier. In another exemplary embodiment, the threaded plug includes a through hole that can be aligned with holes disposed in the threaded portion of the bolt carrier. In another exemplary embodiment, a pin may be pressed through the holes and across the threaded plug to prevent the threaded plug from loosening within the threaded portion over time.

In another exemplary embodiment, the bolt carrier includes a multiplicity of forward assist notches configured to operate with a forward assist comprising the firearm. In another exemplary embodiment, the bolt carrier includes a cam pin locking path that is configured to reduce stresses on lugs comprising the bolt. In another exemplary embodiment, the cam pin locking path is derived by way of a cycloid-derived unlocking curve.

In an exemplary embodiment, a method for a bolt carrier for a direct gas operated firearm comprises: configuring a cylindrical member for moving longitudinally within an upper receiver of the firearm; configuring a distal end for supporting a bolt; adapting a proximal end for moving within a receiver extension; and incorporating a forward-biased dwell weight within the proximal end.

In another exemplary embodiment, adapting the proximal end includes forming a boss, flutes, and a beveled ring on the proximal end. In another exemplary embodiment, forming the boss and forming the beveled ring include configuring the boss and configuring the beveled ring to reduce an allowable pitch of the bolt carrier when in a battery position. In another exemplary embodiment, adapting the proximal end includes forming different diameters of the bolt carrier, the boss, and the beveled ring to cause the bolt carrier to seat advantageously in various positions within the receiver extension. In another exemplary embodiment, forming the boss includes providing a relatively tight fit between the proximal end of the bolt carrier and an inner diameter of the receiver extension that reduces tilt of the bolt carrier when in the battery position. In another exemplary embodiment, forming the flutes includes configuring the flutes to allow air transfer into and out of the space between the proximal end and the receiver extension to prevent air pressure from hindering the reciprocating motion of the bolt carrier.

In another exemplary embodiment, incorporating the forward-biased dwell weight includes configuring the forward-biased dwell weight to increase inertia of the bolt carrier in the battery position. In another exemplary embodiment, incorporating the forward-biased dwell weight includes configuring the forward-biased dwell weight to add dwell before the bolt carrier begins to move forward or rearward. In another exemplary embodiment, incorporating the forward-biased dwell weight includes configuring the forward-biased dwell weight to increase the rebound time of the bolt carrier group between recoil and counter-recoil cycles.

In another exemplary embodiment, incorporating the forward-biased dwell weight comprises configuring a cylinder to slide within a cylindrical interior of the bolt carrier. In another exemplary embodiment, configuring the cylinder includes configuring cylindrical guides on opposite ends of the cylinder to slidably contact the interior of the bolt carrier. In another exemplary embodiment, incorporating the forward-biased dwell weight comprises disposing a spring between a threaded plug and a central hole comprising the cylinder. In another exemplary embodiment, incorporating the forward-biased dwell weight comprises configuring the threaded plug as a generally disc-shaped member having a diameter and peripheral threads suitable for engaging with threads comprising a threaded portion of the interior of the bolt carrier. In another exemplary embodiment, configuring the threaded plug includes forming a through hole that can be aligned with holes disposed in the threaded portion of the bolt carrier. In another exemplary embodiment, forming the through hole includes forming the through hole to receive a pin pressed through the holes and across the threaded plug to prevent the threaded plug from loosening within the threaded portion over time.

In another exemplary embodiment, configuring the cylindrical member includes configuring a multiplicity of forward assist notches to operate with a forward assist comprising the firearm. In another exemplary embodiment, configuring the cylindrical member includes configuring a cam pin locking path to reduce stresses on lugs comprising the bolt. In another exemplary embodiment, configuring the cam pin locking path includes deriving the cam pin locking path by way of a cycloid-derived unlocking curve.

These and other features of the concepts provided herein may be better understood with reference to the drawings, description, and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings refer to embodiments of the present disclosure in which:

FIG. 1 illustrates a right-side elevation view of an exemplary embodiment of a firearm that utilizes direct gas impingement to operate a bolt carrier group comprising the firearm, in accordance with the present disclosure;

FIG. 2 illustrates a left-hand side view of a bolt carrier in accordance with the present disclosure;

FIG. 3 illustrates an exploded view of an exemplary embodiment of a forward-biased dwell weight comprising a bolt carrier, according to the present disclosure;

FIG. 4 illustrates a close-up view a proximal end of the bolt carrier of FIG. 2, according to the present disclosure;

FIG. 5 illustrates a cross-sectional view of the bolt carrier of FIG. 4, taken along a line 5-5, according to the present disclosure;

FIG. 6 illustrates a right-hand side view of a bolt carrier in accordance with the present disclosure; and

FIG. 7 illustrates a top view of a distal end of the bolt carrier of FIG. 2, showing a cam pin locking path, in accordance with the present disclosure.

While the present disclosure is subject to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. The present disclosure should be understood to not be limited to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent, however, to one of ordinary skill in the art that the bolt carrier and methods disclosed herein may be practiced without these specific details. In other instances, specific numeric references such as “first screw,” may be made. However, the specific numeric reference should not be interpreted as a literal sequential order but rather interpreted that the “first screw” is different than a “second screw.” Thus, the specific details set forth are merely exemplary. The specific details may be varied from and still be contemplated to be within the spirit and scope of the present disclosure. The term “coupled” is defined as meaning connected either directly to the component or indirectly to the component through another component. Further, as used herein, the terms “about,” “approximately,” or “substantially” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein.

The AR15/M4/M16 family of firearms and their derivatives, including all direct gas operated versions, have been in use by the military and civilian population for many years. Given the popularity of the AR15/M4/M16 family of firearms and their derivatives, there is a continuing desire to improve and simplify the operation of such firearms. Embodiments presented herein provide a bolt carrier that optimizes various aspects and increases the longevity of a direct gas operated rifle.

FIG. 1 illustrates a right-side elevation view of an exemplary embodiment of a firearm 100 that utilizes direct gas impingement to cycle the action of a bolt carrier group comprising the firearm, as described herein. In general, the firearm 100 comprises a member of the AR15/M4/M16 family of firearms, and thus the firearm 100 includes an upper receiver 104 that houses the bolt carrier group (not shown) and a lower receiver 108 that receives a magazine 112 containing a multiplicity of ammunition cartridges. The lower receiver 108 positions the ammunition cartridges within the upper receiver 104 such that the bolt carrier group may strip cartridges into a battery position within a breech of a barrel 116. An ejection port 120 on a side of the upper receiver 104 enables the bolt carrier group to eject spent ammunition cartridges after each round is fired. A receiver extension 124 coupled with a rear of the upper receiver 104 provides a housing for longitudinal movement of the bolt carrier group during stripping and ejecting ammunition cartridges. A buttstock 128, handguards 132, and a grip 136 facilitate a practitioner holding and supporting the firearm 100 during operating the firearm 100 by way of a trigger 140. Further, a suppressor (not shown) may be coupled with a muzzle end of the barrel 116 to reduce noise and muzzle flash during operating the firearm 100.

As described herein, the bolt carrier group moves longitudinally within the upper receiver 104 during stripping ammunition cartridges from the magazine 112, chambering the cartridges in the breech, and ejecting spent cartridges. The energy to perform these functions is provided by way of hot, expanding gases from each fired cartridge that cause the bolt carrier to move rearward within the receiver extension 124 toward the buttstock 128. The expanding gases are directed to the bolt carrier group from a port at an end of the barrel 116 by way of a gas block 148 and a gas tube (not shown) disposed within the handguards 132. The expanding gases cause the bolt carrier group to move rearward within the receiver extension 124 and then are discharged through the ejection port 120. After discharge, a spring acting on the bolt carrier group moves the bolt carrier forward to an engaged position while at the same time stripping another ammunition cartridge from the magazine 112 and moving that cartridge into the battery position.

FIG. 2 illustrates an exemplary embodiment of bolt carrier 144 that is configured to move longitudinally within the upper receiver 104 during stripping ammunition cartridges from the magazine 112, chambering the cartridges in the breech, and ejecting spent cartridges. The bolt carrier is a generally cylindrical member supporting a bolt 150 at a distal end 152 and having a boss 154, flutes 158, and a beveled ring 162 disposed at a proximal end 156. The boss 154 and the beveled ring 162 are configured to reduce an allowable pitch of the bolt carrier 144 when in a battery position. The bolt carrier 144, the boss 154, and the ring 162 have different diameters that cooperate to cause the bolt carrier 144 to seat advantageously in various positions within the receiver extension 124 (see FIG. 1). Further, the boss 154 provides a tighter fit between the proximal end 156 of the bolt carrier 144 and an inner diameter of the receiver extension 124 that reduces tilt of the bolt carrier 144 when in the battery position. The flutes 158 are configured to allow air transfer into and out of the space between the proximal end 156 and the receiver extension 124 to prevent air pressure from hindering the reciprocating motion of the bolt carrier 144.

FIG. 3 illustrates an exploded view of an exemplary embodiment of a forward-biased dwell weight 160 that may be incorporated into the bolt carrier 144, according to the present disclosure. The forward-biased dwell weight 160 is configured to provide a more efficient use of kinetic energy in the bolt carrier 144 for reliable cartridge extraction without increasing peak carrier group velocity. As will be appreciated, during the powering cycle, work is performed by expanding gas to accelerate the bolt carrier 144. As the bolt carrier 144 accelerates, both the bolt carrier 144 and the forward-biased dwell weight 160 accumulate kinetic energy. After the powering cycle is complete (i.e., no more meaningful gas work is being performed), the bolt carrier 144 and forward-biased dwell weight 160 both have achieved peak velocity and rearward momentum. At this point, the extraction cycle begins. The bolt carrier 144 begins to lose kinetic energy due to frictional losses from cartridge extraction as well as spring force resistance from the recoil spring and hammer spring. The forward-biased dwell weight 160 continues rearward, unimpeded by these forces, and begins to transfer some of its kinetic energy back to the bolt carrier 144 through the spring 168 (see FIG. 3) and/or directly to the bolt carrier 144 upon impact with the threaded plug 172 at the proximal end 156 of the bolt carrier 144. Thus, the forward-biased dwell weight 160 prolongs overall cycle time (i.e., adds “dwell”), which benefits reliability in reducing mechanical wear and providing ample time for the magazine 112 to present the next cartridge for feeding even in adverse environmental conditions.

As shown in FIG. 3, the forward-biased dwell weight 160 comprises a sealed cylinder 164 with a spring 168 and a threaded plug 172. The cylinder 164 is configured to slide within a cylindrical interior 180 of the bolt carrier 144. The mass of the cylinder 164 provides the inertia effect mentioned above. Further, cylindrical guides 184 are incorporated into opposite ends of the cylinder 164 and are configured to slidably contact the interior 180 of the bolt carrier 144. The cylindrical guides 184 may have a slightly larger diameter than the rest of the cylinder 164 such that only the cylindrical guides 184 contact the interior 180 of the bolt carrier 144. Thus, the cylinder 164 is configured to move forward and rearward within the bolt carrier 144 with minimal friction.

The spring 168 is disposed between the threaded plug 172 and a central hole 188 disposed in the cylinder 164. As will be appreciated, the spring 168 biases the cylinder 164 in a forward disposition within the interior 180 of the bolt carrier 144. In the illustrated embodiment, the forward disposition gives rise to a separation distance (not shown) between the cylinder 164 and the threaded plug 172. The separation distance is proportional to an increase in rebound time (i.e., “rear dwell”) imparted to the bolt carrier 144. As such, the separation distance, as well as the mass of the cylinder 164 and the spring force of the spring 168, may be tuned to produce a desired dwell of the bolt carrier 144. Further, the central hole 188 includes a narrow portion (not shown) configured to allow airflow in and out of the space between the cylinder 164 and the threaded plug 172. As such, the narrow portion of the central hole 188 prevents air pressure between the cylinder 164 and the threaded plug 172 from hindering the longitudinal movement of the cylinder 164.

With continuing reference to FIG. 3, the threaded plug 172 is a generally disc-shaped member having a diameter and peripheral threads 200 suitable for engaging with threads comprising a threaded portion 204 of the interior 180 of the bolt carrier 144. The threaded plug 172 includes a shaped opening 208 configured to receive a suitable tool for driving the threaded plug 172 into the threaded portion 204. The threaded plug 172 further includes a through hole 212 that can be aligned with holes 216 disposed in the threaded portion 204 of the bolt carrier 144. Thus, when the threaded plug 172 is advantageously engaged with the threaded portion 204, such that the through hole 212 aligns with the holes 216, a pin 176 may be pressed through the holes 216 and across the threaded plug 172. As such, the pin 176 serves to prevent the threaded plug 172 from loosening within the threaded portion 204 over time.

As mentioned hereinabove, the forward-biased dwell weight 160 provides an inertial effect when the bolt carrier 144 bottoms out at the end of its stroke, at which point the cylinder 164 continues on and thus introduces a pause before the bolt carrier 144 begins to move forward again. In some embodiments, the forward-biased dwell weight 160 may slow down the very first part of unlocking the bolt 150, which has been observed to be beneficial, in some embodiments. Further, the forward-biased dwell weight 160 is configured to prevent the bolt carrier 144 from bottoming out on a barrel extension comprising the firearm 100 during forward movement. In some embodiments, an elastomer may be disposed on a front surface of cylinder 164 to prolong momentum transfer between the forward-biased dwell weight 160 and the bolt carrier 144, thereby staggering total momentum transfer between bolt carrier 144 and the barrel extension and reducing overall restitution of the bolt carrier group upon impact with the barrel extension, commonly known as “bolt bounce.”

FIG. 4 illustrates a close-up view the proximal end 156 of the bolt carrier 144, according to the present disclosure. As described hereinabove, the proximal end 156 includes a boss 154, flutes 158, and a beveled ring 162. The boss 154 and the beveled ring 162 are configured to reduce an allowable pitch of the bolt carrier 144 when in a battery position. As best shown in FIG. 5, the bolt carrier 144 and the boss 154 have different diameters. The diameter of the boss 154 is configured to cause the bolt carrier 144 to seat advantageously in various positions within the receiver extension 124 (see FIG. 1). More specifically, the boss 154 provides a relatively low clearance fit between the proximal end 156 of the bolt carrier 144 and an inner diameter of the receiver extension 124. The low clearance fit reduces the tilt of the bolt carrier 144 when in the battery position. The flutes 158 are configured to allow air transfer into and out of the space between proximal end 156 and the receiver extension 124 to prevent air pressure from hindering the reciprocating motion of the bolt carrier 144.

FIG. 6 illustrates a right-hand side view of the bolt carrier 144. The illustrated embodiment of bolt carrier 144 is configured to operate with a forward assist 224 comprising the firearm 100 shown in FIG. 1. The illustrated embodiment of the forward assist 224 is positioned farther forward along the firearm 100 than the forward assists of conventional firearms. The forward position of the forward assist 224 is configured to optimize the ergonomics of the firearm 100. As will be appreciated by those skilled in the art, the position of the forward assist 224 reduces the number of forward assist notches 228 that must be machined into the bolt carrier 144, as shown in FIG. 6.

FIG. 7 illustrates an exemplary embodiment of a cam pin locking path 232. The cam pin locking path 232 is configured to reduce stresses on lugs 236 comprising the bolt 150 by improving the unlocking cam path as compared with conventional firearms. The cam pin locking path 232 is derived by way of a cycloid-derived unlocking path (e.g., a “curve”) instead of a helical-derived path or a polynomial-derived path typically used in conventional firearms. Analysis has demonstrated that a cycloid unlocking path provides about a 50% decrease in peak rotational acceleration of the bolt 150 as compared to a polynomial-derived path that drives the cam path in conventional firearms. Thus, the cycloid unlocking path increases continuity of cam pin to cam path contact, thereby reducing contact stress of the interaction and reducing peak bending loads on the bolt locking lugs due to frictional forces resisting bolt 150 rotation.

Methods of the present disclosure may include configuring a cylindrical member for moving longitudinally within an upper receiver 104 of the firearm 100, configuring a distal end 152 for supporting a bolt 150, and adapting a proximal end 156 for moving within a receiver extension 124 of the firearm 100. The methods may further include incorporating a forward-biased dwell weight 160 within the proximal end 156. Incorporating the forward-biased dwell weight 160 can include configuring the forward-biased dwell weight 160 to increase inertia of the bolt carrier 144 in the battery position. In some embodiments, incorporating the forward-biased dwell weight 160 may include configuring the forward-biased dwell weight 160 to add dwell before the bolt carrier 144 begins to move forward or rearward. In some embodiments, incorporating the forward-biased dwell weight 160 may further include configuring the forward-biased dwell weight 160 to prevent the bolt carrier 144 from bottoming out on a barrel extension comprising the firearm 100 during forward movement.

Moreover, in some embodiments, incorporating the forward-biased dwell weight 160 may comprise configuring a cylinder 164 to slide within a cylindrical interior 180 of the bolt carrier 144. Configuring the cylinder 164 may include, in some embodiments, configuring cylindrical guides 184 on opposite ends of the cylinder 164 to slidably contact the interior 180 of the bolt carrier 144. In some embodiments, incorporating the forward-biased dwell weight 160 may comprise disposing a spring 168 between a threaded plug 172 and a central hole 188 comprising the cylinder 164. Further, in some embodiments, incorporating the forward-biased dwell weight 160 may comprise configuring the threaded plug 172 as a generally disc-shaped member having a diameter and peripheral threads 200 suitable for engaging with threads comprising a threaded portion 204 of the interior 180 of the bolt carrier 144. Configuring the threaded plug 172 may include, in some embodiments, forming a through hole 212 that can be aligned with holes 216 disposed in the threaded portion 204 of the bolt carrier 144. Forming the through hole 212 may include, in some embodiments, forming the through hole 212 to receive a pin 176 pressed through the holes 216 and across the threaded plug 172 to prevent the threaded plug 172 from loosening within the threaded portion 204 over time.

In some embodiments, adapting the proximal end 156 may include forming a boss 154, flutes 158, and a beveled ring 162 on the proximal end 156. In some embodiments, forming the boss 154 and forming the beveled ring 162 may include configuring the boss 154 and configuring the beveled ring 162 to reduce an allowable pitch of the bolt carrier 144 when in a battery position. In some embodiments, adapting the proximal end 156 may further include forming different diameters of the bolt carrier 144, the boss 154, and the beveled ring 162 to cause the bolt carrier 144 to seat advantageously in various positions within the receiver extension 124. Moreover, in some embodiments, forming the boss 154 may include providing a relatively tight fit between the proximal end 156 of the bolt carrier 144 and an inner diameter of the receiver extension 124 that reduces tilt of the bolt carrier 144 when in the battery position. In some embodiments, forming the flutes 158 may include configuring the flutes 158 to allow air transfer into and out of the space between the proximal end 156 and the receiver extension 124 to prevent air pressure from hindering the reciprocating motion of the bolt carrier 144.

In some embodiments, configuring the cylindrical member may include configuring a multiplicity of forward assist notches 228 to operate with a forward assist 224 comprising the firearm 100. Further, in some embodiments, configuring the cylindrical member may include configuring a cam pin locking path 232 to reduce stresses on lugs 236 comprising the bolt 150. Configuring the cam pin locking path 232 may include, in some embodiments, deriving the cam pin locking path 232 by way of a cycloid-derived unlocking curve.

While the bolt carrier and methods have been described in terms of particular variations and illustrative figures, those of ordinary skill in the art will recognize that the bolt carrier is not limited to the variations or figures described. In addition, where methods and steps described above indicate certain events occurring in certain order, those of ordinary skill in the art will recognize that the ordering of certain steps may be modified and that such modifications are in accordance with the variations of the bolt carrier. Additionally, certain of the steps may be performed concurrently in a parallel process, when possible, as well as performed sequentially as described above. To the extent there are variations of the bolt carrier, which are within the spirit of the disclosure or equivalent to the bolt carrier found in the claims, it is the intent that this patent will cover those variations as well. Therefore, the present disclosure is to be understood as not limited by the specific embodiments described herein, but only by scope of the appended claims.

Claims

1. A bolt carrier for a direct gas operated firearm, comprising:

a cylindrical member for moving longitudinally within an upper receiver of the firearm;

a distal end for supporting a bolt;

a proximal end for moving within a receiver extension; and

a forward-biased dwell weight within the proximal end.

2. The bolt carrier of claim 1, wherein the proximal end includes a boss, flutes, and a beveled ring.

3. The bolt carrier of claim 2, wherein the boss and the beveled ring are configured to reduce an allowable pitch of the bolt carrier when in a battery position.

4. The bolt carrier of claim 2, wherein the bolt carrier, the boss, and the beveled ring have different diameters that cause the bolt carrier to seat advantageously in various positions within the receiver extension.

5. The bolt carrier of claim 2, wherein the boss provides a relatively tight fit between the proximal end of the bolt carrier and an inner diameter of the receiver extension that reduces tilt of the bolt carrier when in the battery position.

6. The bolt carrier of claim 2, wherein the flutes are configured to allow air transfer into and out of the space between the proximal end and the receiver extension to prevent air pressure from hindering the reciprocating motion of the bolt carrier.

7. The bolt carrier of claim 1, wherein the forward-biased dwell weight is configured to increase inertia of the bolt carrier in the battery position.

8. The bolt carrier of claim 1, wherein the forward-biased dwell weight is configured to add dwell before the bolt carrier begins to move forward or rearward.

9. The bolt carrier of claim 1, wherein the forward-biased dwell weight is configured to increase the rebound time of the bolt carrier group between recoil and counter-recoil cycles.

10. The bolt carrier of claim 1, wherein the forward-biased dwell weight comprises a sealed cylinder with a spring and a threaded plug.

11. The bolt carrier of claim 10, wherein the cylinder is configured to slide within a cylindrical interior of the bolt carrier.

12. The bolt carrier of claim 11, wherein cylindrical guides are incorporated into opposite ends of the cylinder and are configured to slidably contact the interior of the bolt carrier.

13. The bolt carrier of claim 11, wherein the spring is disposed between the threaded plug and a central hole disposed in the cylinder.

14. The bolt carrier of claim 11, wherein the threaded plug is a generally disc-shaped member having a diameter and peripheral threads suitable for engaging with threads comprising a threaded portion of the interior of the bolt carrier.

15. The bolt carrier of claim 14, wherein the threaded plug includes a through hole that can be aligned with holes disposed in the threaded portion of the bolt carrier.

16. The bolt carrier of claim 15, wherein a pin may be pressed through the holes and across the threaded plug to prevent the threaded plug from loosening within the threaded portion over time.

17. The bolt carrier of claim 1, wherein the bolt carrier includes a multiplicity of forward assist notches configured to operate with a forward assist comprising the firearm.

18. The bolt carrier of claim 1, wherein the bolt carrier includes a cam pin locking path that is configured to reduce stresses on lugs comprising the bolt.

19. The bolt carrier of claim 18, wherein the cam pin locking path is derived by way of a cycloid-derived unlocking curve.