Patent Application
20170160028
The present invention relates to the action of a firearm. In particular, the present invention relates to a buffer assembly used in conjunction with a reciprocating bolt firearm.
Existing reciprocating bolt firearms, including carbines and rifles, such as the AR15/M16 among others, employ a buffer assembly to reduce the effect of recoil on the operator and as part of the firing cycle of the firearm. The buffer assembly typically includes a buffer tube, a buffer spring and a buffer. However, existing buffer assemblies suffer from a number of deficiencies. For example, existing assemblies are heavy, noisy, operate in course or rough manner that distracts the operator, require significant maintenance, and are not easily adjusted to meet individual requirements.
Advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings.
Throughout this application, the directional references, such as forward, rearward, left, right, bottom and top, will be used. These and other such references are relative to the firing direction of the firearm, which fires in a forward direction. Such references are used for ease in describing the present invention and should not be construed as limiting the scope of the invention. As used in the description herein and throughout the claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise: the meaning of “a,” “an,” and “the” includes plural reference, the meaning of “in” includes “in” and “on.” Also, reference designators shown herein in parenthesis indicate components shown in a figure other than the one being discussed.
In existing buffer assemblies, the buffer has mass, the inertia of which must be overcome by the building forces within the operating system of the rifle. This imparts a desired delay in the cycle of the mechanism. The buffer contains weights that can be changed out for more or less desired weight, depending on the mass required for the correct operation of any number of specific weapon configurations. These weights are made from steel rod, with an oxide finish. The steel weights may be separated by rubber disks intended to dampen impact and noise. The steel oxide finish and rubber disks create significant friction and resistance to free motion.
The weights inside the buffer are allowed to move fore and aft approximately 0.080″ to delay the impact force of the buffer body at both extremes of its travel. The purpose of the free weight inside the buffer is to create a “double blow” or a delayed impact to hold the buffer unit stationary for a moment at each end of its travel cycle. This delay is required to allow time for the magazine to present a cartridge into the path of the reciprocating bolt, and at the “battery” position, to hold the bolt closed- to prevent a condition called “bolt bounce” that can halt normal firing function.
The body diameter of the buffer is significantly smaller than the inside dimension of the buffer spring, and the diameter of the spring is significantly smaller than the inside diameter of the receiver extension, to allow for variation in manufacturing and also to facilitate assembly or disassembly. The buffer body is traditionally made from aluminum and anodized.
The disparities in interfacing dimensions create compound coiling as the spring compresses. This action creates excessive noise and friction; as the spring compresses and takes on a secondary spiral it grows and creates a braking force against the walls of the receiver extension. This increasing side load and friction contributes to inconsistent cyclic timing and ultimately sporadic malfunction. Prior buffer assemblies have significant differences between buffer body and spring inside diameter, the spring outside diameter and receiver extension inside diameter, and the buffer “head” outside diameter and receiver extension inside diameter. These differences in these dimensions generally exceed 0.030 inches. These large tolerances contribute to noise, friction, binding, wear, and rough operation.
The buffer head 122, where it contacts the rear face of the bolt carrier 104, is a smooth flat surface. These two parts are allowed to shift out of alignment in any direction; further increasing the potential and frequency that the carrier may rub or contact the inside surface of the receiver extension. As the carrier is allowed to pitch and yaw, increased wear will result inside the upper receiver.
Each of these incidences of friction, and/or misalignment can combine to create a compounded effect that results in a rifle with rough, noisy, and inconsistent and ultimately unreliable operation. This incremental decay of the integrity of the system will lead to poor accuracy, and diminished service life of the firearm. In addition, the spring is considered a wear item that needs routine and regular replacement.
Accordingly, there exists a need for a buffer assembly that is lighter, quieter, smoother, and easier to tune and adjust to meet individual requirements. Advantages of such an improved buffer assembly may include enhanced performance and capability to the shooter. Accuracy, speed, control, and recovery between shots may also be positively affected.
Embodiments of the buffer assembly 200 further comprise a liner 250. The liner 250 may comprise a thermoplastic polymer, for example PET (polyethylene terephthalate) or PETG (PET glycol-modified). Alternatively, the liner 250 may comprise another appropriate material as would be understood by one of ordinary skill in the art, including PTFE (polytetrafluoroethylene), phenolics, nylon, acetal, UHMWPE (ultrahigh-molecular-weight polyethylene) or other materials. In embodiments of the invention it is advantageous to use a material that reduces the friction of the internal components against the interior sidewall 236 of the receiver extension. In some embodiments, the liner may have a thickness of between 0.010 and 0.020 inches and more preferably between 0.015 and 0.018 inches.
The liner 250 may, as shown in
Embodiments of the buffer assembly 200 further comprise a spring 260. In the illustrative embodiment, the spring is a coil spring. The liner 250 is positioned between an interior sidewall of the receiver extension 230 and an outside diameter of the spring 260. Among other advantages, the liner reduces friction between the spring and the receiver extension sidewall. The internal diameter of the liner 250 is very close to the outside diameter of the spring 260. In some embodiments, the difference between outside diameter of the spring and the inside diameter of the liner is 0.030 inches or less across the diameter, and preferably less than 0.010 inches across the diameter.
Embodiments of the buffer assembly may be used in any AR-15 patterned rifle. In carbine applications (short stock), a standard spring intended for the AR-10 carbine may used. In rifle applications (fixed, long stock), an AR-10 rifle spring or an AR-15 rifle spring may be used. The spring rate may be chosen as would be understood by one of ordinary skill in the art. Higher rate springs may have an increase rate of deceleration, which contributes to decreased felt recoil, and a more positive forward stroke of the system.
Embodiments of the buffer assembly 200 also comprise a buffer 300. The buffer is shown in more detail in
The buffer body 320 also includes a generally cylindrical cavity 334 that extends longitudinally into the buffer body from the forward end. The buffer body also includes air passageways 336, 338 extending through the sidewall of the buffer body near the forward and rearward ends. The buffer body 320 may be formed of any appropriate material, but is preferably formed from a polymer, for example a PET.
The buffer head 322 is removably connected to the buffer body 320 to enclose the cavity 334. The buffer head may comprise a bumper 340. The bumper 340 may be connected to the buffer head 322 by pressing a post 342 formed on a forward portion of the bumper into a hole 344 extending through the buffer head. The buffer head main portion 346 may be formed of aluminum, and in particular, a relatively hard aluminum (2xxx or 7xxx series). The bumper 340 may be formed of a polymer. In particular, the bumper 340 may be a relatively hard polymer damper for mitigating impact forces caused by the impact of the buffer weight(s) (discussed below) as the system returns to battery at its forward position.
The buffer head may serve as a bearing surface for the hardened steel bolt carrier (104). The forward surface of the head (that which contacts the carrier) is shaped as a truncated cone 348, sufficient to interact with the bolt carrier on the datum of the cone. Engagement between the bolt carrier and the cone 348 helps ensure proper coaxial and perpendicular alignment of the bolt carrier group and the buffer assembly. This measure ensures the bolt experiences no tilt or pitch, which can contribute to poor function and excessive wear.
This guide ring 328 of the buffer body 320 has larger diameter than the head 322 to prevent the head from contacting the receiver extension sidewall 236. Accordingly, in some embodiments, the polymer guide ring 328 my contact the sidewall 236, but the aluminum buffer head 322 will not.
When the buffer 300 is inserted into the receiver extension 230, the spring 260 surrounds the nose 324 and central portion 326 of the buffer body 320. An end of the spring seats against a shoulder 330 formed between the central portion 326 and guide ring 328 of the buffer body. The outside diameter of the buffer body central section 326 is very close to the inner diameter of the spring 260. In some embodiments, the difference between inside diameter of the spring and the outside diameter of the buffer body is 0.030 inches or less across the diameter, and preferably less than 0.010 inches across the diameter.
The Buffer 300 may also comprise one or more weights 350. The weight 350 is inserted into the cavity 334 of the buffer body 320. In some embodiments, the weight has a generally cylindrical shape that coincides with the shape of the cavity. However, the weight is shorter than the cavity 334 so that the weight 350 can reciprocate within the cavity. The weight may be polished to reduce friction and ease movement within the cavity, particularly if the buffer body is constructed of a polymer material.
The weight 350 may include a single weight or multiple weights in various configurations. The total mass inside the buffer body may be altered by substituting different materials and/or structures. Weight examples include tungsten, steel, or aluminum, formed into bars or pellets or balls, or steel or lead or tungsten granulated media. Other suitable materials include brass, nickel, carbide, copper, zinc, or alloys such as Babbitt or Mallory. Adjusting the buffered mass inside the buffer body may allow a user to fine tune the system's timing and the energy imparted by the buffer to balance recoil forces of the rifle.
As illustrated in
Returning to
The damper post head 416 has a larger diameter than the central portion 412, forming a shoulder 418 where the two sections meet. When the damper assembly 400 and the spring 260 are inserted into the receiver extension 230, the spring 260 surrounds the nose 414 and central portion 412 of the damper post 410. An end of the spring seats against a shoulder 418 formed between the central portion 412 and head 416 of the post. The outside diameter of the damper post central section 412 is very close to the inner diameter of the spring 260. In some embodiments, the difference between inside diameter of the spring and the outside diameter of the damper post is 0.030 inches or less across the diameter, and preferably less than 0.010 inches across the diameter.
Embodiments of the damper post 416 include a cavity 420 or recess formed within the nose portion 414. In the illustrative embodiments, the cavity 420 is centered in the post, generally cylindrically shaped, and extends to a depth that is less than its diameter.
The damper assembly further comprises a damper ball 430. The damper ball may be formed, at least in part, from a fluoropolymer material, for example, Viton® from DuPont, that absorbs and dissipates energy and impact forces. Other materials may be used as would be understood by one of skill in the art. However, it is preferable that the material that reduces return energy and rebound impact forces. A rapid return of energy in the system may negatively attenuate the intended effect of the buffer. The energy absorbing nature of a fluoropolymer material, for example, leaves the buffer spring solely responsible for initiating the return stroke of the system.
The damper ball 430 may be positioned in a cavity 420 formed in a forward end of the damper post 410. The damper ball may be sized such that it is press-fit into and retained by the cavity. Alternatively, the damper ball may be adhered or otherwise fixed to the post. The damper ball is described and illustrated as a ball having a generally spherical shape. However, the damper ball may be of any appropriate shape, including, for example, a cylinder, a hemisphere, a disc, a cube or any other shape that would allow it to extend beyond the end of the damper post 410.
Embodiments of the buffer assembly 1200 comprise a damper assembly 500. The damper assembly 500 is shown in more detail in
The damper assembly 500 further comprises a damper ball 430 as described above. In contrast to the damper post (410) of the rifle configuration, the damper disc 510 does not space the damper ball 430 away from the rear wall of the receiver bore 234. Rather, the damper disc may comprise a cavity 520 formed in the nose portion 514 that extends through a significant portion of the length of the damper disc. In some embodiments, the cavity extends completely through the damper disc such that an opening 522 is formed on the rear side of the damper disc. The damper ball 430 may be positioned in a cavity 520 formed in the damper disc 510.
Illustrative embodiments of the invention show the use of a damper post (410) or a damper disc (510). However, one of skill in the art would understand that the damper post/disc is not limited to the specifically illustrated lengths and that a post/disc of any length in between may be appropriate depending on the length and configuration of the firearm's stock and receiver extension.
The damper disc head 516 has a larger diameter than the central portion 512, forming a shoulder 518 where the two sections meet. When the damper assembly 500 and the spring 260 are inserted into the receiver extension 1230, the spring 260 surrounds the nose 514 and central portion 512 of the damper disc 510. An end of the spring seats against a shoulder 518 formed between the central portion 512 and head 516 of the disc. The outside diameter of the damper disc central section 512 is very close to the inner diameter of the spring 260. In some embodiments, the difference between inside diameter of the spring and the outside diameter of the damper disc is 0.030 inches or less across the diameter, and preferably less than 0.010 inches across the diameter.
| Number | Date | Country | |
|---|---|---|---|
| 62263163 | Dec 2015 | US |
