U.S. patent application number 15/368950 was filed with the patent office on 2017-06-08 for buffer assembly for firearm reciprocating bolt.
The applicant listed for this patent is WIPH, LLC. Invention is credited to David A.T. Lake, Andrew D. Martinez, JR., Michael H. Walther.
Application Number | 20170160028 15/368950 |
Document ID | / |
Family ID | 58798081 |
Filed Date | 2017-06-08 |
United States Patent
Application |
20170160028 |
Kind Code |
A1 |
Martinez, JR.; Andrew D. ;
et al. |
June 8, 2017 |
BUFFER ASSEMBLY FOR FIREARM RECIPROCATING BOLT
Abstract
A buffer assembly for a firearm has a tubular receiver
extension. A damper assembly is positioned within the receiver
extension adjacent the receiver extension rear end, and a spring is
positioned within the receiver extension with the rear end of the
spring surrounding the damper assembly. A buffer is positioned
within the receiver extension at the opposite end of the spring
from the damper assembly. The receiver extension has a liner that
surrounds the spring creating a layer between the spring and the
receiver extension. The liner may be a friction reducing material
such as a polymer material.
Inventors: |
Martinez, JR.; Andrew D.;
(St. George, UT) ; Lake; David A.T.; (Washington,
UT) ; Walther; Michael H.; (St. George, UT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
WIPH, LLC |
St. George |
UT |
US |
|
|
Family ID: |
58798081 |
Appl. No.: |
15/368950 |
Filed: |
December 5, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62263163 |
Dec 4, 2015 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F41A 3/66 20130101; F41A
3/80 20130101 |
International
Class: |
F41A 3/80 20060101
F41A003/80; F41A 3/66 20060101 F41A003/66 |
Claims
1. A buffer assembly for a firearm compromising: a receiver
extension having a tubular shape, the receiver extension comprising
a rear end, an open front end, an inner surface and an outer
surface; a damper assembly positioned within the receiver extension
adjacent the receiver extension rear end; a spring positioned
within the receiver extension, wherein the spring comprises an
outer surface, a front end and a rear end, wherein and the spring
rear end at least partially surrounds the damper assembly; a buffer
positioned within the receiver extension, wherein the buffer
comprises a weight and the spring front end at least partially
surrounds the buffer; a liner at least partially covering the inner
surface of the receiver extension, wherein the liner is positioned
between at least a portion of the spring outer surface and a
portion of the receiver extension inner surface.
2. The buffer assembly of claim 1 wherein the buffer further
comprises a buffer body and a buffer head.
3. The buffer assembly of claim 2 wherein the buffer body comprises
a cavity and the weight is positioned within the buffer body
cavity.
4. The buffer assembly of claim 3 wherein the buffer body cavity
comprises an open end and the buffer head is removably connected to
the buffer body to enclose the cavity.
5. The buffer assembly of claim 2 wherein the buffer body comprises
a polymer material.
6. The buffer assembly of claim 2 wherein the buffer head comprises
aluminum.
7. The buffer assembly of claim 1 wherein the spring comprises a
coil spring having an inside diameter and an outside diameter.
8. The buffer assembly of claim 7 wherein the damper assembly
comprises a damper post.
9. The buffer assembly of claim 8 wherein the damper post comprises
a head section, a central section having an outside diameter and a
nose section.
10. The buffer assembly of claim 9 wherein a difference between the
inside diameter of the spring and the outside diameter of the
damper post central section is 0.030 inches or less across the
diameter.
11. The buffer assembly of claim 9 wherein a difference between the
inside diameter of the spring and the outside diameter of the
damper post central section is less than 0.010 inches across the
diameter.
12. The buffer assembly of claim 1 wherein the damper assembly
comprises a damper ball.
13. The buffer assembly of claim 1 wherein the liner comprises a
thermoplastic polymer.
14. The buffer assembly of claim 1 wherein the liner has a
thickness of between 0.010 and 0.020 inches.
15. The buffer assembly of claim 1 wherein the liner has a
thickness of between 0.015 and 0.018 inches.
16. The buffer assembly of claim 1 wherein the liner comprises a
sheet of material rolled into a tubular shape and inserted into the
receiver extension such that a seam extends longitudinally along a
side of the receiver extension inner surface.
17. The buffer assembly of claim 1 wherein the liner comprises a
tube.
18. The buffer assembly of claim 1 wherein the liner comprises a
material that is sprayed onto the receiver extension inner
surface.
19. The buffer assembly of claim 7 wherein a difference between the
outside diameter of the spring and an inside diameter of the liner
is 0.030 inches or less across the diameter.
20. The buffer assembly of claim 7 wherein a difference between the
outside diameter of the spring and an inside diameter of the liner
is less than 0.010 inches across the diameter.
Description
FIELD OF THE INVENTION
[0001] 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.
BACKGROUND OF THE INVENTION
[0002] 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.
BRIEF DESCRIPTION OF THE FIGURES
[0003] Advantages of the invention will become apparent upon
reading the following detailed description and upon reference to
the drawings.
[0004] FIG. 1 is an exploded isometric view of a buffer assembly in
accordance with existing firearms.
[0005] FIG. 2 is an exploded isometric view of a rifle-length
buffer assembly in accordance with embodiments of the present
invention.
[0006] FIG. 3 is a view of the front end of a buffer assembly in
accordance with the embodiment of FIG. 2.
[0007] FIG. 4 is a cross sectional view of a buffer assembly as
seen at section A-A of FIG. 3.
[0008] FIGS. 5-10 are front end and cross sectional views of the
buffer assembly of FIGS. 3-4 as seen at various times during the
buffer retraction cycle.
[0009] FIGS. 11-15 are various side and end views of a buffer in
accordance with embodiments of the present invention.
[0010] FIGS. 16-17 are isometric views of a buffer in accordance
with the embodiment of FIGS. 11-15.
[0011] FIG. 18 is an exploded isometric view of a buffer in
accordance with the embodiment of FIGS. 11-15.
[0012] FIGS. 19-22 various side and end views of a damper post in
accordance with embodiments of the present invention.
[0013] FIGS. 23-24 are isometric views of a damper post in
accordance with the embodiment of FIGS. 19-22.
[0014] FIG. 25 is an exploded isometric view of a damper post in
accordance with the embodiment of FIGS. 19-22.
[0015] FIG. 26 is an exploded isometric view of a carbine-length
buffer assembly in accordance with embodiments of the present
invention.
[0016] FIG. 27 is a view of the front end of a buffer assembly in
accordance with the embodiment of FIG. 26.
[0017] FIG. 28 is a cross sectional view of a buffer assembly as
seen at section B-B of FIG. 27.
[0018] FIGS. 29-34 are front end and cross sectional views of the
buffer assembly of FIGS. 3-4 as seen at various times during the
buffer retraction cycle.
[0019] FIG. 35 is an exploded isometric view of a damper disc in
accordance with embodiments of the present invention.
[0020] FIGS. 36-37 are isometric views of a damper disc in
accordance with the embodiment of FIG. 35.
[0021] FIGS. 38-40 are various side and end views of a damper post
in accordance with the embodiment of FIG. 35.
[0022] FIG. 41 is an isometric view of a buffer assembly in
accordance with embodiments of the present invention as positioned
in connection with a lower receiver.
DETAILED DESCRIPTION
[0023] 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.
[0024] FIG. 1 shows an embodiment a prior art carbine buffer
assembly used with the AR15/M16 family of firearms. The buffer
assembly 100 includes a carbine length buffer tube (also known as a
receiver extension) 130, spring 140, bolt carrier 104, bolt 106 and
buffer 120. The rear end of the bolt carrier 310 abuts the front of
the buffer 320 when the host rifle is fully assembled. The buffer
120 is contained within the buffer tube 130 and the bolt carrier
104 within an upper receiver when in battery. While the carbine
buffer tube 130 does not receive the entire length of the bolt
carrier 104 during its reciprocating motion, the length of the
buffer tube is required to facilitate sufficient rearward movement
of the bolt carrier 104 and compression of the spring 140 for
proper function of the firearm. The spring 140 and buffer 120 are
required to provide a surface and force that resists the rearward
movement of the bolt carrier 104. The weight of the buffer 120
maybe selected to minimize bolt bounce and assist in the proper
operation of a gas operating system.
[0025] 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.
[0026] 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.
[0027] 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.
[0028] 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.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] FIGS. 2-4 shows a buffer assembly 200 in accordance with
embodiments of the present invention. The buffer assembly 200
includes a receiver extension 230 (also referred to as a buffer
tube). The receiver extension 230 is generally tubular in shape
with a rear end 232 and an open front end 234. The rear end 232 may
include a reduced diameter such that a shoulder 233 is formed or
may be closed. The front end may include a threaded outside
diameter 235 that is adapted to engage a threaded inside diameter
of the lower receiver of a firearm. The receiver extension 230
illustrated in FIG. 2 has a length appropriate for a rifle
configuration of a firearm such as an AR-15.
[0033] 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.
[0034] The liner 250 may, as shown in FIGS. 2-4, be formed from a
sheet of material that is rolled into a tubular shape and inserted
into the bore of the receiver extension such that a seam 252
extends longitudinally along a side of the bore. Alternatively, the
liner may be formed in as a tube or may be sprayed or otherwise
applied to an interior sidewall 236 of the extension 230.
[0035] 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.
[0036] 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.
[0037] Embodiments of the buffer assembly 200 also comprise a
buffer 300. The buffer is shown in more detail in FIGS. 11-18. The
buffer may include a buffer body 320 and a buffer head 322. The
buffer body includes a reduced diameter nose portion 324 at a rear
end of the buffer body, a generally cylindrical central portion
326, and a bearing surface or guide ring 328 at a forward end of
the buffer body 320. The guide ring 328 has a larger diameter than
the central portion 326, forming a shoulder 330 where the two
sections meet. The guide ring 328 is generally cylindrical, but may
have one or more flat or concave portions 332 formed at intervals
around its circumference. The guide ring may act as a bearing
surface between the buffer body 320 and an interior surface of the
receiver extension 230 or liner 250.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] 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.
[0042] 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.
[0043] 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.
[0044] 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.
[0045] As illustrated in FIG. 41, the buffer head 322 is easily
removable, while the rest of the system remains inside the rifle.
This way, the operator may make changes to the buffer mass without
requiring tools or cleaning supplies. The user is not required to
remove the greased or otherwise chemically treated components from
the rifle. In embodiments of the present invention, the buffer head
322 is not otherwise affixed to the buffer body 320; it is
maintained between the carrier (104) and buffer body 320 by the
buffer spring 260 tension. When the rifle is "opened" to allow
cleaning or maintenance, the buffer retainer 352 is responsible for
keeping the buffer head contained.
[0046] Returning to FIGS. 2-4, embodiments of the buffer assembly
200 further comprise a damper assembly 400. The damper assembly 400
is shown in more detail in FIGS. 19-25. The damper assembly 400 is
positioned adjacent the rear end of the receiver extension 230. The
assembly comprises a damper post 410 and a damper ball 430. The
damper post 410 comprises a central section 412 with a generally
cylindrical shape. The damper post further comprises a nose section
414 having a reduced diameter at a forward end of the damper post
and a head section 416 at a rearward end of the damper post. The
head 416 has a diameter that is larger than the diameter of the
central section 412. The damper post 410 extends for forward from
the rear end of the receiver extension, thereby spacing the nose
portion 414 some distance from a rear end of the receiver
extension. Preferably, the spaced distance is greater than the
diameter of the receiver extension bore 234 for rifle embodiments
illustrated in FIGS. 2-4. The length of the post 410 may act as a
guide rod to maintain control of the spring 260 as it compresses
and extends.
[0047] 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.
[0048] 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.
[0049] 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.RTM. 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.
[0050] 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.
[0051] FIGS. 5-10 illustrate the recoil stroke of the buffer
assembly 200. FIG. 6 shows the buffer assembly in fully forward
position, for example when the bolt of the firearm is closed at the
beginning of the firing portion of the firearm's cycle. As the bolt
(106) and bolt carrier (104) of the firearm begin to move backward,
the buffer 300 is driven backward within the bore 234 of the
receiver extension 230. At the end of the rearward stroke, the nose
portion 324 of the buffer body 320 contacts the damper ball 430
attached to a forward end of the damper post 410. The movement of
the buffer 300 causes the weight 350 to move back and forth within
the buffer body cavity 334.
[0052] FIGS. 26-28 shows a buffer assembly 1200 in accordance with
embodiments of the present invention. The buffer assembly 1200 is
generally similar to the buffer assembly embodiments shown in FIGS.
2-4 except that it is adapted for use with a carbine configuration
of a firearm. Accordingly, the receiver extension 1230 illustrated
in FIG. 26 has a length appropriate for a carbine configuration of
a firearm such as an AR-15. In addition, the damper post (410) of
the rifle configuration is replaced with a damper disc 510.
[0053] Embodiments of the buffer assembly 1200 comprise a damper
assembly 500. The damper assembly 500 is shown in more detail in
FIGS. 35-40. The damper assembly 500 is positioned adjacent the
rear end of the receiver extension 1230. The assembly comprises a
damper disc 510 and a damper ball 430. The damper disc 510
comprises a central section 512 with a generally cylindrical shape.
The damper disc further comprises a nose section 514 having a
reduced diameter at a forward end of the damper disc and a head
section 516 at a rearward end of the damper disc. The head 516 has
a diameter that is larger than the diameter of the central section
512.
[0054] 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.
[0055] 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.
[0056] 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.
[0057] FIGS. 29-34 illustrate the recoil stroke of the buffer
assembly 1200 similar to that shown in FIGS. 5-10.
* * * * *