U.S. patent application number 14/730141 was filed with the patent office on 2015-12-03 for compact anti-tilt follower for an ammunition magazine.
The applicant listed for this patent is Magpul Industries Corp. Invention is credited to Eric Burt, Nicholas Kielsmeier, Brian L. Nakayama, Eric Nakayama.
Application Number | 20150345882 14/730141 |
Document ID | / |
Family ID | 54701322 |
Filed Date | 2015-12-03 |
United States Patent
Application |
20150345882 |
Kind Code |
A1 |
Nakayama; Brian L. ; et
al. |
December 3, 2015 |
COMPACT ANTI-TILT FOLLOWER FOR AN AMMUNITION MAGAZINE
Abstract
A follower for a firearm magazine is disclosed. In one
embodiment, the follower has a top platform, a proximal end, a
distal end, and at least one slider rail. The top platform is
shaped to seat a cartridge and has a cartridge case shoulder
region, a cartridge case head region, and a distal region. The
proximal end has a first surface shaped to engage a proximal
interior region of a firearm magazine housing. The distal end has a
second surface shaped to engage a distal interior region of the
firearm magazine housing. The slider rail is on a side of the
follower and extends down from the top platform at a position that
is between and remote from both the proximal end of the follower
and the distal end of the follower. The follower does not have a
slider rail extending from or adjacent to the second surface of the
follower.
Inventors: |
Nakayama; Brian L.; (Arvada,
CO) ; Kielsmeier; Nicholas; (Denver, CO) ;
Nakayama; Eric; (Broomfield, CO) ; Burt; Eric;
(Broomfield, CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Magpul Industries Corp |
Boulder |
CO |
US |
|
|
Family ID: |
54701322 |
Appl. No.: |
14/730141 |
Filed: |
June 3, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62007270 |
Jun 3, 2014 |
|
|
|
Current U.S.
Class: |
42/50 |
Current CPC
Class: |
F41A 9/70 20130101 |
International
Class: |
F41A 9/70 20060101
F41A009/70; F41A 9/65 20060101 F41A009/65 |
Claims
1. A follower for a firearm magazine, the follower comprising: a
top platform shaped to seat a cartridge, the top platform including
a cartridge case shoulder region shaped to abut at least a distal
region of a cartridge case of the cartridge, a cartridge case head
region shaped to abut a case head of the cartridge, and a distal
region associated with a tip of the cartridge; a proximal end
including a first surface shaped to engage a proximal interior
region of a firearm magazine housing; a distal end including a
second surface shaped to engage a distal interior region of the
firearm magazine housing; and at least one slider rail on a side of
the follower; wherein the at least one slider rail extends down
from the top platform at a position that is between and remote from
both the proximal end of the follower and the distal end of the
follower; and the follower does not have a slider rail extending
from or adjacent to the second surface of the follower.
2. The follower of claim 1, wherein: the at least one slider rail
is located closer to a center of gravity of the follower than to
the distal end of the follower.
3. The follower of claim 2, wherein: the at least one slider rail
is located distal of the center of gravity of the follower.
4. The follower of claim 1, wherein: the at least one slider rail
is located distal of a center of gravity of the follower.
5. The follower of claim 1, wherein: the at least one slider rail
extends below the top platform at least a portion of a length of
the side of the follower; and the at least one slider rail has a
curvature shaped to guide the follower along a curvature of a
bearing rail in the firearm magazine housing.
6. The follower of claim 5, wherein: the second surface has a
curvature shaped to conform to a curvature of the distal interior
region of the firearm magazine housing.
7. The follower of claim 6, wherein: the curvature of the at least
one slider rail is not identical to the curvature of the second
surface.
8. The follower of claim 1, wherein: the distal region of the top
platform is tapered between the cartridge case shoulder region and
the distal end of the follower, such that the cartridge case
shoulder region is wider than the distal end of the follower.
9. The follower of claim 1, comprising: a plurality of slider
rails, wherein the at least one slider rail opposes a second one of
the plurality of slider rails.
10. The follower of claim 1, comprising: a plurality of slider
rails on the side of the follower.
11. The follower of claim 1, wherein: the slider rail has a
longitudinal length and a width, the length at least 1.5 times the
width.
12. The follower of claim 11, wherein: the length is at least 5
times the width.
13. The follower of claim 12, wherein: the length is at least 10
times the width.
14. The follower of claim 13, wherein: the length is at least 15
times the width.
15. The follower of claim 1, wherein: the at least one slider rail
comprises a protrusion on the side of the follower or a recess in
the side of the follower.
16. A magazine assembly for storing and feeding cartridges to a
chamber of a firearm, the magazine assembly comprising: a housing
having a distal side and at least one curved bearing rail on an
inside surface of the housing; a follower having a top platform
shaped to seat a cartridge, the top platform including a cartridge
case shoulder region shaped to abut at least a distal region of a
cartridge case of the cartridge, a cartridge case head region
shaped to abut a case head of the cartridge, and a distal region
associated with a tip of the cartridge, the follower further
comprising: a proximal end including a first surface shaped to
engage a proximal interior region of the housing; a distal end
including a second surface shaped to engage a distal interior
region of the housing; and at least one slider rail on a side of
the follower; extending from the top platform at a position that is
remote from both the proximal end of the follower and the distal
end of the follower, the at least one slider rail shaped to engage
the at least one curved bearing rail of the housing; wherein the
follower does not have a slider rail extending from or adjacent to
the second surface of the follower; and a follower spring between
the follower and a floor of the housing to apply a biasing force on
the follower.
17. The magazine assembly of claim 16, wherein: the housing
comprises a longitudinal axis; the biasing force comprises a
longitudinal component associated with the longitudinal axis; and
the at least one slider rail and the at least one bearing rail are
shaped and positioned to maximize the longitudinal component of the
biasing force at a center of gravity of a cartridge placed in the
magazine assembly.
18. A follower for a firearm magazine, the follower comprising: a
top platform shaped to seat a cartridge, the top platform having a
distal region, a case shoulder region, and a case head region; a
proximal end; a distal end having a tapered tip; and a first
elongated protrusion on a first side of the follower, the first
elongated protrusion having a curved longitudinal axis shaped to
slidably engage a first curved recess in a first side of the
housing; a second elongated protrusion on a second side of the
follower, the second elongated protrusion having a curved
longitudinal axis shaped to slidably engage a second curved recess
in a second side of the housing; wherein the first elongated
protrusion and the second elongated protrusion are positioned on
opposing sides of the follower; and the first elongated protrusion
and the second elongated protrusion are more proximal to the case
shoulder region of the top platform than to the case head region of
the top platform.
19. The follower of claim 18, wherein: the first elongated
protrusion and the second elongated protrusion are positioned
closer to a center of gravity of the follower than to the proximal
end of the follower; and the first elongated protrusion and the
second elongated protrusion are positioned closer to the center of
gravity of the follower than to the distal end of the follower.
20. The follower of claim 18, wherein: the first elongated
protrusion has a longitudinal first length and a first width, the
first width measured from a proximal side of the first elongated
protrusion to a distal side of the first elongated protrusion, the
first length being at least 10 times the first width; the second
elongated protrusion has a longitudinal second length and a second
width, the second width measured from a proximal side of the second
elongated protrusion to a distal side of the second elongated
protrusion, the second length at least 10 times the second width.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 62/007,270 filed Jun. 3, 2014 and entitled "COMPACT
ANTI-TILT FOLLOWER FOR AN AMMUNITION MAGAZINE," the entire
disclosure of which is hereby incorporated by reference for all
purposes, as if fully set forth herein.
COPYRIGHT
[0002] A portion of the disclosure of this patent document contains
material that is subject to copyright protection. The copyright
owner has no objection to the facsimile reproduction by anyone of
the patent disclosure, as it appears in the Patent and Trademark
Office patent files or records, but otherwise reserves all rights
available and provided by copyright law.
FIELD OF THE INVENTION
[0003] The present invention relates to the field of firearms. In
particular, but not by way of limitation, the present invention
relates to an improved follower and casing for an ammunition
magazine.
BACKGROUND OF THE INVENTION
[0004] Firearm magazines are regularly used with firearms to allow
for convenient storage and feeding of multiple cartridges to a
firearm. Traditional magazines generally have a spring-loaded
follower for guiding cartridges through the magazine housing to the
top or mouth of the magazine where a firearm bolt can push one
cartridge at a time into a chamber of the firearm. Although
traditional magazines are generally functional, many types may be
prone to jamming, can be unreliable, or are otherwise
unsatisfactory. Moreover, it is desirable to provide for smaller or
more compact followers and/or smaller magazine housings.
Accordingly, a system and method are needed to address the
shortfalls of present technology and to provide other new and
innovative features.
SUMMARY
[0005] Exemplary aspects of the present disclosure that are shown
in the drawings are summarized below. The word "exemplary" is used
herein to mean "serving as an example, instance, or illustration."
Any embodiment or aspect described herein as "exemplary" is not
necessarily to be construed as preferred or advantageous over other
embodiments or aspects.
[0006] In one example, the follower has a top platform, a proximal
end, a distal end, and at least one slider rail. The top platform
is shaped to seat a cartridge and has a cartridge case shoulder
region, a cartridge case head region, and a distal region. The
proximal end has a first surface shaped to engage a proximal
interior region of a firearm magazine housing. The distal end has a
second surface shaped to engage a distal interior region of the
firearm magazine housing. The slider rail is on a side of the
follower and extends down from the top platform at a position that
is between and remote from both the proximal end of the follower
and the distal end of the follower. The follower does not have a
slider rail extending from or adjacent to the second surface of the
follower.
[0007] In another example, a magazine assembly for storing and
feeding cartridges to a chamber of a firearm is provided. The
magazine assembly has a housing, a follower, and a spring. The
housing has a distal side and at least one curved bearing rail on
an inside surface of the housing. The follower has a top platform
shaped to seat a cartridge, the top platform including a cartridge
case shoulder region shaped to abut at least a distal region of a
cartridge case of the cartridge, a cartridge case head region
shaped to abut a case head of the cartridge, and a distal region
associated with a tip of the cartridge. The follower also has a
proximal end including a first surface shaped to engage a proximal
interior region of the housing, a distal end including a second
surface shaped to engage a distal interior region of the housing;
and at least one slider rail. The at least one slider rail is on a
side of the follower, extending from the top platform at a position
that is remote from both the proximal end of the follower and the
distal end of the follower. The at least one slider rail is shaped
to engage the at least one curved bearing rail of the housing. The
follower spring is between the follower and a floor of the housing
to apply a biasing force on the follower. The follower does not
have a slider rail extending from or adjacent to the second surface
of the follower.
[0008] In another example, a follower is provided, having a top
platform, a proximal end, a distal end, a first elongated
protrusion, and a second elongated protrusion. The top platform is
shaped to seat a cartridge and has a distal region, a case shoulder
region, and a case head region. The distal end has a tapered tip.
The first elongated protrusion is on a first side of the follower
and has a curved longitudinal axis shaped to slidably engage a
first curved recess in a first side of the housing. The second
elongated protrusion is on a second side of the follower and has a
curved longitudinal axis shaped to slidably engage a second curved
recess in a second side of the housing. The first elongated
protrusion and the second elongated protrusion are positioned on
opposing sides of the follower. The first elongated protrusion and
the second elongated protrusion are more proximal to the case
shoulder region of the top platform than to the case head region of
the top platform.
[0009] These and other examples and aspects are more fully
described in the Detailed Description section. It is to be
understood, however, that there is no intention to limit the
invention to the forms described in this Summary or in the Detailed
Description. One skilled in the art can recognize that there are
numerous modifications, equivalents and alternative constructions
that fall within the spirit and scope of the invention as expressed
in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Various objects and advantages and a more complete
understanding of the present invention are apparent and more
readily appreciated by reference to the following Detailed
Description and to the appended claims when taken in conjunction
with the accompanying Drawings wherein:
[0011] FIG. 1 is a perspective view of an embodiment of a magazine
assembly.
[0012] FIG. 2 is a perspective view of a housing of the magazine
assembly in FIG. 1.
[0013] FIG. 2A is a detailed view of a top portion of the magazine
assembly housing in FIG. 1.
[0014] FIG. 3 a perspective view of the follower in FIG. 1.
[0015] FIG. 3A is a perspective view of a portion of another
embodiment of a follower.
[0016] FIG. 4 is a top view of the magazine assembly.
[0017] FIG. 5 is a top view of another embodiment of a magazine
assembly.
[0018] FIG. 5A is a top view of a portion of another embodiment of
a magazine assembly.
[0019] FIG. 6 is a perspective view of another embodiment of a
magazine assembly.
[0020] FIG. 6A is a detailed view of a top portion of the magazine
assembly in FIG. 6.
[0021] FIG. 7 is a perspective view of another embodiment of a
magazine assembly.
[0022] FIG. 8 is a perspective view of a housing of the magazine
assembly in FIG. 7.
[0023] FIG. 9 is a perspective view of a follower of the magazine
assembly in FIG. 7.
DETAILED DESCRIPTION
[0024] As discussed above, in one exemplary embodiment the present
disclosure describes a compact anti-tilt follower for a firearm
magazine as will be described below. The follower can be produced
in a more compact fashion (e.g., having a shorter overall height)
by using a substantially vertical slider rail along one or more
sides of the follower having a greater aspect ratio (length over
width) than prior art anti-tilt features. The greater aspect ratio
enables more anti-tilt effect from the slider than prior-art
designs and thereby enables a shorter follower with the same or
better anti-tilt abilities than prior art designs. Advantages of a
more compact follower are less friction with an inside of a
magazine housing and a magazine that can potentially house more
cartridges. In another exemplary embodiment, this disclosure
describes a housing for a firearm magazine, which will be described
in further detail below. In a third exemplary embodiment, the
disclosure describes a magazine assembly having a compact anti-tilt
follower and a firearm magazine housing as described below.
[0025] Referring now to the drawings, where like or similar
elements are designated with identical reference numerals
throughout the several views, FIG. 1 illustrates an embodiment of a
magazine assembly 100 for storing and feeding cartridges to a
chamber of a firearm. The magazine assembly 100 comprises a housing
102 and a follower 104. The follower 104 is assembled within the
housing 102, and is configured to guide cartridges towards an exit
or feed lips of the housing 102. Although not depicted, it will be
understood by those skilled in the art that the magazine assembly
100 may include other components, such as a spring for
spring-loading the follower 104 within the housing 102, as well as
a bottom end for affixing a spring-loaded follower 104 to the
housing 102. Similarly, some of the various components of the
magazine assembly 100 disclosed herein may be manufactured as a
unitary component, or they may be assembled/coupled together to
create the components discussed.
[0026] Referring now to FIG. 2, the housing 102 is discussed in
more detail. The housing 102 may be manufactured of high strength
synthetic materials, plastics, composites, ceramics, various metals
including aluminum, stainless steel or alloys, or any other
material suitable for the intended use with a firearm, and it may
have a surface finish suitable to minimize friction with a follower
104 therein, as well as an external profile suitable for handling.
A top end 106 of the housing 102 is configured to attach to a
firearm (e.g., to mate with a magazine well), as well as to control
the feeding of cartridges into the firearm chamber most often by a
feed lip at the top end 106. The housing 102 may be configured to
be permanently attached to a firearm, for example as part of an
internal box or fixed magazine, or the housing 102 may be
configured to be removably attached to a firearm, for example as a
detachable box magazine. The top end 106 may be configured to guide
double-stacked cartridges into a feed position, or the top end 106
may be configured to guide single-stacked cartridges into a feed
position. The housing 102 may also be configured to guide
cartridges from double or quad stack to single stack formations for
feeding. The stack, whether single, double, or quad stack, may
follow a path that is straight, a planer radius, a spherical
radius, a spiral, a helix or any combination of the preceding.
[0027] Continuing with FIG. 2, a front or distal side 108 of the
housing 102 is shown. For purposes of this disclosure, the term
"distal" shall refer to those portions of a component associated
with the tip or projectile end of a last cartridge in the magazine
assembly 100 (i.e., a cartridge in contact with a top of the
follower). To simplify discussion of the magazine assembly 100, the
remainder of this disclosure will use the terms "a cartridge" or
"the cartridge" to refer to the last cartridge in the magazine
assembly 100. That is, the distal side 108 of the housing 102 is
the side towards which cartridge would point when cartridges are
loaded into the housing 102. Similarly, the housing 102 has a
proximal side 110, with the proximal side 110 being associated with
the primer or case end of cartridge. That is, when loaded into the
housing 102, cartridges would point away from the proximal side 110
of the housing 102.
[0028] The housing 102 may also be curved, as shown in the figures,
to provide for smooth feeding of the cartridges; however, it should
be understood by those skilled in the art that the housing 102 may
be straight in some embodiments. That is, for the purposes of this
disclosure, the term "curvature" may in some embodiments be used to
describe a feature having a curvature of infinite radius that is
straight, a planer radius, a spherical radius, a spiral, a helix or
any combination of the preceding. Moreover, the housing 102 may be
configured to hold relatively few rounds, or up to a hundred rounds
or more, with thirty rounds being a standard capacity in some
embodiments. The top end 106 of the housing 102 may be
interchangeable with other types of magazine housings.
[0029] Referring now to FIG. 2A in light of FIG. 2, a detailed view
of a portion of the housing 102 is shown. FIG. 2A illustrates a
bearing 112 on the inside wall of a side of the housing 102. The
bearing 112 may have two ridges or ribs 112a, 112b protruding from
the inside wall, forming a recess for guiding the follower 104. The
bearing 112 and side of the housing 102 may be molded or machined
as a unitary component, or the bearing 112 may be separately
manufactured and affixed to the inside wall of the side. As
mentioned, the bearing 112 is shown in this embodiment as a recess
created from two ridges protruding from the side of the housing
102. The recess created by the ridges may be of a rectangular shape
for providing a bearing surface for guiding the follower 104 along
a desired path within the housing 102. This square or rectangular
recess may provide for ease of manufacturing, and, as will be
understood by the skilled person, minimize the types of directional
forces each component of the bearing 112 will address. In some
embodiments, portions or all of the housing 102 may be manufactured
of a clear material so as to provide a visual aide to the user. In
some embodiments, the bearing 112 may be a curved bearing rail. In
some embodiments, the bearing 112 may be a recess in the housing
102 (e.g., see 712 in FIG. 7), or the bearing 112 may be formed by
the ribs 112a, 112b as illustrated.
[0030] In FIGS. 2 and 2A, a top portion of the bearing 112 or ribs
112a, 112b is shown. As seen, the bearing extends to a location
just below the exit or feed lips of the housing 102. Similarly, the
bearing 112 may extend the full length of the housing 102, to the
bottom of the housing, to allow the follower 104 to be inserted
into the housing 102 after the sides of the housing 102 have been
assembled. That is, the bearing 112 may allow for the follower 104
and a replacement bottom of the housing 102 to be inserted
after-market. In some embodiments, however, the bearing 112 may
extend only part of the way to a bottom of the housing 102 to allow
only for travel of the follower 104 to a position near, but not at,
the bottom of the housing 102. In such embodiments, it will be
understood that after-market insertion of the follower 104 would
not be possible, which may be advantageous in preventing
misuse.
[0031] The second side of the housing 102 may also have a bearing
112 on the inside wall thereof (not visible in FIG. 2).
[0032] Referring now to FIG. 3, the follower 104 shown in FIG. 1 is
discussed in more detail. The follower 104 may be manufactured of
high strength synthetic materials, plastics, various metals
including stainless steel or alloys, or any other material suitable
for the intended use with a firearm, and it may have a surface
finish suitable to minimizing friction with a housing 102 and/or a
cartridge. The follower 104 has a front or distal end 116, a back
or proximal end 118, a top platform 126, and at least one slider
rail, or slider 120. The top platform 126 can be configured to
guide one or more cartridges towards an exit of the housing 102,
and has a distal region, a case shoulder region, and a case head
region. The distal region corresponds to a tip of the cartridge,
the case shoulder region corresponds to a shoulder 128 of the
cartridge case, and the case head region corresponds to a case head
130 of the cartridge. The proximal end 118 may have a first surface
shaped to engage a proximal interior region 109 of the housing, and
the distal end 116 may include a second surface shaped to engage a
distal interior region 111 of the housing, as illustrated in FIG.
2. Of note, the slider 120 extends from the top platform 126 at a
position that is between and remote from both the proximal end 118
of the follower and the distal end 116 of the follower. The slider
may be an elongated protrusion, and may be curved or straight. The
slider 120 may also have a greater aspect ratio than anti-tilt
devices known in the art (e.g., having a greater ratio of length
(L) to width (W)), thereby enabling a more compact follower with
the same if not better anti-tilt capabilities.
[0033] The slider 120 is configured to control the tilt of the
follower 104 as the follower 104 moves within the housing 102. In
the illustrated embodiment, the slider 120 has a curvature that may
mimic a curvature of an inside of the housing 102 (e.g., a constant
internal curvature). In some embodiments, however, the follower
104, and axis B, may not be curved at all, or not have the same
curvature, even where the bearing 112 is curved, so long as the
tolerances are chosen to allow the follower 104 to smoothly pass
through the housing 102. For example, a slider 120 may have an
infinite curvature (that is, straight), yet still be used in a
curved housing 102. In this straight slider 120 embodiment, the
curvature of the slider 120 does not mimic the curvature of the
inside of the housing 102. Like with the housing 102, the slider
120 may follow a path that is straight, a planer radius, a
spherical radius, a spiral, a helix or any combination of the
preceding. Furthermore, the slider 120 may be partially curved;
that is, the 120 may follow axis B for a portion of the length of
the slider 120, and follow a straight line for another portion of
the length of the slider 120. The axis B may correspond to a
curvature in the bearing 112, but it need not necessarily do
so.
[0034] It will be understood by those skilled in the art and active
in the firearms industry that the general term "tilt" may be used
to describe the tilting about one or more of the pitch, roll, and
yaw axes. In FIG. 3, axis A defines the yaw axis, axis D defines
the roll axis, and axis C defines the pitch axis. If uncontrolled
or unpredictable, this tilt is undesirable, because it adversely
affects weapon reliability. Applicants have developed an elegant
solution to control tilt of the follower 104, thus improving weapon
reliability and safety. Moreover, controlling the tilt of the
follower 104 in this manner results in a more compact design, as
compared to the prior art, and allows an anti-tilt follower to be
used in smaller capacity magazines without utilizing as much space
as the prior art.
[0035] As shown in FIG. 3, the slider 120 may be configured to
interface with the bearing 112 of the housing 102. The slider 120
is configured to prevent the follower 104 from tilting about a
roll, and/or yaw axis and present a desired pitch depending on the
follower's 104 position within the housing 102. In some
embodiments, tilt about the yaw and roll axes are more tightly
controlled than the tilt about the pitch axis. In some embodiments,
the tilt of the follower 104 about the pitch axis is controlled
such that the change in pitch is linearly related to an angular
displacement along a curve within the housing 102. In some
embodiments, the tilt about the pitch, that is, the rotation about
axis C, is controlled so as to vary at an increasing rate or
decreasing rate along the long or yaw axis A.
[0036] As depicted in FIG. 3, the slider 120 may be a protrusion or
rib extending from the side of the follower 104. The slider 120 may
also have in some embodiments a square or rectangular profile, to
match a square or rectangular recess formed by the bearing 112 in
the housing 102, and, as previously discussed, to control the types
of forces the slider 120 may experience. In other embodiments, the
slider 120 may have other profiles, such as having one or more
non-perpendicular angles, one or more beveled edges, one or more
curved edges (e.g., FIG. 5), two or more edges that are oblique to
each other, or at least one edge that is oblique to an inner
surface of the housing 102, to name a few non-limiting examples. It
should also be understood that the slider 120 need not necessarily
extend along the entirety of axis B as shown. A notched slider 120,
wherein the slider 120 protrudes from the side of the follower 104
at various places along axis B is possible. Similarly, the slider
120 may extend along only a portion of the side of the housing 102.
Similarly, the slider 120 may have more or fewer contact surfaces
390 (shown in FIG. 3A) than those shown in FIG. 3. For example, as
shown in FIG. 5, a slider 520 having a half-moon profile provides
for one contact surface. As another example, the slider 520 may
have a series of projections 520a, 520b (shown in FIG. 5A) that
provide more contact surfaces, with or without the bearing 512
being modified accordingly, as seen in FIGS. 5, 5A and 6A. The
projections may follow a linear path, as shown in FIG. 6A, or they
may follow a curved path, as shown in FIG. 5A, or any other path
desired, and the projections themselves may curved, when viewed
from the top, as shown in FIG. 5A, or squared, as shown in FIG. 6A,
or the projections may have any other shape desired, to allow the
follower 104 to travel unhindered through the housing 102. In some
embodiments, a greater ratio of length L to thickness T than is
provided in currently-available designs may also provide for the
ability to reduce an overall height of the follower 104.
[0037] Continuing with FIG. 3, the slider 120 may have a greater
aspect ratio than prior art followers. A greater aspect ratio
enhances the anti-tilt capability of the follower for a given
length of the follower, and thereby enables a more compact follower
with the same or better anti-tilt capability as prior art designs.
The slider 120 may have a length L and a width W. The length L may
be along a straight or curved longitudinal axis B as illustrated,
and the width W may be a measurement of the slider 120
perpendicular to the longitudinal axis B. A thickness T may be a
maximum distance the slider 120 protrudes from the side of the
follower. The thickness T may also be, in the alternative, a
maximum depth the slider 120 can recede into a recess in the side
of the follower (e.g., see bearing 712 in FIG. 7). An aspect ratio
of the length L to the width W may be selected such that the
follower may be compacted (e.g., a shorter length L can be used
while still maintaining or improving upon the anti-tilt capability
of a follower with a longer length L). That is, the length L may be
at least 1.5 times the width W, resulting in an aspect ratio of
1.5. In some embodiments, the length L is at least 5 times the
width W, for an aspect ratio of 5. In some embodiments, the length
L is at least 10 times the width W, for an aspect ratio of 10. Of
note, the larger aspect ratios are achievable by providing a slider
120 with a narrow width W, as measured from the distal side to the
proximal side of the slider 120. That is, in contrast to followers
that are currently available in which the width W is generally
maximized, Applicants have developed a slider 120 in which the
width W is generally minimized and/or reduced so as to allow an
aspect ratio of 1.5, 5, 10, 15 or more. Of note, in the embodiment
illustrated in FIG. 3, the aspect ratio is greater than 10, and
greater than 15, or about 16. However, this disclosure is not
limited to aspect ratios between 1.5 and 16, and larger aspect
ratios are also envisioned.
[0038] It should be understood by those skilled in the art that the
terms "slider" and "bearing" are not intended to limit this
disclosure to the protrusion and channel shown. Instead, it should
be understood that the term "slider" is meant to indicate the
moving component, i.e., the portion of the follower 104 that moves
within the housing 102. Likewise, it should be understood that the
term "bearing" is merely meant to indicate the stationary
component, i.e., the portion of the housing 102 that guides the
movement of the follower 104. It should be understood that the
elements can be reversed while preserving the function, with the
housing 102 having a protruding bearing and the follower 104 have a
recessed slider. Likewise, where two sliders and two bearings are
implemented, it should be understood that one slider may be
protruding while the second is recessed.
[0039] As can be seen in FIG. 3, the yaw axis, or axis A, defined
as an axis extending along the center of the distal end 116 of the
follower 104, may be curved; this curve is intended to complement a
curve of the distal side 108 of the housing 102, thereby allowing
the follower 104 to pass unhindered through the housing 102. The
proximal end 118 of the follower 104 may also have a complementary
curve intended to match the curve at the proximal side 110 of the
housing 102. It should be understood that, where the housing 102 is
not curved, the yaw axis may or may not be curved. Like with the
slider 120 discussed above, it should be understood that, in some
embodiments, the yaw axis is not curved at all, even where the
housing 102 is curved, so long as the tolerances are chosen to
allow the follower 104 to smoothly pass through the housing
102.
[0040] In FIG. 3, the follower 104 is shown with protrusions 124
near the proximal end 118. These protrusions 124 provide for added
control of the tilt of the follower 104. It should be understood by
those skilled in the art that numerous alternate profiles of the
protrusions 124 can be used. For example, the protrusions 124 may
have one or more non-perpendicular angles, one or more beveled
edges, one or more curved edges, two or more edges that are oblique
to each other, or at least one edge that is oblique to an inner
surface of the housing 102, to name a few non-limiting
examples.
[0041] Referring briefly back to FIG. 2, the housing 102 may have a
housing taper 114 at the distal side 108 of the housing 102. The
housing taper 114 provides advantages in certain embodiments.
First, the housing taper 114 assists in determining proper
orientation of the magazine assembly, in turn improving response
time and/or limiting potential damage to the top end 106 from
attempts to improperly attach the housing 102 to a firearm.
Moreover, the housing taper 114 may enable those wearing gloves or
those with smaller hands to more firmly and quickly grasp the
housing 102 during outdoor use in inclement weather, or use while
under the stress of combat. A housing 102 with a taper have a
smaller perimeter than a housing of the same overall width and
height without such a feature. The housing taper 114 may provide
the ability to reduce the overall size of the housing 102 and is
particularly suited to embodiments in which a bottle neck
cartridge, spitzer or spire point bullets, or other types of
ammunition having a relatively narrower tip or distal end, are
used. Material usage is also reduced when the housing taper 114 is
present. As illustrated, the taper 114 can extend down a portion of
the housing 102 and can extend from a top to a bottom of the
housing 102. However, in other embodiments, the taper 114 may
extend only part way to the bottom of the housing 102 such that a
portion of the housing 102 has a fully rectangular profile when
viewed from above or from the bottom.
[0042] Returning again to FIG. 3, it can be seen that the follower
104 may likewise have a follower taper 122 at the distal end 116,
with the follower taper 122 corresponding to the housing taper 114
in the housing 102. When used with a housing 102 having a housing
taper 114, the advantages previously discussed are realized.
[0043] In FIG. 3, the slider 120 is shown located along an axis B
that is parallel to, and offset from axis A, More specifically, the
slider 120 is located closer to the proximal end 118 than both axis
A and the follower taper 122 at the distal end 116. FIG. 3 also
illustrates in phantom the relationship between a last cartridge
and the follower 104, or where the last cartridge would sit when
the follower 104 is guiding cartridges through the housing 102. As
seen, the desired location of the slider 120 is near to the
cartridge shoulder in housings 102 where it is desirable to
minimize the width; more specifically, it is desirable that the
slider 120 be located near or at a center of the follower 104. That
is, the slider 120 may be positioned to balance forces on the
cartridge about the center of gravity of the cartridge, thus
controlling tilt of the cartridge and follower 104 about a pitch
axis. By locating the slider 120 about the center of gravity and
near the extreme sides, the leverage or applied moment that would
cause the follower 104 to pitch or roll can be reduced. Similarly
and relatedly, placing the slider 120 near the geometric center of
the follower 104 reduces forces applied to the follower 104 from
foreign objects caught between the follower 104 and the housing
102. It will be understood by those skilled in the art that
rotation about a pitch axis is associated with a dive or ascent of
the distal end 116 relative to a level plane.
[0044] Locating the slider 120 near the center of gravity therefore
provides more stability to the follower 104 when it is being guided
through the housing 102, as compared to the prior art. Due to the
geometry most often required for both the cartridge and the
magazine interface, the most practical location is often is near to
the cartridge shoulder in the housing 102. This location also
allows for a reduction in the size required from the top of the
follower 126 to the bottom 127 of the follower 104. In turn, the
follower 104 is more compact than prior art followers, and, where
the spring geometry allows, a particularly compact housing 102 may
be constructed for use with the compact follower 104 described
herein.
[0045] The slider 120 may be on a side of the follower 104, and a
second slider 120 may be on an opposing side of the follower 104.
Although depicted as extending along the entire length of the side
of the follower 104, it should be understood that the slider 120
need not necessarily extend along the entire length of the side.
All that is necessary is that the slider 120 extend far enough so
as to ensure that tilt is controlled to an acceptable tolerance
when the follower 104 is traveling through the housing 102 of the
magazine 100. In some embodiments, the slider 120 can have a
profile, when viewed from above, resembling at least a portion of a
rectangle, square, circle, pill-shape, multi-faceted shape, and
many others. Moreover, the slider 120 may be interrupted at one or
more portions between the top 126 and the bottom 127 of the
follower (e.g., an "interrupted slider"). An interrupted slider may
also exhibit various profile features or projections 390 when
viewed from the side, as seen in FIG. 3A. For example, circular,
cylindrical, rectangular, square, multi-faceted, pill-shaped, or
other types of projections 390 may be exhibited when viewed from
the side. Such features may form an effective curve by their shape
and relative position to one another. The axis B of the slider 120
may also be curved in a manner to complement the curvature of the
yaw axis A and the curve at the distal side 108 of the housing 102
to enable smooth travel through the housing 102.
[0046] As can further be seen in FIG. 3, the slider 120 of the
follower 104 may have a profile that is square or rectangular in
shape when viewed from the top. However, in some embodiments, and
as shown in FIG. 4, which depicts another embodiment of the
magazine assembly 400, the profile of the slider 420 may be
trapezoidal in shape, with a complementary trapezoidal bearing 412
in the housing 402, as shown in FIG. 4. This trapezoidal shape may
be implemented to optimize or otherwise control any shearing forces
that may arise at the interface between the bearing 412 and the
slider 420 of the follower 404.
[0047] Similarly, FIG. 5 is a top view of another embodiment of the
magazine assembly 500 having a housing 502 and a follower 504, in
which the bearing 512 and complementary slider 520 have a circular
profile when viewed from the top. Again, this variation may be used
to control shearing forces that may arising when the bearing 512
and the slider 520 bear against or slide across one another. Other
curved profiles such as those including one or more elliptical or
parabolic curves can also be implemented.
[0048] FIG. 6 depicts another embodiment of the magazine assembly
600, in which the bearing 612 comprises a series of three
protrusions 612a, 612b, 612c on the inner wall of the housing 602,
with the three protrusions 612a, 612b, 612b, creating a set of two
recesses. Likewise, the slider 620 may comprise a set of two
protrusions complementary to the two recesses created by the
bearing 612 in the housing 602. This series of protrusions 612a,
612b, 612c for interfacing with the slider 620 provides redundancy
in the interface of the magazine assembly 600. This redundancy
provides for continued functionality in the event one of the
components breaks, i.e. avoiding immediate degradation of function
or potential failure. This embodiment may be used to reduce the
protrusion of each while minimizing the interior intrusion. As
further shown in FIG. 6, a housing taper 614 may also be provided,
giving, as previously discussed with other embodiments, the
advantages associated with a smaller circumference about the
housing 602.
[0049] Turning now to FIGS. 7-9, an embodiment of a magazine
assembly 700 having a housing 702 and a follower 704 is depicted.
As seen in FIG. 8, the housing 702 is a straight box type housing
702 for use with fewer rounds than the housings illustrated in
FIGS. 1-6. For example, as few as three rounds are contemplated for
use with this embodiment. The housing 702 may include a ledge 730
at one or both of the distal corners of the housing 702, to provide
a stop feature, thereby preventing the follower 704 from sliding
out of the housing after a last cartridge is removed from the
housing 702. The follower 704, as shown in FIG. 9, may include a
complementary recess 732 for abutting the ledge 730 of the housing
702. In this embodiment, the follower 704 achieves the compact
anti-tilt features by locating the slider 720 at a position that is
removed from the distal end 716 of the follower 704, as seen in
FIG. 9.
[0050] The embodiment shown in FIG. 9 illustrates how the anti-tilt
function is maintained in magazines having a smaller capacity, even
without lengthening the design of the follower 704. To better
understand the embodiment shown in FIG. 9, however, a description
of the prior art is useful. First, for followers intended for use
in magazines having a smaller capacity, the length of the follower
in the prior art is relatively long, because of various downward
projections needed to provide an anti-tilt function. In turn, this
necessitates a longer housing to accommodate the long follower, as
compared to a tiltable follower having little or no downward
projections (no anti-tilt function). In contrast, the embodiment of
the anti-tilt follower 704 shown in FIGS. 7-9 does not limit the
design of the housing 702 in the same manner, thus enabling both a
smaller housing 702 and a smaller capacity magazine, as compared to
prior art followers. Moreover, a family of magazines of different
capacities may be compatible with the same compact anti-tilt
follower, and the smaller capacity magazine does not need to be as
long as is required in the prior art.
[0051] As can be seen in FIGS. 7-9, in some embodiments the slider
720 of the follower 704 does not necessarily have the same profile
as the bearing 712. Moreover, this varied profile may be adapted
for use in one or more of the embodiments discussed with reference
to FIGS. 1-6. That is, those skilled in the art will understand
that, in any or all embodiments, a minimum number of contact
surfaces may be chosen so as to sufficiently constrain tilt without
overburdening friction and/or manufacturing constraints and
tolerances.
[0052] Although the figures depict a follower 104 having a
mirror-image slider 120 on both sides of the follower 104, it
should be understood that this disclosure encompasses embodiments
in which the follower 104 has only one slider 120, or in which two
or more sliders 120 are not mirror images. As a non-limiting
example, one slider 120 may have a square profile, while the other
may have a round profile and/or be offset from the first slider
120. As another example, a first slider 720 may be configured to
control most of the tilt requirements having looser tolerances,
while a second slider 120 may be configured to engage only where
tighter tolerances are required. That is, for example, a first
slider 120 might control overall length of travel, while a second
slider 120 may be configured to engage only where the follower 104
begins to tilt too far out of a desired tilt range. Such variations
may provide advantages in manufacturing, such as loosening
manufacturing tolerances for some components of the slider 104 or
housing 102 while still maintaining strict control over the
movement of the follower 104, and thus the overall reliability of
the magazine assembly 100 itself.
[0053] Although the figures depict followers 104, 604, 704 having a
top platform 126 that is flat, it should be understood that this
disclosure encompasses the use of any top platform profile suitable
for the intended use of feeding cartridges to a firearm chamber. As
just a few examples, this disclosure contemplates a follower 104
having a rounded top platform, either concave or convex, as well as
embodiments in which the top platform includes a ramp for shifting
forces exerted on a cartridge, and top platforms having an angle to
minimize contact area. Some top platforms encompassed by this
disclosure are discussed in commonly-assigned U.S. Pat. No.
8,166,692 issued May 1, 2012, the contents of which are
incorporated by reference herein in their entirety; however, it
should be understood that other top platform profiles are
encompassed.
[0054] It should also be understood that the compact anti-tilt
follower 104 and housing 102 of any of the preceding embodiments
can be adapted for use with ammunition of a variety of calibers, as
well as a variety of firearm classes that use magazines for feeding
multiple rounds to the firearm.
[0055] In conclusion, the present invention provides, among other
things, a compact anti-tilt follower for guiding cartridges towards
an exit of a housing of a firearm magazine. The invention may
include a housing for a firearm magazine configured to guide an
anti-tilt follower through the housing, and it may include an
assembly having a compact anti-tilt follower and housing. Those
skilled in the art can readily recognize that numerous variations
and substitutions may be made in the invention, its use, and its
configuration to achieve substantially the same results as achieved
by the embodiments described herein. Accordingly, there is no
intention to limit the invention to the disclosed exemplary forms.
Many variations, modifications and alternative constructions fall
within the scope and spirit of the disclosed invention as expressed
in the claims.
* * * * *