U.S. patent application number 13/655605 was filed with the patent office on 2013-07-04 for bullet with chamber sealing structure and ammunition comprising same.
This patent application is currently assigned to ENGEL BALLISTIC RESEARCH INC.. The applicant listed for this patent is ENGEL BALLISTIC RESEARCH INC.. Invention is credited to John Whitworth Engel, Chris Luchini.
Application Number | 20130167747 13/655605 |
Document ID | / |
Family ID | 48693796 |
Filed Date | 2013-07-04 |
United States Patent
Application |
20130167747 |
Kind Code |
A1 |
Luchini; Chris ; et
al. |
July 4, 2013 |
BULLET WITH CHAMBER SEALING STRUCTURE AND AMMUNITION COMPRISING
SAME
Abstract
A round of ammunition for use in a 5.56 NATO-specification
chamber comprises a cartridge casing and a bullet having a casing
engaging segment, a sealing band and a groove. The sealing band
encircles the casing engaging segment. The casing engagement
segment of the bullet is engaged within a bullet receiving opening
of the cartridge casing with a rear surface of the sealing band
abutting a front edge of the cartridge casing. The groove encircles
the casing engagement segment. A rear portion of the sealing band
intersects a front portion of the groove. A front face of the
sealing band is substantially flat. An angle of the front face of
the sealing band is approximately the same as an angle of a
neck-to-throat transition portion of the 5.56 NATO-specification
chamber.
Inventors: |
Luchini; Chris; (Los Alamos,
NM) ; Engel; John Whitworth; (Smithville,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ENGEL BALLISTIC RESEARCH INC.; |
Smithville |
TX |
US |
|
|
Assignee: |
ENGEL BALLISTIC RESEARCH
INC.
Smithville
TX
|
Family ID: |
48693796 |
Appl. No.: |
13/655605 |
Filed: |
October 19, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13066780 |
Apr 25, 2011 |
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13655605 |
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12800879 |
May 25, 2010 |
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13066780 |
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Current U.S.
Class: |
102/439 ;
102/524 |
Current CPC
Class: |
F42B 5/067 20130101;
F42B 14/02 20130101 |
Class at
Publication: |
102/439 ;
102/524 |
International
Class: |
F42B 14/02 20060101
F42B014/02; F42B 5/067 20060101 F42B005/067 |
Claims
1. A bullet, comprising: a casing engaging segment defining a rear
face of the bullet; a sealing band encircling the casing engaging
segment; and a groove encircles the casing engagement segment at a
position between the sealing band and the rear face of the bullet,
and wherein a rear portion of the sealing band intersects a front
portion of the groove.
2. The bullet of claim 1 wherein the groove has an arcuate
cross-sectional profile such that a surface of the groove is devoid
of edges.
3. The bullet of claim 1 wherein: the rear portion of the sealing
band includes a rear wall; the front portion of the groove includes
a front wall; and the rear wall of the sealing band intersects the
front wall of the groove.
4. The bullet of claim 1 wherein a volume of the sealing band is
approximately the same as a volume of the groove.
5. The bullet of claim 4 wherein: the groove has an arcuate
cross-sectional profile such that a surface of the groove is devoid
of edges; the rear portion of the sealing band includes a rear
wall; the front portion of the groove includes a front wall; and
the rear wall of the sealing band intersects the front wall of the
groove.
6. The bullet of claim 1 wherein: the sealing band is substantially
symmetric about a longitudinal centerline axis of the casing
engaging segment; the groove is substantially symmetric about the
longitudinal centerline axis of the casing engaging segment; and a
volume of the sealing band is greater than or equal to the volume
of the groove.
7. The bullet of claim 1, further comprising: a rifling leade
mating segment extending from the casing engaging segment forward
of a front portion of the sealing band, wherein the rifling leade
mating segment has a frusto-conical shape tapering from a first
diameter at a first end portion thereof to a second diameter at a
second end portion thereof and wherein the first diameter is
greater than the second diameter; and an ogive portion extending
from the second end portion of the rifling leade mating
segment.
8. The bullet of claim 7 wherein a volume of the sealing band is
greater than or equal to the volume of the groove.
9. The bullet of claim 8 wherein: the rear portion of the sealing
band includes a rear wall; the front portion of the groove includes
a front wall; and the rear wall of the sealing band intersects the
front wall of the groove.
10. The bullet of claim 9 wherein: the groove has an arcuate
cross-sectional profile such that a surface of the groove is devoid
of edges; and a volume of the sealing band is greater than or equal
to the volume of the groove.
11. A round of ammunition for use in a 5.56 NATO-specification
chamber, comprising: a cartridge casing; and a bullet having a
casing engaging segment, a sealing band and a groove, wherein the
sealing band encircles the casing engaging segment, wherein the
casing engagement segment of the bullet is engaged within a bullet
receiving opening of the cartridge casing with a rear surface of
the sealing band abutting a front edge of the cartridge casing,
wherein the groove encircles the casing engagement segment, wherein
a rear portion of the sealing band intersects a front portion of
the groove, wherein a front face of the sealing band is
substantially flat, and wherein an angle of the front face of the
sealing band is approximately the same as an angle of a
neck-to-throat transition portion of the 5.56 NATO-specification
chamber.
12. The round of ammunition of claim 11 wherein: the groove has an
arcuate cross-sectional profile such that a surface of the groove
is devoid of edges; the rear portion of the sealing band includes a
rear wall; the front portion of the groove includes a front wall;
and the rear wall of the sealing band intersects the front wall of
the groove.
13. The round of ammunition of claim 11 wherein a volume of the
sealing band is greater than or equal to the volume of the
groove.
14. The round of ammunition of claim 11, further comprising: a
rifling leade mating segment extending from the casing engaging
segment forward of a front portion of the sealing band, wherein the
rifling leade mating segment has a frusto-conical shape tapering
from a first diameter at a first end portion thereof to a second
diameter at a second end portion thereof and wherein the first
diameter is greater than the second diameter; and an ogive portion
extending from the second end portion of the rifling leade mating
segment.
15. A round of ammunition configured for use in a chamber of a
firearm, wherein dimensions of a neck portion of the chamber and a
throat portion of the chamber are configured in accordance with
specifications of a firearms standards organization for the round
of ammunition, the round of ammunition comprising: a cartridge
casing configured in accordance with the specifications for the
round of ammunition, wherein the cartridge casing is configured
with dimensions allowing the cartridge casing to be operably
received within the neck portion of the chamber; and a bullet
having a casing engaging segment and a sealing band, wherein the
sealing band encircles the casing engaging segment, wherein the
bullet is engaged within a bullet receiving opening of the
cartridge casing with a rear surface of the sealing band abutting a
front edge of the cartridge casing, and wherein a maximum diameter
of the sealing band is greater than a minimum diameter of the
throat portion of the chamber.
16. The round of ammunition of claim 15 wherein: a front face of
the sealing band is substantially flat; and an angle of the front
face of the sealing band is approximately the same as an angle of a
neck-to-throat transition portion between the neck portion of the
chamber and the throat portion of the chamber.
17. The round of ammunition of claim 15, further comprising: a
groove encircling the casing engagement segment; wherein a rear
portion of the sealing band intersects a front portion of the
groove; and wherein the groove has an arcuate cross-sectional
profile such that a surface of the groove is devoid of edges.
18. The round of ammunition of claim 17 wherein: the rear portion
of the sealing band includes a rear wall; the front portion of the
groove includes a front wall; and the rear wall of the sealing band
intersects the front wall of the groove.
19. The round of ammunition of claim 17 wherein a volume of the
sealing band is greater than or equal to the volume of the
groove.
20. The round of ammunition of claim 15 further comprising: a
groove encircling the casing engagement segment; a rifling leade
mating segment extending from the casing engaging segment forward
of a front portion of the sealing band, wherein the rifling leade
mating segment has a frusto-conical shape tapering from a first
diameter at a first end portion thereof to a second diameter at a
second end portion thereof and wherein the first diameter is
greater than the second diameter; and an ogive portion extending
from the second end portion of the rifling leade mating segment;
wherein a rear portion of the sealing band intersects a front
portion of the groove; wherein a front face of the sealing band is
substantially flat; wherein the rear portion of the sealing band
includes a rear wall; wherein the front portion of the groove
includes a front wall; wherein the rear wall of the sealing band
intersects the front wall of the groove; and wherein an angle of
the front face of the sealing band is approximately the same as an
angle of a neck-to-throat transition portion between the neck
portion of the chamber and the throat portion of the chamber.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This continuation-in-part patent application claims priority
from co-pending United States Non-provisional patent application
having Ser. No. 13/066,780, filed Apr. 25, 2011, entitled "Subsonic
Small-Caliber Ammunition And Bullet Used In Same", having a common
applicant herewith and being incorporated herein in its entirety by
reference.
FIELD OF THE DISCLOSURE
[0002] The disclosures made herein relate generally to ammunition
for firearms and, more particularly, to subsonic ammunition for use
with semi and fully automatic weapons.
BACKGROUND
[0003] The projectile (i.e., bullet) from a fired weapon,
particularly a rifle, typically leaves the muzzle of the weapon at
a speed that is greater than the speed of sound, i.e. a muzzle
velocity of greater than approximately 1086 ft/sec. at sea level
under standard conditions of temperature and pressure. Such a speed
is referred to as being supersonic. Causing the bullet to achieve
supersonic speed is advantageous because the faster a projectile
travels, the flatter is its trajectory to its intended target.
Also, faster speeds of projectiles tend to reduce the effects of
lateral wind forces upon the path of the projectile to its intended
target.
[0004] Due to supersonic speed of a projectile enhancing its
accuracy of delivery to an intended target, it can be seen why it
is desirable for projectiles to have a supersonic muzzle velocity.
However, projectiles travelling at supersonic speeds generate an
audible sound during their free flight, which can undesirably be
used to locate the source of the weapon from which the projectile
was fired. Under certain circumstances of military operations
and/or police operations, it is desirable that the source of the
weapon firing a projectile not be identifiable by the sound
generated by the travelling projectile. Furthermore, for a
projectile of a given shape and mass, it is sometimes desirable for
muzzle velocity to be used in limiting the potential for the
projectile to strike a down-range object in the case with the
projectile misses or passes through its intended target.
[0005] In certain situations, one approach for mitigating adverse
concerns relating to supersonic muzzle velocity is to restrict the
speed of travel of the projectile to a subsonic speed (i.e., a
muzzle velocity of less than approximately 1086 ft/sec. at sea
level under standard conditions of temperature and pressure). In
doing so, the projectile does not generate an audible sound during
its free flight, thus limiting the potential for locating the
source of the projectile. Additionally, subsonic flight reduces the
distance that a projectile can travel, thereby limiting the
potential for the projectile to strike down-range objects.
[0006] In semi-automatic and fully automatic weapons, pressure
(i.e., energy) generated by firing of a round of ammunition serves
to energize the weapon's bolt actuation mechanism. As such,
implementing subsonic flight of a projectile in a manner that
reduces pressure within a weapon's barrel bore can result in there
being insufficient energy generated during combustion of the
ammunition to cycle the bolt in a semi-automatic or fully-automatic
weapon and/or to lock the bolt in its open position upon the firing
of the last round in the weapons' magazine. In some cases, gas
pressure provided at a gas port of a weapon can be increased to
suitable energizes a bolt-actuation mechanism of the weapon through
use of a sound suppressor to sufficient levels. However, removal of
the sound suppressor renders such weapon inoperable in its
semi-automatic and/or automatic modes of operation when such
pressure-deficient rounds of ammunition are used.
[0007] Accordingly, subsonic ammunition that is capable of
providing sufficient energy for cycling the bolt actuation
mechanism of a semi-automatic or fully automatic weapon without the
use of a sound suppressor is advantageous, desirable and
useful.
SUMMARY OF THE DISCLOSURE
[0008] Embodiments of the present invention are directed to bullets
and rounds of ammunition that are configured for use with
small-caliber semi-automatic and automatic weapons. More
specifically, small-caliber bullets and rounds of ammunition
configured in accordance with embodiments of the present invention
provide subsonic flight when discharged in a semi-automatic or
fully-automatic weapon and provide sufficient barrel bore pressure
characteristics for cycling a gas-energized bolt actuation
mechanism of such semi-automatic or fully-automatic weapon without
the use of a sound suppressor to augment gas pressure within the
barrel bore of the weapon. Ammunition configured in accordance with
the present invention is well suited for applications where
firepower is more of a consideration than is stealth. Accordingly,
embodiments of the present invention advantageously overcome one or
more shortcomings associated with some conventional small-caliber
subsonic rounds of ammunition.
[0009] In one embodiment of the present invention, a bullet
comprises a casing engaging segment defining a rear face of the
bullet, a sealing band encircling the casing engaging segment, and
a groove encircles the casing engagement segment at a position
between the sealing band and the rear face of the bullet. A rear
portion of the sealing band intersects a front portion of the
groove.
[0010] In another embodiment of the present invention, a round of
ammunition for use in a 5.56 NATO-specification chamber comprises a
cartridge casing and a bullet having a casing engaging segment, a
sealing band and a groove. The sealing band encircles the casing
engaging segment. The casing engagement segment of the bullet is
engaged within a bullet receiving opening of the cartridge casing
with a rear surface of the sealing band abutting a front edge of
the cartridge casing. The groove encircles the casing engagement
segment. A rear portion of the sealing band intersects a front
portion of the groove. A front face of the sealing band is
substantially flat. An angle of the front face of the sealing band
is approximately the same as an angle of a neck-to-throat
transition portion of the 5.56 NATO-specification chamber.
[0011] In another embodiment of the present invention, a round of
ammunition configured for use in a chamber of a firearm. Dimensions
of a neck portion of the chamber and a throat portion of the
chamber are configured in accordance with for the round of
ammunition. The round of ammunition comprises a cartridge casing
and a bullet having a casing engaging segment and a sealing band.
The cartridge casing is configured in accordance with the
specifications for the round of ammunition. The cartridge casing is
configured with dimensions allowing the cartridge casing to be
operably received within the neck portion of the chamber. The
sealing band encircles the casing engaging segment. The bullet is
engaged within a bullet receiving opening of the cartridge casing
with a rear surface of the sealing band abutting a front edge of
the cartridge casing. A maximum diameter of the sealing band is
greater than a minimum diameter of the throat portion of the
chamber.
[0012] These and other objects, embodiments, advantages and/or
distinctions of the present invention will become readily apparent
upon further review of the following specification, associated
drawings and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1A is a side view showing a round of ammunition
configured in accordance with a first embodiment of the present
invention.
[0014] FIG. 1B is a fragmentary cross-sectional view of the round
of ammunition of FIG. 1 showing orientation of elements thereof in
relation to a mating chamber of a rifle barrel in which the round
of ammunition is discharged.
[0015] FIG. 2 is a fragmentary cross-sectional view of the round of
ammunition of FIG. 1.
[0016] FIG. 3 is a fragmentary cross-sectional view of a round of
ammunition configured in accordance with a second embodiment of the
present invention positioned within a mating chamber of a rifle
barrel.
[0017] FIG. 4 is a side view showing a bullet of the round of
ammunition shown in FIG. 3.
[0018] FIG. 5 is a fragmentary cross-sectional view of the rifle
barrel shown in FIG. 3.
DETAILED DESCRIPTION OF THE DRAWING FIGURES
[0019] Referring to FIGS. 1A and 1B, a round of ammunition 100
configured in accordance with the present invention is shown. The
round of ammunition 100 is configured for use with small-caliber
semi-automatic and automatic weapons (e.g., a rifle).
Advantageously, the round of ammunition 100 is configured to
provide subsonic flight when discharged in a semi-automatic or
fully-automatic weapon and to provide sufficient gas pressure
characteristics for cycling a gas-energized bolt actuation
mechanism of such semi-automatic or fully-automatic weapon without
the use of a sound suppressor to augment gas pressure. In doing so,
the round of ammunition 100 advantageously overcomes a key
shortcoming associated with some conventional small-caliber
subsonic rounds of ammunition.
[0020] The round of ammunition 100 includes a small-caliber
cartridge casing 102 configured in accordance with specifications
of a firearms standards organization for a weapon. The
small-caliber cartridge casing 102 includes a first end portion 104
and a second end portion 106. Typically, a primer is mounted within
the second end portion 106 thereby making the second end portion
substantially closed. Preferably, but not necessarily, the
small-caliber cartridge casing 102 can be made a metal material
(e.g., brass) or from a polymeric material (e.g., nylon).
[0021] Standards for the shape and size of a cartridge for a
certain weapons of a given caliber have been established and
published by one or more various entities and/or organizations.
Examples of such entities and/or organizations (i.e., firearm
standards organizations) include, but are not limited to, Sporting
Arms and Ammunition Manufacturers Institute (SAAMI), Permanent
International Commission for Firearms Testing (CIP), and North
Atlantic Treaty Organization (i.e., NATO). SAAMI, CIP, and NATO are
examples of organisations that maintain standards that define
respective specifications for firearms and components thereof
(e.g., chamber specifications) and ammunition used therein. The
NATO standard to defines NATO specifications for firearms and
associated ammunition, the CIP standard to defines CIP
specifications for firearms and associated ammunition, and the
SAAMI standard defines SAAMI specifications for firearms and
associated ammunition.
[0022] A rifle of the M4/M16/AR15 family of carbine rifles is a
weapon that is capable of being operated in a semi-automatic mode
and/or fully-automatic mode and that utilizes barrel bore pressure
resulting from discharge of a round of ammunition to energize a
bolt actuation mechanism of the weapon. Thus, in one embodiment,
the round of ammunition 100 can be configured for use with a rifle
of the M4/M16/AR15 family of carbine rifles. However, in view of
the disclosures made herein, it is disclosed that a skilled person
will appreciate other weapons for which a round of ammunition
configured in accordance with the present invention will be useful
and that embodiments of the present invention are not unnecessarily
limited to use with any particular weapon (i.e., any particular
rifle, piston, or other type of small-caliber firearm).
[0023] The round of ammunition 100 has a bullet 108 (i.e., a
projectile) with a bearing surface portion 110 engaged within a
bullet receiving opening 112 of the cartridge casing 102. The
bullet receiving opening 112 is located at the first end portion
104 of the cartridge casing 102. Preferably, the bullet 108 is
engaged within the bullet receiving opening 112 of the cartridge
casing with a rear surface of the sealing band 121 abutting a front
edge of the cartridge casing 102. In this manner, a
propellant-receiving cavity 114 is formed within the cartridge
casing 102 between its first and second end portions 104, 106. An
ogive portion 116 (i.e., contoured tip portion) of the bullet 108
extends beyond the bullet receiving opening 112 and, optionally,
some of the bearing surface portion can also extend beyond the
bullet receiving opening 112.
[0024] As shown in FIGS. 1A, 1B, and 2, the bearing surface portion
110 of the bullet 108 has a sealing band 121 and sealing band
receiving groove 123 therein. In one implementation (shown), the
sealing band 121 is unitarily formed portion of the bullet 108. In
an alternate implementation, the sealing band 121 is separately
formed from a main body of the bullet 108 (i.e., portion comprising
the bearing surface 110 and ogive portion 116) from a metallic or
polymeric material and is subsequently attached to the main body of
the bullet 108 by a suitable means (e.g., mechanical interlock,
material-to-material bonding/welding, etc).
[0025] The sealing band 121 has an overall diameter that is greater
than a diameter of the chamber throat portion 125 of a firearm
chamber 127 and that is equal to or less than a diameter of a
chamber neck portion 129 of the of a firearm chamber 127 (e.g., the
minimum diameter of the chamber neck portion 129). Preferably, the
volume of the sealing band receiving groove 123 is of a sufficient
volume to receive therein all or a substantial portion of the
material defining the sealing band 121 (e.g., the volume of the
groove 123 is approximately equal to, equal to, or larger than a
volume of the material defining the sealing band 121). For example,
the sealing band receiving groove 123 can have a volume
substantially the same as the volume of the sealing band 121. In
this regard, when the bullet 108 is propelled past a chamber
transition 131, the sealing band 121 is deformed (e.g., swagged) by
contact with the chamber transition 131 and the sealing band
receiving groove 123 serves as a space in which all or a portion of
the material defining the sealing band 121 can become located
(e.g., urged into the sealing band receiving groove 123 through
contact with the chamber transition 131). The groove 123 preferably
also has an arcuate cross-sectional profile (e.g., semi-circular,
parabolic, concave, or the like) such that a surface of the groove
123 is devoid of edges.
[0026] A primary functionality of the sealing band 121 is to center
and gas seal the bullet 108 when used in an over-sized throat such
as the over-sized throat of the 5.56 NATO-specification chamber.
The throat of the 5.56 NATO-specification chamber and chambers of
firearms with a similar throat configurations are typically more
than 0.002'' larger in diameter than conventional throats. These
oversized throats allow gas to blow by the bullet in subsonic
rounds and may lead to under pressure rounds. Accordingly, the
sealing band 121 is designed to take up the space between the case
mouth and the front of the chamber where the chamber neck uses
typically a 45-degree angle to lead up to the chamber throat. In
this regard, a maximum diameter of the sealing band 121 is
preferably greater than a minimum diameter of the throat portion of
the chamber such that the sealing band at least partially fills a
space between the bullet 108 and a rifling groove bottom face of a
barrel mated to the chamber. When a bullet configured in accordance
with the present invention is intended for use in the 5.56
NATO-specification chamber (or suitably similarly configured
chamber), there are preferred specifications for a sealing band in
accordance with the present invention (e.g., the sealing band 121).
One example of such preferred specifications are shown in Table 1
below.
TABLE-US-00001 Parameter Value Leading Edge Angle (A) Approximately
the same as angle of chamber transition (e.g., about 45 degrees)
transition (e.g., about 45 degrees) Effective Length (B) About 75%
of horizontal distance (HD) between cartridge casing end face and
chamber transition (e.g., about 0.010) Trailing Edge Angle (C)
Approximately the same as angle of chamfer of cartridge casing
mouth Height (D) Difference between radius of chamber at throat and
radius of bullet at the bearing surface (e.g., preferably about
0.0019'' to about 0.0024'')
[0027] The effective length (B) of the sealing band 121 can be
increased nominally if the mouth of the cartridge casing 102 is
chamfered, which is commonly done to aid loading of bullets having
a flat base. Alternately, the cartridge casing can be trimmed to a
shorted length at the end face of its first end portion 104 from
the maximum NATO-specification dimension in order to allow a width
of the sealing band 121 to be increased.
[0028] The sealing band 121 can also serve to prevent the bullet
108 from being pushed back into the mouth of the cartridge casing
102 during loading into the firearm chamber 125. Because the
sealing band 121 is larger in diameter than the inside diameter of
the mouth of the cartridge casing 102, the sealing band 121 also
functions to. Thus, the sealing band 121 eliminates the need to do
any crimping (i.e., cannulating) of the cartridge casing 102, which
his advantageous as crimping of a cartridge casing can and
typically does causes damage to an engaged bullet. Still another
function of the sealing band 121 is to provide a fluid resistant
seal and the interface between the bullet 108 and the cartridge
casing 102.
[0029] Another potential function of the sealing band 121 relates
to providing a fluid-resistant seal between the bullet 108 and the
cartridge casing 102. In one aspect of this functionality, if a
trailing edge portion of the sealing band 121 and mating edge of
the cartridge casing mouth are designed with mating profiled,
(e.g., matched angles), the sealing band 121 can serve as an
effective fluid-resistant sealing structure that can preclude the
need for a `neck sealant` that is often used in a mouth of a
cartridge casing and/or or on the bearing surface portion of an
associated bullet. Omission of the neck sealant is advantageous, as
it is known to contaminate the barrel bore of a firearm from which
ammunition having such neck sealant is fired. Furthermore, in cases
where a neck sealant is used between the bullet 108 and the
cartridge casing 102, swagging of the sealing band 121 into the
sealing band receiving groove 123 will allow all or a significant
portion of the neck sealant to be swagged into the sealing band
receiving groove 123 and minimally contact the bore for a firearm
from which the bullet 108 is fired. Furthermore, if a sealant is
used only between the sealing band 121 and the mouth of the
cartridge casing 102, the contact area and therefore the amount of
neck sealant is going to be much less than in the conventional
approach that coats the full inside of the cartridge case neck and
corresponding length of the bullet with neck sealant.
[0030] A sealing band in accordance with the present invention can
be formed using any suitable technique. In one sealing band forming
technique, the sealing band is formed by placing a thin jacket
bullet formed conventionally it in a die, which is split at the
band location. The die is relieved with a ring that has the form of
the band. Once the bullet is placed in the die, pressure is applied
to cause the thin jacked to expand into this groove. In another
sealing band forming technique, the sealing band is formed by
electrochemical deposition of metal, guilding metal, copper, zinc.
In still another sealing band forming technique, the sealing band
is formed by injection of polymer (e.g., directly onto the
bullet.
[0031] Turning now to a discussion of bullet constructions, in
contrast to the monolithically formed bullet of FIGS. 1A, 1B, and
2, a bullet configured in accordance with an embodiment of the
present invention can have a core made of a first type of metal
disposed within a core-receiving cavity of a jacket made of a
second type of metal. A jacket configured in accordance with the
present invention can be made by the process of drawing metal
(e.g., a sheet of metal) into a given shape and the bearing surface
portion thereof can have a thickness of less than about 0.010''. In
a preferred embodiment, the bearing surface portion has a nominal
thickness between about 0.004'' and about 0.008''. Preferably, but
not necessarily, the jacket is made from a copper alloy including
about 90% copper (Cu) and up to about 10% zinc (Zn) and the core is
made from a metal having lead as its major constituent component.
In a preferred embodiment, the jacket is made from a copper alloy
having a minimum of about 2% zinc.
[0032] It is disclosed herein that, in an alternate embodiment, the
bullet 108 can have a core that is formed to provide the intended
exterior profile of the bullet 108 and have a plated jacket
provided over the core. In such an alternate embodiment, the core
is formed to have precise dimensions and profile of the bullet 108
shown in FIGS. 1 and 2. The core is then plated using a suitable
plating process to form the jacket to have a thickness that
provides the bullet with required/intended finished dimensions. For
example, the core can be plated to provide the bullet with an
outside diameter at the bearing surface portion that is of a
required/intended dimension.
[0033] As shown in FIG. 1A, the round of ammunition 100 has a
propellant 124 (e.g., powder) within the propellant-receiving
cavity 114. The propellant 124 can be a relatively slow burning
type propellant that provides a rapid peak in pressure build up
within the propellant-receiving cavity 114 and that maintains a
broader burn duration than relatively fast burning type
propellants. In one embodiment, the propellant 124 is configured by
a manufacturer thereof for being used as a medium caliber
ammunition propellant. One example of such a medium caliber
propellant suitable for use with rounds of ammunition configured in
accordance with the present invention has been offered from General
Dynamics Corporation under propellant no. XPR 47C1. In view of the
disclosures made herein, a skilled person will appreciate that
other propellants of suitable specification can be used in rounds
of ammunition configured in accordance with the present
invention.
[0034] During firing of the round of ammunition 100 within a
weapon, the propellant 124 in combination with the bullet 108
result in gas pressure characteristics and bullet-bore frictional
characteristics that provide for subsonic flight of the bullet 108
and for sufficient gas pressure within a barrel bore of the weapon
to cycling a gas-energized bolt actuation mechanism of the weapon.
For a given configuration of ammunition (e.g., 5.56 mm
NATO-specification ammunition), the bullet 108 will preferably be
heavier (e.g., by as much as 12 grains) than a bullet with a
standard thickness drawn-metal jacket (e.g., through use of a
relatively thin jacket and greater volume of the core in the case
of a jacketed projectile or through use of extra material in the
ogive portion 116). When this relatively heavy, bullet is subjected
to the heat and pressure of discharge of the propellant 108, the
relatively weight of the bullet 108 will result in enhanced
obturation of the bearing surface portion 110 of the bullet 108
within the barrel bore of the weapon such that sliding friction
between the bearing surface portion 110 and barrel bore will be
enhanced relative to a comparable bullet of conventional (i.e.,
prior art) construction.
[0035] In the case of a bullet configured in accordance with the
present invention having a jacketed construction, sliding friction
between the bore and the bullet will create heat in the jacket. The
core (e.g., lead) has relatively low heat conductivity and the
material of the jacket 120 (e.g., copper alloy) has relatively high
heat conductivity. Heat produced within the jacket will penetrate
the full thickness of the jacket within the time it takes for the
bullet to pass down a length of the barrel bore of the weapon. When
this heat reaches the core, the core serves as an effective
insulator thereby causing more heat to building the jacket and,
thus, soften the jacket further to provide for more sliding
friction. Roughly speaking, given identical frictional heating, a
jacket that is three times as thick as a thinner jacket will heat
up about one-third of the amount that the thinner jacket will heat
up. The friction coefficient of copper is a strong function of the
surface hardness and hardness is a strong function of temperature.
In this manner, the jacket being relatively thin further enhances
sliding friction between the bearing surface portion and the barrel
bore. In combination with these frictional and obturation
considerations of such a jacketed bullet, the propellant 124
discussed above provides gas pressure characteristics (e.g., peak
gas pressure, percent dwell around peak gas pressure, and average
gas pressures) within the barrel bore of the weapon to generate
sufficient gas-pressure derived energy at a gas port of the weapon
for cycling its bolt carrier when a round of ammunition configured
in accordance with the present invention is discharged. These gas
pressure characteristics in combination with the increased weight
of a bullet configured in accordance with an embodiment of the
present invention and frictional forces exerted on the bullet will
cause the bullet to decelerate from a supersonic speed (e.g., at a
barrel position where the gas port is located) to a subsonic speed
prior to exiting the barrel bore.
[0036] It is disclosed herein that the use of a layer of friction
reducing material on the bearing surface portion 110 of the bullet
108 can be used to influence gas pressure characteristics and/or
resulting velocity profile of the bullet 108. For example, as
disclosed above, molybdenum disulfide is one example of a
friction-reducing material composition to which the jacket 120 and
the shot (e.g., steel shot) can be exposed during such shot peening
for causing the exterior surface of the jacket 120 to become coated
with a layer of molybdenum disulfide. Coating the bearing surface
portion 110 with a layer of molybdenum disulfide or other suitable
friction reducing material composition can result in the bullet
exhibiting reduced initial friction in the barrel bore, with
diminishing effect as velocity of the bullet 108 increases (e.g.,
provides negligible effect with suitable velocity). Thus, its
application to the bearing surface portion 110 of the bullet 108
can result in lower initial gas pressure, which moderates and
broadens the initial gas pressure spike produced by combustion of
the propellant 120. In effect, such a layer of friction reducing
material can delay onset of heating of the jacket and thus
influence sliding friction as a function of time.
[0037] Referring now to FIGS. 3-5, various aspects of a round of
ammunition 201 configured in accordance with a second embodiment of
the present invention for use with a barrel 203 of a rifle (i.e., a
firearm) are shown. It is disclosed herein that the round of
ammunition can be constructed in a similar manner or the same
manner as is described above with respect to the round to
ammunition 100 discussed in reference to FIGS. 1A, 1B, and 2,
particularly in regard to implementation of a sealing band
configured in accordance with the present invention. In this
regard, the sealing band 221 and groove 223 of the bullet 200 can
be implemented and configured in a manner substantially or
identically to the sealing band 121 and groove 123 of the bullet
108 discussed above in reference to FIGS. 1A, 1B, and 2.
[0038] The round of ammunition 201 has a bullet 200 (i.e., a
projectile) engaged within a bullet receiving opening 205 of a
small-caliber cartridge casing 207 thereby forming a
propellant-receiving cavity 209 within the small-caliber cartridge
casing 207. A propellant 211 is provided within the
propellant-receiving cavity 209. The propellant 211 can be a
relatively slow burning type propellant that provides a rapid peak
in pressure build up within the propellant-receiving cavity 209 and
that maintains a broader burn duration than relatively fast burning
type propellants.
[0039] The bullet 200 includes a casing engaging segment 202, a
rifling leade mating segment 204, and a tip segment 206. The
rifling leade mating segment 204 has a frusto-conical shape
tapering from a first diameter at its first end portion 208 to a
second diameter at its second end portion 210. Frusto-conical
refers to a cone whose tip has been truncated by a plane parallel
to its base. The rifling leade mating segment 204 extends from a
first end portion 212 of the casing engaging segment 202. The tip
segment 206 extends from the second end portion 210 of the rifling
leade mating segment 204. The first diameter is greater than the
second diameter.
[0040] It is disclosed herein that the bullet 200 can be
constructed and/or manufactured in the same or similar manner as
the bullet 108. Accordingly, the bullet 200 can be constructed of a
drawn jacket with a core therein, can be constructed of a preformed
core having a plated jacket, or any other suitably configured
construction.
[0041] Preferably, but not necessarily, the tip segment 206
includes a barrel bore engaging portion 214 extending from the
second end portion 210 of the rifling leade mating segment 204. The
barrel bore engaging portion 214 has a substantially cylindrical
shape. A diameter of the barrel bore engaging portion 214 is
substantially the same as the second diameter. The tip segment can
also include a nose portion 215 having a substantially
hemi-spherical shape. However, a bullet configured in accordance
with the present invention is not limited to having a nose portion
of any particular shape.
[0042] A bullet in accordance with the present invention can be
configured as a 5.56 mm round of ammunition that is commonly used
in a rifle such as an M4 carbine. Such a round of ammunition can be
configured to have a second diameter that is about 0.2 inches. In
the case of such round of ammunition having a bullet configured in
accordance with the bullet 200 shown in FIGS. 4 and 5, the rifling
leade mating segment of the bullet of that round of ammunition can
have a conical taper CT, shown in FIG. 4, of about 2.4 degrees and
a rifling leade mating segment having a length of about 0.2 inches.
In an embodiment specific to a standard as provided by SAAMI, a
rifling leade segment can have a conical taper of about 3.2
degrees. Accordingly, in view of the disclosures made herein, a
skilled person will understand that the present invention is
directed to substantially or approximately mating the rifling leade
segment of a bullet to a rifling leade segment of a mating
firearm's chamber and that the present invention is not
unnecessarily limited to any particular conical taper of a rifling
leade.
[0043] As shown in FIGS. 3 and 5, a rifling leade region 216 of the
barrel 203 preferably has substantially the same profile and
dimensions as the bullet 200. Advantageously, such a mating
interface between the rifling leade mating segment 204 of the
bullet 200 and the rifling leade region 216 of the barrel 203
limits a rate at which combustion gas can escape from a chamber 218
of the barrel 203 into its rifled bore 220. For cartridges with
relatively low average and/or peak combustion gas pressure (e.g.,
subsonic cartridges), limiting the rate at which combustion gas can
escape from a chamber 218 of the barrel 203 into its rifled bore
220 prior to the bullet 200 entering the rifled bore 220 increases
a magnitude of combustion gas pressure in the chamber 218 and
subsequently in the rifled bore 220 as the bullet 200 travels down
the rifled bore 220. In this manner, a higher level of combustion
gas pressure is available to a gas-energized cartridge cycling
mechanism of the rifle for enabling operation in semi-automatic and
fully-automatic modes of operation without a sound suppressor. In
one such embodiment, a bullet/rifling leade interface precludes or
substantially inhibits combustion gas from escaping from the
chamber 218 of the barrel 203 into its rifled bore 220 prior to the
bullet 200 entering the rifled bore 220. In contrast, in prior art
implementations of bullet/rifling leade interfaces, the bullet has
had a non-mating profile with respect to the rifling leade such
that significant portions of combustion gas pressure is permitted
to escape into the rifled bore of the barrel prior to the bullet
entering the rifled bore of the barrel. As such, such prior art
bullet/rifling leade interfaces have lead to unreliable if not
unacceptable firearm performance in semi-automatic and
fully-automatic modes of operation without a sound suppressor.
[0044] It is disclosed herein that configuring a round of
ammunition in accordance with the present invention can include
manipulating ammunition-specific parameters including, but not
limited to, jacket thickness, jacket material composition, jacket
hardness, bearing surface length, core material composition,
propellant type, propellant quantity, and jacket surface coating
presence/type. All or a portion of these ammunition-specific
parameters can be manipulated in view of weapon-specific parameters
including, but not limited to, barrel bore diameter, barrel bore
length, gas port position/size, required bolt actuation mechanism
energy, barrel bore material, etc. In view of the disclosures made
herein, a skilled person will be able to specify
ammunition-specific parameters for ammunition configured in
accordance with the present invention for a particular
configuration of weapon (e.g., a rifle) by experience and/or with
minimal experimentation.
[0045] In the preceding detailed description, reference has been
made to the accompanying drawings that form a part hereof, and in
which are shown by way of illustration specific embodiments in
which the present invention may be practiced. These embodiments,
and certain variants thereof, have been described in sufficient
detail to enable those skilled in the art to practice embodiments
of the present invention. It is to be understood that other
suitable embodiments may be utilized and that logical, mechanical,
chemical and electrical changes may be made without departing from
the spirit or scope of such inventive disclosures. To avoid
unnecessary detail, the description omits certain information known
to those skilled in the art. The preceding detailed description is,
therefore, not intended to be limited to the specific forms set
forth herein, but on the contrary, it is intended to cover such
alternatives, modifications, and equivalents, as can be reasonably
included within the spirit and scope of the appended claims.
* * * * *