[0001] The present invention relates to round of subsonic ammunition and to a method of
manufacturing the same.
[0002] Subsonic ammunition is widely known in the art, see for instance "Gesamtjahres Katalog
88/89", FRANKONIA, WURZBURG, 1988/89: The specific construction thereof is not described.
[0003] US A-5279787, which is the closest state of the art, describes a high density projectile
manufactured by combining metal powders of different melting points. The metal powders
can include tungsten and lead powders. The powders are formed into a core composition
received within a jacket. The core is formed as a single element and is made by powder
metallurgy techniques well known in the art (compacting and heating) or by a casting
process. In a casting process, the low melting point metal is heated into the molten
state and thereafter mixed with the powder having the higher melting point, or the
low melting point metal is heated to the molten state, cooled to become pasty, and
thereafter the high melting point metal powders are introduced.
[0004] This invention relates to ammunition wherein the projectile thereof has a muzzle
velocity of less than the speed of sound, i.e. subsonic, as the projectile leaves
the weapon and during its free flight to a target. Particularly the invention relates
to subsonic ammunition for small-bore weapons, i.e. weapons of 127 cm (50 caliber)
or smaller bore and which operate in a semi-automatic or automatic mode. As used herein,
the terms "weapon" and "gun" are at times used interchangeably and are to be deemed
synonymous unless otherwise indicated or obvious from the context of their use.
[0005] Most commonly, the projectile fired from a weapon, particularly a rifle, leaves the
muzzle of the weapon at a speed that is greater than subsonic speed, i.e. at a muzzle
velocity of greater than approximately 331 m/s (1086 ft/sec). at sea level under standard
conditions of temperature and pressure. The faster a projectile travels, the flatter
is its trajectory to its target. Also faster speeds of projectiles tend to reduce
the effects of lateral wind forces upon the path of the projectile to its target.
Therefore, for accuracy of delivery of the projectile to a desired target, commonly
it has been the practice to maximize the quantity of powder used to project a given
weight projectile to its target consistent with the permissible pressure for a given
weapon. Minimization of projectile weight also has been employed to provide greater
projectile velocity. Supersonic muzzle velocities, therefore, are the norm for most
small-bore rifles. Pistols, on the other hand, commonly exhibit subsonic muzzle velocities.
In the prior art, it is also common to employ noise and/or flash suppressors on either
rifles or pistols. These devices function to reduce the sound associated with the
explosion of the gun powder in the cartridge and/or the rush of gases from the muzzle
of the weapon, but, standing alone, suppressors are neither designed for nor intended
to reduce a super sonic velocity bullet fired from a gun to a subsonic velocity, nor
do suppressors materially affect noise generated by the movement of a projectile through
air.
[0006] Projectiles traveling at supersonic speeds frequently generate an audible sound during
their free flight to the target, a major source of which is wobble (yaw) of the projectile
during flight. This sound, and/or the sound generated by the projectile breaking the
sound barrier, can 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 traveling projectile. Restricting the velocity of the
projectile to a subsonic speed provides only a partial solution to this problem.
[0007] A round of ammunition (at times synonymously termed a "bullet" or a "cartridge")
normally includes a case which includes a primer, a quantity of powder contained within
the case, and a projectile held in the open end of the case. Upon the striking of
the primer by the firing pin of the weapon there is generated a flame which serves
to ignite the powder within the case, generating gases which expand and propel the
projectile from the muzzle of the weapon. Normally, the case is geometrically shaped
and sized to be contained within the chamber of the weapon, and the projectile is
of a diametral dimension which allows it to fit in the breech end of the barrel, and
to eventually pass through the barrel upon firing of the round. For many rifles, for
example, it is common to make the case of the round of ammunition of a size which
will provide for the maximumization of the force with which the projectile is propelled
from the weapon to the target. Thus, it is common, for a round for a given caliber
weapon, to employ a case which will contain a maximum amount of powder, hence the
case has a large diameter relative to the diameter of the projectile employed. Over
time, these cases have become the "standard" case for a particular caliber weapon
and weapons of this caliber are chambered to accept this standard case. Standards
for the shape and size of a cartridge for a given weapon, e.g. a rifle, of a given
caliber are established and published by Sporting Arms and Ammunition Manufacturers
Institute (SAMI).
[0008] In the many instances where the standard cartridge case is of a diameter which is
substantially larger than the diameter of the bore of the weapon, that end of the
case which receives and holds the projectile of the cartridge is "necked down" to
a diameter suitable to engage and hold the projectile in the case. For example, the
outer diameter of the case for a 5.56 mm cartridge commonly is approximately 9,14
mm (.360 inch), and the outer diameter of the projectile thereof is 5,69 mm (.224
inch). In any event, any portion of the projectile that projects from the end of the
case is received within the breech end of the bore of the weapon. In this situation,
the circular shoulder developed on the case by the necking-down operation serves as
a point of reference for the insertion of the cartridge in the chamber of the weapon.
Specifically, the chamber of the weapon is sized and shaped such that, when the cartridge
is fully and properly inserted into the chamber, at least the juncture of the necked-down
length of the case with the circular base of the shoulder engages the breech end of
the barrel. With the cartridge in this position within the chamber, that portion of
the projectile which projects outwardly from the end of the case is disposed within
the bore of the weapon. Through adjustment of the length of that portion of the projectile
which extends from the end of the case, it is possible to select the distance by which
the projectile extends into the bore of the weapon. The degree of this adjustment,
however, is limited to that amount which will not cause the overall length of the
cartridge to be unacceptably outside the SAMI specifications for the cartridge when
used in a semi-automatic or automatic weapon.
[0009] Heretofore, it has been proposed to produce subsonic ammunition which comprises the
"standard" case and projectile for a given weapon, e.g. a rifle, and to merely reduce
the quantity of powder used to propel the projectile, to that volume of powder which
provides only sufficient energy to propel the projectile at a subsonic muzzle velocity.
The round of ammunition thus produced is like a standard round of ammunition for its
intended weapon, but it is only about 50% or less filled with powder, leaving a substantial
portion of the interior volume of the case void of powder. This type of subsonic ammunition
is commonly fired as a "single shot" round and is not capable of producing the energy
required to operate the bolt of a semi-automatic or automatic weapon.
[0010] A further major problem with this prior practice for the manufacture of subsonic
ammunition relates to the reduced volume of powder within the case of the cartridge
and the void volume within the case. Specifically, when the weapon is pointed (aimed)
at a downward angle, relative to the horizontal, the powder within the case moves
toward the leading end of the case and adjacent to that end of the projectile which
is inserted into the case. This serves to form an air gap between the primer and the
powder so that when the primer is struck by the firing pin, there is a finite time
before the flame from the primer reaches and ignites the powder within the leading
end of the case, and a finite time elapsing before the burning powder generates sufficient
gases to propel the projectile from the weapon. Conversely, if the weapon is aimed
upwardly, relative to the horizontal, the powder within the case moves toward the
primer so that upon the firing of the primer there is instantaneous ignition of the
powder and relatively quicker build up of the gases which propel the projectile from
the weapon. At intermediate angles of aiming of the weapon, relative to the horizontal,
there are corresponding intermediate delays in the time required for the projectile
to be propelled from the weapon after the firing pin has struck the primer. These
degrees of delay are extremely detrimental to the accuracy of delivery of the projectile
to an intended target. In some circumstances, the delays in "firing" or "hang-fires"
of the weapon have been sufficiently long as to deceive the shooter firing the weapon
into believing that they have experienced a misfire. Suspecting a misfire, the shooter
may open the bolt of the weapon to eject the suspected faulty round, whereupon the
round may explode with obvious serious endangerment to the shooter.
[0011] In accordance with another aspect of the prior art subsonic ammunition, it has been
the practice to use fast-burning powders, e.g. pistol powders. These powders exacerbate
the problem of erratic propulsion of a projectile from the weapon by reason of the
rapid build up of pressure within the case and the rapid fall-off of the pressure
once the projectile leaves the case. As a consequence, the prior art subsonic ammunition
fails to provide the energy needed to operate the bolt in a semi-automatic or automatic
weapon and/or to lock the bolt in an open position upon the firing of the last round
in the magazine.
[0012] It is known in the art that the energy required to operate the bolt of a weapon intended
to be fired in a semi-automatic or automatic mode involves the build-up of gas pressure
within the barrel of the weapon to the location of a gas exit port near the muzzle
of the barrel, such gas pressure being adequate to operate the bolt mechanism.
[0013] It is therefore an object of the present invention to provide an improved round of
subsonic ammunition for small-bore weapons.
[0014] It is another object to provide ammunition for a small-bore weapon and which is consistently
subsonic in velocity from round to round of the ammunition.
[0015] It is another object to provide subsonic ammunition which will effectively operate
the bolt of an automatic or semi-automatic weapon.
[0016] It is another object to provide a method for the manufacture of subsonic ammunition
for a small-bore weapon, particularly a semi-automatic or automatic weapon.
[0017] It is another object to provide a novel projectile for subsonic ammunition.
[0018] It is another object to provide a method for the manufacture of a projectile for
subsonic ammunition.
[0019] Other objects and advantages of the present invention will be recognized from the
description contained herein, including the claims and the drawings.
[0020] These objects are met by the features of claims 1 and 10.
[0021] In accordance with one aspect of the present invention there is provided a round
of ammunition for a small-bore weapon wherein the projectile of the round exits the
muzzle of the weapon barrel at a subsonic velocity and which continues its flight
path to a target at less than a sonic velocity without generating identifiable sound
associated with the flight of the projectile through air. Additionally, the ammunition
provides the energy required to operate the bolt of a weapon fired in the semi-automatic
or automatic mode. To this end, the present inventor has discovered that by means
of a unique projectile combined with a powder of selected burn rate, in a standard
case, there can be attained the objectives of subsonic velocity of the projectile,
development of the energy required to operate the bolt of a weapon fired in the semi-automatic
or automatic mode and elimination of substantially all sound generated by the projectile
during its free flight through air.
[0022] In accordance with one aspect of the present invention, the projectile of the present
invention is maximized in weight for a given length of a projectile for a given caliber
weapon. This action preferably takes the form of forming the projectile from high-density
metal powders, maximizing the length of the projectile, consistent with intended caliber
of the projectile and the twist of the lands in the barrel of the weapon for which
the ammunition is intended, and minimizing any variation in the density of the projectile
in any given plane normal to the length of the projectile and in a direction radially
outward from the longitudinal centerline (spin axis) of the projectile. A benefit
from the use of this unique projectile is that when the projectile is inserted in
the open end of a standard case for a weapon of the intended caliber, the projectile
occupies a substantial portion of the internal volume of the case, thereby diminishing
that portion of the internal volume of the case which is available to receive gun
powder, thereby permitting the case to be filled to a higher percentage of its void
volume. Further, in one aspect of the present invention, the inventor has found that
use of a gun powder of medium burn rate provides gas generation at a rate and of a
volume which, in combination with the heavy projectile, propels the projectile at
a subsonic velocity while generating the energy needed to operate the bolt of a weapon
fired in the semi-automatic or automatic mode.
[0023] In one embodiment of the present invention, maximization of the projectile weight
and radial uniformity of density are promoted through the use of a mixture of metal
powders that are cold-compacted in a die to produce multiple discrete core elements
which are ultimately combined to define a core for the projectile. Specifically, in
the process of die-forming of a mixture of metal powders, of the type employed in
the present invention at a high pressure, e.g. about 3.45 × 10
-8 Pa (50,000 psi), the density of the product is greater adjacent the opposite ends
of the formed product than in the central portion of the length dimension of the product.
The present inventor utilizes this feature to produce multiple individual elements
of a core and thereafter combines these elements to provide a functionally unitary
core which has an overall density (weight) which is greater than is possible to obtain
when the core is formed as a single unit. In one aspect of the invention, each of
the core elements is formed to its own specific geometry for purposes of the desired
combining of the elements into a core for the projectile.
[0024] The combining of the multiple core elements, in one embodiment, is preferably accomplished
by selective insertion of the core portions into a soft metal jacket contained in
a die cavity. The jacket employed preferably is cup-shaped, having a closed end and
an open end. The jacket commonly is formed by deep drawing a metal blank so that the
wall thickness of the jacket decreases from a maximum adjacent the closed end thereof
to a minimum thickness adjacent the open end of the jacket. The change in wall thickness
of the jacket along its length is of primary importance in approximately that half
of the length of the jacket extending from the closed end to the midpoint of the length
of the jacket. Within this half of the length of the jacket, the wall thickness varies
sufficiently as precludes the full insertion, without the application of substantial
force, into this half of the jacket of a core element which is diametrally dimensioned
to equal the internal diameter of the other half of the jacket. Thus, in the present
invention, the inventor forms a first core element which is cylindrical in geometry
and which has a diameter that permits the insertion of the first core element into
the interior of that half of the jacket nearest the closed end of the jacket. A second
core element is formed which is cylindrical in geometry and which has a diameter that
is larger than the diameter of the first core element and which permits the second
core element to fit snugly within that half of the jacket length nearest the open
end thereof. In a preferred embodiment, the combined lengths of the first and second
core elements is slightly less than the total interior length of the jacket so that
a portion of the jacket wall adjacent the open end thereof is available for deformation
radially inwardly of the jacket to at least partially close the open end of the jacket
and capture the core elements within the jacket.
Figure 1 is a representation of a rifle cartridge, partly sectioned, depicting various
of the features of the present invention;
Figure 2 is an exploded view of the components of one embodiment of a core element
employed in the projectile of the present invention;
Figure 3 is a side elevation view, in section, of the projectile components depicted
in Figure 2 as partially assembled into a projectile;
Figure 4 is a side elevation view, in section of the projectile components depicted
in Figure 2 as fully assembled into a projectile;
Figure 5 is a side elevation view, in section, of one embodiment of a jacket employed
in the projectile of the present invention;
Figure 6 is an enlarged view of a portion of the jacket depicted in Figure 5, and
taken generally along the line A-A of Figure 5;
Figure 7 is a representation of a pistol cartridge, partly sectioned, depicting various
of the features of the present invention; and
Figure 8 is flow chart depicting one embodiment of the method of the present invention.
[0025] In the present invention, a "heavy" projectile is defined as a projectile having
a density greater than lead, e.g. about 12 or more g/cm
3, and a total weight of at least 8,68 g (134 grains), for a 5.56 mm cartridge or a
proportional weight projectile for a different size cartridge, such as a projectile
of 16,20 g (250 grains) for a 7,8 mm (.308 caliber) cartridge and of a density greater
than lead. As noted, a preferred powder exhibits a medium burning rate. For the present
invention, a "medium burning" gun powder is a gun powder that has a burn rate substantially
equal to the burn rate of Hodgdon 380® gun powder. Each of the elements of the present
invention is selected in combination with the other elements to obtain consistency
of subsonic velocity from round to round of the ammunition and provide the energy
required for operating the bolt of a semi-automatic or automatic weapon without the
projectile exceeding subsonic velocity, while also substantially eliminating any sound
generation associated with the free flight of the projectile through air.
[0026] One embodiment of the present invention is depicted in the several Figures, and includes
a round of subsonic ammunition 10 which includes a generally tubular case 12 having
a closed end 14 and an open end 16. Within the closed end 14 there is provided a flame
port 18 and a primer 20 contiguous to the flame port. The open end of the case includes
a necked down, i.e. reduced diameter, portion 22 that is internally sized to receive
therein a projectile 24 having a multipart core 25. Within the case, and between the
closed end and the projectile, there is defined a cavity 26 within which there is
loaded gun powder 28. The geometry of the case is chosen to conform with industry
standards for a given caliber cartridge, e.g. 5,66 mm (.223 caliber) (equivalent to
5.56 mm which is designed to be fired from M-16 automatic weapon, for example). These
standards establish the outer diameter of the case, the overall length of the case,
the length of the case from the closed end to the beginning of the shoulder 30 formed
between the necked down portion 22 and the body 32 of the case, and the internal diameter
of the open end of case, among other aspects of the cartridge. Further, the cartridge
must conform to the overall length (OAL) industry standard for the given caliber cartridge.
The OAL 34 of the cartridge is measured from end to end of the cartridge, including
the projectile. This OAL of a round of ammunition is critical to the successful feeding
of the cartridge from a magazine into the firing chamber of a semi-automatic or automatic
gun.
[0027] For purposes of the present description of the invention, a 5.56 mm cartridge is
discussed, but it will be recognized that the present invention encompasses other
sizes (calibers) of cartridges, particularly 7,8 mm (.308 caliber) cartridges.
[0028] In accordance with one aspect of the present invention, the projectile 24 of the
present invention is of maximized weight for a given caliber. To accomplish this desired
aspect, the present inventor provides a projectile which preferably is formed from
a blended mixture of a heavy metal powder, such as tungsten powder, and a lighter
weight metal powder, such as lead. A portion of the blended powders is cold-compacted
in a die into a first solid cylinder 40. As depicted in Figure 2, this first cylinder
exhibits greater density adjacent each of its opposite ends 42 and 44, this density
gradation along the length of the cylinder being achieved by pressing the powders
in the die having a cylindrical cavity at a pressure of at least about 2,76 × 10
8 Pa (40,000 psi) and preferably at a pressure of about 3,45 × 10
8 Pa (50,000 psi). In order to take advantage of this noted feature of the cold-compacted
solid cylinder, the present inventor forms the core 25 of the projectile from at least
two individually cold-compacted solid cylinders. Thus, a further portion of the blended
powders is likewise cold-compacted into a second solid cylinder 46 which also exhibits
greater density adjacent each of its opposite ends 48 and 50. In accordance with one
aspect of the present invention, these greater densities adjacent the ends of the
first and second solid cylinders 40 and 46 contribute significantly to the overall
density of each of the solid cylinders, hence to the overall density of the projectile
which is produced from these cylinders.
[0029] It is to be recognized that in a given weapon having a rifled barrel, a projectile
fired from the weapon will be spinning about its longitudinal centerline at a rate
which is a function of the twist of the lands inside the bore of the weapon barrel.
By way of example, M-16 military rifle employs a one-in-seven twist, meaning that
each land completes a full turn within each 17,78 cm (seven inches) of barrel length.
Thus, a projectile fired from this weapon at a velocity of 320 m/s (1050 fps) will
be spinning at a rate of 108,000 rpm. At this rate of spin, any deviation of the center
of gravity of the projectile from its longitudinal centerline (i.e. its spin axis)
will result in the projectile exhibiting wobble (yaw) during its free flight to a
target, hence generation of sound during flight. The present inventor found that in
the course of forming the projectile of the present invention, absolute coincidence
of the center of gravity of the projectile with its longitudinal centerline (spin
axis) is not attainable for projectile that exceed a certain maximum length so that
there exists a maximum length of a projectile for a given caliber projectile fired
from a given weapon, which will remain sufficiently stable in free flight as prevents
the projectile from generating audible sound while in flight. Specifically, it has
been found that a projectile of a length greater than about 28,45 mm (1.12 inch) fired
from an M-16 military rifle becomes unstable in flight to the extent that the projectile
generates audible sound. This length factor, plus the limitation imposed by the caliber
of the projectile, produces a limit on the permissible length of a projectile for
a given weapon, thereby limiting the permissible volume of a projectile for the weapon.
Accordingly, in the present invention, the overall density of the projectile is important
in maximizing the weight of the projectile, but also of importance is the attainment
of maximum uniformity of density of the projectile in a direction radially outward
from the longitudinal centerline of the projectile, taken in any given plane normal
to the longitudinal centerline of the projectile. The absolute density of the projectile
of the present invention may vary from plane-to-plane, but, radially about the centerline
of the projectile, is substantially uniform in any given plane.
[0030] In the manufacture of the first and second solid cylinders 40 and 46, preferably
each cylinder is formed from tungsten metal powder of about -2 and + 0,21 mm (-10
and +70 mesh)such as the C and M series available from Osram Sylvania of Morristown,
NJ, and lead powder having a size of about 0,044 mm (a mesh of about 325), such as
that available from Atlantic Engineers of Bergenfield, NJ. In the mixture, the tungsten
powder represents between about 40% and 75%, by weight of the mixture, with the remaining
weight of the mixture being lead powder. Other powder mixtures may be employed but
at the possible expense of attaining less than maximization of the density of the
projectile. Further, a third, or more, powder(s) may be included in the mixture for
various purposes such as increasing or decreasing the hardness or frangibility of
the projectile. The mixture of these powders is blended and a portion of the blended
powders is introduced into the cavity of a die having a cylindrical die cavity. In
the die, the mixture of powders is cold-compacted at a pressure of at least about
2.76 × 10
8 Pa (40,000 psi) and preferably at a pressure of about 3.45 × 10
8 Pa (50,000 psi). Under these pressing conditions, the powder mixture is densified
and formed into a hard, self-supporting, solid cylinder. The density of the cylinder,
however, is greater adjacent its opposite ends than in the central portion of the
cylinder between its opposite ends. As noted, to maximize the density of the projectile
core of the cartridge of the present invention, the core is formed from at least two
solid cylinders which have been individually formed by cold-compaction in a die. By
this means, each of the solid cylinders exhibits two areas of maximized density, ie.,
the area adjacent each of the opposite ends of the cylinder. The resulting core includes
four areas of maximized density, thereby resulting in an overall maximization of the
density of the core.
[0031] To form the projectile, the first and second solid cylinders are inserted into a
cup-shaped jacket 52 which is formed by deep drawing of a metal blank. The metal of
the jacket is one which exhibits lubricity properties between the projectile and the
interior of the gun barrel when the projectile is traveling along the barrel during
firing of the weapon. A preferred metal is copper. After being formed, the jacket
includes a closed end 54, an open end 56 and a longitudinal centerline 64.
[0032] Referring to Figures 5 and 6, deep drawing of a metal blank into a jacket produces
a jacket which possesses a wall section adjacent the closed end 54 of the jacket which
progresses from a relatively thick wall at "A" contiguous to the closed end of the
jacket to a less thick wall at "B", the approximate midpoint 58 between the opposite
ends of the jacket. The wall thickness "C" of the jacket between the approximate midpoint
of the length of the jacket and the open end of the jacket normally does not vary
significantly for purposes of the present invention.
[0033] In a preferred embodiment, the first solid cylinder 40 is formed to an external diameter,
d
1, which is substantially equal to, but not greater than the internal diameter of the
jacket adjacent the closed end thereof so that this cylinder can be inserted into
the jacket to a location contiguous the closed end of the jacket. The second solid
cylinder 46 is formed to a second diameter, d
2, which is substantially equal to, but not greater than, the internal diameter of
the jacket in the region between the length mid-point and the open end of the jacket.
Preferably, the cylinders are substantially equal in length, but it is permissible
for one of the cylinders to be slightly longer than the other cylinder if desired.
The combined lengths of these two solid cylinders determines the overall length of
a core 51 of the projectile. As noted, at least two solid cylinders are employed per
each projectile core. More than two cylinders per core may be employed, but more than
two cylinders may not contribute sufficiently greater weight to the projectile as
justifies the cost associated with producing and processing the additional cylinders.
[0034] In one embodiment, the jacket is placed in an encompassing die and the first cylinder
is inserted into the jacket, followed by insertion of the second cylinder into the
jacket in tandem within the first cylinder. Thereupon, the cylinders are placed under
high pressure, e.g. greater than about 2,76 × 10
8 Pa (40,000 psi) and preferably about 3,45 × 10
8 Pa (50,000 psi), and deformed, as by means of a die punch aligned with and parallel
to the longitudinal centerline 64 of the jacket, to cause the two cylinders to fill
a selected portion of the internal volume of the jacket, leaving an unfilled portion
60 of the jacket. The jacket wall section 68 distal of the second solid cylinder is
subsequently folded inwardly toward the longitudinal centerline 64 of the jacket to
at least partially close the open end of the jacket and to capture the first and second
cylinders within the jacket. In a preferred embodiment, the end 52 of the jacket is
not fully closed by the inwardly folded wall of the jacket, thereby leaving a circular
opening 66 defined in the end 56 of the jacket which becomes filled with a portion
of the powder mixture of the core during the course of the swaging operation. This
design feature serves to enhance the dispersion of the projectile upon the projectile
striking a target as is well known in the art.
[0035] Notably, even though the density of each cylinder is nonuniform from end-to-end of
the cylinder, in any given plane of the cylinder taken normal to the longitudinal
centerline of the cylinder, the density of each cylinder is uniform in a direction
radially outward from the longitudinal centerline of the cylinder. That is, within
a given plane the density is uniform about the spin axis of the projectile. This aspect
of each cylinder is important in establishing the center of gravity of the projectile
substantially coincident with the longitudinal centerline of the projectile, (i.e.,
with the spin axis of the projectile) and thereby reducing the likelihood of the projectile
exhibiting yaw during its free flight to a target. In this regard, it is also to be
noted that in the process of inserting the cylinders into the jacket, the cylinders
are not only sized to fit snugly within the jacket in stacked relationship, but further
their respective longitudinal axes are aligned coincidently. To this end, the compressive
force applied to the tandemly stacked cylinders in the jacket is aligned with and
parallel to the longitudinal centerline of the jacket, hence also aligned with and
parallel to the longitudinal centerline of the stacked cylinders. By this means, it
is believed that deformation of the cylinders as necessary to cause the cylinders
to conform to the internal dimensions of the jacket is limited principally to the
radial extremities of the cylinder, leaving the vast bulk of each cylinder radially
unchanged, hence retaining the radial uniformity of the density of each cylinder substantially
intact. It also is believed that the high pressure employed in forcing the cylinders
to conform to the internal dimensions of the jacket tends to reconstitute a substantial
portion of any bonding between adjacent powder particles which is disrupted in the
course of deformation of the cylinders as they are caused to conform to the jacket
interior. These factors are further believed to significantly contribute to the observed
absence of sound generation by the projectile during its free flight to a target by
reason of the attained degree of coincidence of the center of gravity and the longitudinal
centerline of the projectile of the present invention.
[0036] Cartridges for a 5.56 mm weapon operating in the semi-automatic mode were fabricated
and fired to test the velocity of the projectile from each cartridge and the ability
of the cartridges to develop sufficient energy to consistently operate the bolt of
the weapon. In the manufacture of these cartridges, there was chosen a standard case
of brass metal.
[0037] For each of these cartridges, there was provided a projectile comprising a copper
metal jacket which has been deep drawn to a length of 27,94 mm (1.100 inch). The wall
thickness of the jacket adjacent the closed end thereof ("A") provided an internal
diameter of about 4,75 mm (0.187 inch)at this location. The wall thickness of the
jacket tapered from the closed end thereof toward the midpoint of the length of the
jacket to a wall thickness ("B") providing an internal diameter of 4,83 mm (0.190
inch)at this location. The wall thickness of the jacket from the midpoint to the open
end thereof did not vary materially for present purposes. The internal diameter of
the jacket at its open end was 4,83 mm (0.190 inch).
[0038] To form a core for the projectile, there was formed a first solid cylinder having
an outer diameter of 4,75 mm (0.187 inch) employing a mixture of 60%, by weight, tungsten
powder and 40%, by weight, of lead powder. The tungsten powder was of -2 + 0,21 mm
(-10 + 70 mesh). The lead powder was of 0,044 mm (325 mesh). These powders were blended
and a portion thereof introduced into a die having a cylindrical cavity. Within the
die, the powder mixture was subjected to cold-compaction (at ambient temperature)
under a pressure of 3,45 × 10
8 Pa (50,000 psi). The overall density of this first cylinder was in excess of 14 g/cm
3. A second solid cylinder having an external diameter of 4,83 mm (0.190 inch) was
formed in like manner as the first cylinder. This second cylinder exhibited an overall
density in excess of 14 g/cm
3.
[0039] The copper jacket of the projectile was inserted into a die having a cylindrical
internal cavity of an internal diameter of 5,69 mm (0.224 inch). The first solid cylinder
was inserted into the jacket through the open end of the jacket disposed in the die,
followed by insertion of the second cylinder into the jacket through the open end
thereof, so that these cylinders were stacked in tandem within the jacket. A die punch
was inserted into the die to engage and apply pressure to the stacked cylinders in
a direction aligned with and parallel to the longitudinal centerline of the jacket.
A pressure of 3,45 × 10
8 Pa (50,000 psi) was applied to the stacked cylinders. This pressure deformed the
first cylinder, causing this cylinder to conform to and fill that portion of the internal
cavity of the die adjacent the closed end thereof. Further, the applied pressure served
to consolidate the two cylinders into a functionally unitary core having an overall
density in excess of 14 g/cm
3 and an overall length of 26,42 mm (1.040 inch). Some length increase of the jacket
occurred.
[0040] After compression of the cylinders, there remained a length of about 0,76 mm (0.030
inch)of the jacket wall that extended distally of the core. This wall length was thereafter
folded inwardly over the distal end of the core, as by swaging, to partially cover
the distal end of the core and to aid in retention of the cylinders within the jacket.
In this test, the infolded jacket wall did not fully cover the distal end of the core,
leaving a circular area of uncovered core that was substantially concentric with the
centerline of the jacket and filled with a portion of the powder mixture. This area
served as aid to disintegration of the jacket and/or core upon impact with a target
in a manner that is well known in the art. The overall weight of each of the projectiles
tested was 8,68 g (134 grains).
[0041] The case of these cartridges was loaded with a Federal 205 Match primer in the closed
end thereof and with 0,73 g (11.2 grains) of H 380®, a spherical-particle gun powder
from Hodgdon Powder Co., followed by insertion of a projectile within the open end
of the case, thereby closing the open end and providing an OAL of the cartridge of
5,74 cm (2.260 inch. The powder filled approximately 65% of the cavity defined in
the case between the primer and the projectile. This powder exhibited a medium burn
rate. In addition to its other properties, this powder exhibits consistent burn properties
at temperatures of between about -17,8°C (0°F) and about 51,67°C (125° F).
[0042] Like cartridges were prepared employing other gun powders, having either a slower
and faster burn rate than the H-380® powder. These latter cartridges, along with the
cartridges which included the H 380® powder, were fired from an M-16 (5.56 mm) weapon
operating in the semi-automatic mode. The barrel length of the weapon was 36,83 cm
(14.5 inches). At least ten rounds of cartridges made from each of these powders were
fired. The muzzle velocities of the several cartridges were monitored employing standard
chronograph techniques. Only the cartridges made with the slowing burning H 380® powder
consistently provided subsonic velocities of the projectiles thereof as evidenced
by all 10 of the rounds exhibiting subsonic velocities of their projectiles and successful
operation of the bolt of the weapon on every round, including the final round which
is intended to lock the bolt in its open position. In each set of 10 rounds of the
cartridges made up with the powders other than H 380®, there was one or more rounds
which exhibited a sonic velocity, failed to successfully operate the bolt of the weapon,
or the standard deviation between the velocities of the 10 rounds varied uncontrollably
between about 15,24 to about 60,96 m/s (about 50 to about 200 fps). The rounds made
up from the H 380® powder provided a standard deviation of less than 6,1 m/s (20 fps).
The large variation in the standard deviation exhibited by those powders that were
slower or faster burning than the H 380® powder is unacceptable for reliable-firing
subsonic ammunition. Like cartridges were fired with like results from a M-16 weapon
having a 50,8 cm (20 inch) barrel. In all tests in which the present projectiles,
employing H 380® powder, were propelled at a subsonic velocity, there was no audibly
detectable sound generated by the projectile due to its movement through air.
[0043] Further cartridges were made up using the H 380 powder and projectiles having less
weight and tested as above. Specifically, projectiles having weights of 6,48, 7,45
and 8,16 g (100, 115 and 126 grains) were made and tested. None of these cartridges
fired consistently subsonic with a standard deviation within an acceptable range.
[0044] Cartridges containing 8,68 g (134 grain) projectiles and made up using H 380® powder
were fired from the M-16 weapon having a suppressor attached to the muzzle of the
barrel thereof. The projectiles from these cartridges also consistently were subsonic
in velocity and exhibited an acceptable standard deviation. The cartridges further
successfully operated the bolt of the weapon. Moreover, the total sound emanating
from the firing of the weapon was almost nonexistent. No audibly detectable sound
was generated by the flight of these projectiles through the air.
[0045] In one embodiment of the present invention, the projectile may be made to be readily
frangible upon impact with a solid or semi-solid target. To this end, there may be
incorporated into the mixture of tungsten and lead powders, up to about 0.10%, by
weight of a micronized polyolefin wax such as ACumist 12 available from Allied Signal,
Inc., of Morristown, NJ. This powder has a size of -0,058 + 0,037 mm (a mesh of -250
+ 400) and is also identified as a fine particle size oxidized polyethylene homopolymer.
This powder has been found to inhibit bonding of the metal powder particles to one
another and therefore, in the noted small quantities, does not materially adversely
affect the formability or acceptable strength properties of a solid cylinder that
is die-formed in the manner set forth hereinabove. A micronized polyolefin wax and
metal powders mixture, when formed into a projectile core encased in a light metal
jacket provides a projectile which performs in all material respects like a projectile
formed from only the metal powders, except with respect to the frangibility of the
projectile when it strikes a target. The degree of frangibility of the projectile
is a function of the quantity of micronized polyolefin wax employed, but should not
exceed about 0.10%, by weight, in order to obtain a sufficiently strong, self-supporting
cylinder.
[0046] With reference to Figure 7, the present invention further contemplates a round of
pistol ammunition 80 including a case 82 having a projectile 84 inserted in the open
end thereof. The projectile 84 includes first and second core elements 86 and 88 which
have been independently die formed and thereafter die-pressed into a jacket 90 as
described hereinabove.
[0047] One embodiment of the method for producing a projectile in accordance with the present
invention is depicted in Figure 8 and includes the steps of selecting tungsten and
lead powders and blending these powders into a mixture. A portion of these blended
powders is die-formed into a first core element and a further portion is die-formed
into a second core element. These two core elements are thereafter inserted into a
jacket that is loaded in a die. The core elements in the jacket are pressed into the
jacket with a pressure sufficient to cause the core elements to conform to and at
least partly fill the interior volume of the jacket. Thereafter, the open end of the
jacket, containing the dual core elements, is at least partially closed. Finally,
the projectile is recovered for subsequent incorporation into a round of ammunition.
[0048] Whereas specific examples of the components of the ammunition of the present invention
have been given, it is to be understood that a person skilled in the art, given the
present disclosure, may elect to employ other equivalent components. Accordingly,
it is intended that the invention be limited only in accordance with the claims appended
hereto.
1. A round of subsonic ammunition (10) comprising a projectile (24, 84) including a metal
jacket (52, 90) having a closed end (54), an open end (56), an internal volume (26),
a longitudinal centerline (64) and exhibiting lubricity properties with respect to
the barrel of a gun,
a core (25, 51) contained within said jacket (52, 90),
said core (25, 51) including first and second elements (40, 46; 86, 88), each of said
elements (40, 46; 86, 88) having opposite ends and being formed from a mixture of
a heavy metal powder and a lighter metal powder that is cold-compacted into a geometrical
shape suitable for being received in said jacket (52, 90), each of said elements (40,
46; 86, 88) exhibiting greater density thereof adjacent its opposite ends than its
density adjacent a location equidistant between its opposite ends, said first and
second elements (40, 46; 86, 88) being inserted into said jacket (52, 90) in stacked
relationship to one another and subjected to a pressure to cause said elements (40,
46; 86, 88) to conform to and at least partially fill the jacket (52, 90).
2. The round of ammunition of claim 1 wherein said jacket (52, 90) is incompletely filled
by said elements (40, 46, 86, 88) and includes a portion of the length of said jacket
(52, 90) folded inwardly toward. said longitudinal centerline of said jacket (52,
90) to at least partially close said open end (56) of said jacket (52, 90).
3. The round of ammunition of claim 1 wherein the density of each of said first and second
elements (40, 46, 86, 88) adjacent the opposite ends thereof is greater than the density
of lead.
4. The round of ammunition of claim 1 wherein said first metal powder is tungsten metal
powder.
5. The round of ammunition of claim 1 wherein said lighter metal powder is lead.
6. The round of ammunition of claim 1 wherein said projectile (24) is suitable for firing
from a 5.56 mm weapon and possesses a weight of at least 8.68g (134 grains).
7. The round of ammunition of Claim 1 wherein said mixture of metal powders. includes
a further powder which inhibits bonding of the said metal powders to one another.
8. The round of ammunition of Claim 7 wherein said further powder comprises micronised
polyolefin wax.
9. The round of ammunition of Claim 8 wherein said further powder comprises a fine particle
size oxidised polyethylene homopolymer or the chemical and physical equivalent thereof.
10. A method of manufacturing a round of subsonic ammunition (10) comprising a projectile
(24, 84) including a metal jacket (52, 90) having a closed end (54), an open end (56),
an internal volume (26), a longitudinal centerline (64), a core (25, 51) contained
within said jacket (52, 90), and exhibiting lubricity properties with respect to the
barrel of a gun,
the method comprising the steps of:
forming said core (25, 51) from first and second elements (40, 46; 86, 88), each of
said elements (40, 46; 86, 88) having opposite ends and being formed from a mixture
of a heavy metal powder and a lighter metal powder that is cold-compacted into a geometrical
shape suitable for being received in said jacket (52, 90), each of said elements (40,
46; 86, 88) exhibiting greater density thereof adjacent its opposite ends than its
density adjacent a location equidistant between its opposite ends,
inserting said first and second elements (40, 46; 86, 88) into said jacket (52, 90)
in stacked relationship to one another and
subjecting said elements to a pressure to cause said elements (40, 46; 86, 88) to
conform to and at least partially fill the jacket (52, 90).
11. The method of claim 10 wherein said jacket (52, 90) is incompletely filled by said
elements (40, 46, 86, 88) and a portion of the length of said jacket (52, 90) is folded
inwardly toward said longitudinal centerline of said jacket (52, 90) to at least partially
close said open end (56) of said jacket (52, 90).
1. Unterschail-Munitionssatz (10), der ein Projektil (24, 28), das einen Metallmantel
(52, 90) mit einem geschlossenen Ende (54) enthält, ein offenes Ende (56), ein Innenvolumen
(26), eine Längsmittellinie (64) umfasst und Schmiereigenschaften bezüglich des Laufs
einer Waffe zeigt,
mit einem Kem (25, 51), der innerhalb des Mantels (52, 90) enthalten ist,
wobei der Kern (25, 51) erste und zweite Elemente (40, 46; 86, 88) aufweist, wobei
jedes der Elemente (40, 46; 86, 88) gegenüberliegende Enden aufweist und aus einer
Mischung aus einem schweren Metallpulver und einem leichteren Metallpulver hergestellt
ist, das zu einer geometrischen Form kaltverpresst ist, die geeignet ist, innerhalb
des Mantels (52, 90) aufgenommen zu werden, wobei jedes der Elemente (40, 46; 86,
88) benachbart seiner gegenüberliegenden Enden eine größere Dichte aufweist als dies
ihrer Dichte benachbart zu einer Stelle entspricht, die zwischen den gegenüberliegenden
Enden gleichmäßig beabstandet ist, wobei die ersten und zweiten Elemente (40, 46;
86, 88) in gestapelter Anordnung zueinander in den Mantel (52, 90) eingesetzt sind
und einem Druck unterworfen sind, um diese Elemente (40, 46; 86, 88) unter zumindest
teilweiser Ausfüllung des Mantels (52, 90) an diesen anzupassen.
2. Munitionssatz nach Anspruch 1, wobei der Mantel (50, 90) durch die Elemente (40, 46;
86, 88) unvollständig gefüllt ist und einen Teil der Länge des Mantels (52, 90) aufweist,
der nach innen in Richtung auf die Längsmittellinie des Mantels (52, 90) gefaltet
ist, um das offene Ende (56) des Mantels (52, 90) zumindest teilweise zu schließen.
3. Munitionssatz nach Anspruch 1, wobei die Dichte jedes der ersten und zweiten Elemente
(40, 46; 86, 88) benachbart ihrer gegenüberliegenden Enden größer als die Dichte von
Blei ist.
4. Munitionssatz nach Anspruch 1, wobei das erste Metallpulver Wolframmetallpulver ist.
5. Munitionssatz nach Anspruch 1, wobei das leichtere Metallpulver Blei ist.
6. Munitionssatz nach Anspruch 1, wobei das Projektil (24) geeignet ist zum Schießen
aus einer 5,56 mm Waffe und ein Gewicht von mindestens 8,68 g (134 grains) aufweist.
7. Munitionssatz nach Anspruch 1, wobei die Mischung aus Metallpulvem ein weiteres Pulver
enthält, das die Bindung der Metallpulver aneinander verhindert.
8. Munitionssatz nach Anspruch 7, wobei das weitere Pulver mikronisiertes Polyolefinwachs
umfasst.
9. Munitionssatz nach Anspruch 8, wobei das weitere Pulver ein oxidiertes Polyäthylenhomopolymer
oder eines seiner chemischen und physikalischen Äquivalente mit feiner Partikelgröße
umfasst.
10. Verfahren zum Herstellen eines Unterschall-Munitionssatzes (10) der ein Projektil
(24, 84), das einen Metallmantel (52, 90) mit einem geschlossenen Ende (54) aufweist,
ein offenes Ende (56), ein inneres Volumen (26), eine Längsmittellinie (64), einen
Kem (25, 51), der innerhalb des Mantels (52, 90) angeordnet ist, umfasst und Schmiereigenschaften
bezüglich des Laufs einer Waffe aufweist,
wobei das Verfahren die folgenden Verfahrensschritte enthält:
Herstellen des Kerns (25, 51) aus ersten und zweiten Elementen (40, 46; 86, 88), wobei
jedes dieser Elemente (40, 46; 86, 88) gegenüberliegende Enden aufweist und aus einer
Mischung aus einem schweren Metallpulver und einem leichteren Metallpulver hergestellt
ist, die in eine geometrische Form kaltverdichtet wurde, die geeignet ist, im Mantel
(52, 90) aufgenommen zu werden, wobei jedes der Elemente (40, 46; 86, 88) eine größere
Dichte an ihren gegenüberliegenden Seitenenden aufweist, als dies der Dichte benachbart
einer Stelle entspricht, die zu seinen gegenüberliegenden Enden gleichmäßig beabstandet
ist;
Einsetzen der ersten und zweiten Elemente (40, 46; 86, 88) in den Mantel (52, 90)
in einer gestapelten Beziehung zueinander, und
Unterwerfen der Elemente unter einen Druck, um zu bewirken, dass sich die Elemente
(40, 46; 86, 88) an den Mantel (52, 90) anpassen und ihn mindestens teilweise füllen.
11. Verfahren nach Anspruch 10, wobei der Mantel (52, 90) durch die Elemente (40, 46;
86, 88) unvollständig gefüllt ist und wobei ein Teil der Länge des Mantels (52, 90)
nach innen in Richtung auf die Längsmittellinie des Mantels (52, 90) gefaltet wurde,
um das offene Ende (56) des Mantels (52, 90) zumindest teilweise zu schließen.
1. Cartouche de munition subsonique (10) comprenant un projectile (24, 84) comprenant
une enveloppe en métal (52, 90) ayant une extrémité fermée (54), une extrémité ouverte
(56), un volume interne (26), un axe longitudinal (64) et présentant des propriétés
de lubrification par rapport au canon d'un fusil ;
un noyau (25, 51) contenu à l'intérieur de ladite enveloppe (52, 90) ;
ledit noyau (25, 51) comprenant des premiers et des deuxièmes éléments (40, 46
; 86, 88), chacun desdits éléments (40, 46 ; 86, 88) ayant des faces d'extrémité opposées
et étant formé à partir d'un mélange composé d'une poudre d'un métal lourd et d'une
poudre d'un métal plus léger qui est compressé à froid pour lui donner une forme géométrique
adaptée pour être reçue dans ladite enveloppe (52, 90), chacun desdits éléments (40,
46 ; 86, 88) présentant une densité adjacente à ses faces d'extrémité opposées plus
élevée de ce mélange que la densité adjacente à un emplacement équidistant entre ses
faces d'extrémité opposées, lesdits premiers et deuxièmes éléments (40, 46 ; 86, 88)
étant introduits dans ladite enveloppe (52, 90) selon une relation en empilement les
uns par rapport aux autres et étant soumis à une pression susceptible d'amener lesdits
éléments (40, 46 ; 86, 88) à épouser et à remplir au moins partiellement l'enveloppe
(52, 90).
2. Cartouche de munition selon la revendication 1 dans laquelle ladite enveloppe (52,
90) est complètement remplie avec lesdits éléments (40, 46 ; 86, 88) et comprend une
portion de la longueur de ladite enveloppe (52, 90) recourbée vers l'intérieur, vers
ledit axe longitudinal de ladite enveloppe (52, 90) pour fermer au moins partiellement
ladite extrémité ouverte (56) de ladite enveloppe (52, 90).
3. Cartouche de munition selon la revendication 1 dans laquelle la densité de chacun
desdits premiers et deuxièmes éléments (40, 46 ; 86, 88) adjacente aux faces d'extrémité
opposées de ceux-ci est plus élevée que la densité du plomb.
4. Cartouche de munition selon la revendication 1 dans laquelle ladite première poudre
de métal est de la poudre de tungstène.
5. Cartouche de munition selon la revendication 1 dans laquelle ladite poudre d'un métal
plus léger est du plomb.
6. Cartouche de munition selon la revendication 1 dans laquelle ledit projectile (24)
est adapté pour être tiré depuis une arme de 5,56 mm et possède un poids d'au moins
8,68 g (134 grains).
7. Cartouche de munition selon la revendication 1 dans laquelle ledit mélange de poudres
de métal comprend une autre poudre qui empêche l'agglomération desdites poudres de
métal l'une avec l'autre.
8. Cartouche de munition selon la revendication 7 dans laquelle ladite une autre poudre
comprend de la cire polyoléfine micronisée.
9. Cartouche de munition selon la revendication 8 dans laquelle ladite une autre poudre
comprend un homopolymère de polyéthylène oxydé à fines particules ou un équivalent
chimique et physique de celui-ci.
10. Procédé de fabrication d'une cartouche de munition subsonique (10) comprenant un projectile
(24, 84) comprenant une enveloppe en métal (52, 90) ayant une extrémité fermée (54),
une extrémité ouverte (56), un volume interne (26), un axe longitudinal (64), un noyau
(25, 51) contenu à l'intérieur de ladite enveloppe (52, 90),et présentant des propriétés
de lubrification par rapport au canon d'un fusil,
ce procédé comprenant les étapes consistant à :
réaliser ledit noyau (25, 51) à partir des premiers et des deuxièmes éléments (40,
46 ; 86, 88), chacun desdits éléments (40, 46 ; 86, 88) ayant des faces d'extrémité
opposées et étant formé à partir d'un mélange composé d'une poudre d'un métal lourd
et d'une poudre d'un métal plus léger qui est compressé à froid pour lui donner une
forme géométrique adaptée pour être reçue dans ladite enveloppe (52, 90), chacun desdits
éléments (40, 46 ; 86, 88) présentant une densité adjacente à ses faces d'extrémité
opposées plus élevée de ce mélange, que la densité adjacente à un emplacement équidistant
entre ses faces d'extrémité opposées ;
introduire lesdits premiers et deuxièmes éléments (40, 46 ; 86, 88) dans ladite enveloppe
(52, 90) selon une relation en empilement les uns par rapport aux autres ; et
soumettre lesdits éléments à une certaine pression afin d'amener lesdits éléments
(40, 46 ; 86, 88) à épouser et à remplir au moins partiellement l'enveloppe (52, 90).
11. Procédé selon la revendication 10 dans lequel ladite enveloppe (52, 90) est complètement
remplie avec lesdits éléments (40, 46 ; 86, 88) et une portion de la longueur de ladite
enveloppe (52, 90) est recourbée vers l'intérieur, vers ledit axe longitudinal de
ladite enveloppe (52, 90) pour fermer au moins partiellement ladite extrémité ouverte
(56) de ladite enveloppe (52, 90) .