U.S. patent application number 10/010009 was filed with the patent office on 2002-12-05 for dual core ammunition.
This patent application is currently assigned to Olin Corporation, a corporation of the State of Virginia. Invention is credited to Halverson, Henry J..
Application Number | 20020178963 10/010009 |
Document ID | / |
Family ID | 26680628 |
Filed Date | 2002-12-05 |
United States Patent
Application |
20020178963 |
Kind Code |
A1 |
Halverson, Henry J. |
December 5, 2002 |
Dual core ammunition
Abstract
A jacket precursor, a pellet first core precursor, and a second
core precursor are provided. The pellet and second core precursor
are inserted into the jacket precursor. The second core precursor
is pressed against the pellet so as to deform the pellet to fill a
frontal volume of the jacket precursor as a first core with
relatively less (if any) deformation of the second core precursor.
An aft portion of the jacket precursor is deformed to contain the
second core precursor as a second core. Preferred embodiments are
formed substantially as drop-in replacements for existing bullets.
A match embodiment features a lead rear core and a very light front
core (e.g., a carbonate powder). A non-toxic embodiment comprises a
tin front core and a harder rear core.
Inventors: |
Halverson, Henry J.;
(Collinsville, IL) |
Correspondence
Address: |
WIGGIN & DANA LLP
ATTENTION: PATENT DOCKETING
ONE CENTURY TOWER, P.O. BOX 1832
NEW HAVEN
CT
06508-1832
US
|
Assignee: |
Olin Corporation, a corporation of
the State of Virginia
|
Family ID: |
26680628 |
Appl. No.: |
10/010009 |
Filed: |
November 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60294169 |
May 29, 2001 |
|
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Current U.S.
Class: |
102/516 |
Current CPC
Class: |
F42B 30/02 20130101 |
Class at
Publication: |
102/516 |
International
Class: |
F42B 012/00; F42B
010/00; F42B 030/00 |
Claims
What is claimed is
1. A method for manufacturing a bullet comprising: providing a
jacket precursor; providing a pellet first core precursor;
inserting the pellet into the jacket precursor; providing a second
core precursor; inserting the second core precursor into the jacket
precursor aft of the pellet; pressing the second core precursor
against the pellet so as to deform the pellet to fill a frontal
volume of the jacket precursor as a first core, with relatively
less deformation of the second core precursor; and deforming an aft
portion of the jacket precursor to contain the second core
precursor as a second core.
2. The method of claim 1 wherein: a forward half of the jacket
precursor is already in a substantially final shape prior to
insertion of the pellet.
3. The method of claim 1 wherein: said pressing comprises at least
two stages, a first relatively low force/pressure stage deforming
the pellet to substantially fill said frontal volume and a second
relatively high force/pressure stage deforming the second core
precursor to laterally expand to fill an aft volume of the jacket
precursor.
4. The method of claim 1 wherein: the second core precursor is
provided having a convex front surface and a lateral surface which
is cylindrical along a majority of a length of the second core
precursor.
5. The method of claim 1 wherein: the second core precursor is
provided having essentially a convex front surface, a cylindrical
lateral surface, and a convex rear surface.
6. The method of claim 1 wherein: the pellet has a density less
than 30% of a density of the second core.
7. The method of claim 1 wherein the pellet is provided as a
sphere.
8. The method of claim 7 wherein the second core precursor is
provided as a circular cylinder.
9. The method of claim 1 wherein the first and second cores
abut.
10. The method of claim 1 wherein the first core is essentially
pure tin having a tin content of at least 99.85%, by weight, a
yield strength of 11.0 MPa or less and a hardness of from about 3
to about 5 HB.
11. The method of claim 10 wherein the second core is essentially
pure copper.
12. The method of claim 10 wherein the second core is essentially a
polymer filled with a tungsten-based material.
13. The method of claim 1 wherein the first core is substantially a
powder having a specific gravity less than 3.0.
14. The method of claim 13 wherein the second core is
lead-based.
15. The method of claim 1 further comprising loading the bullet in
a case selected from the group consisting of 0.357 Magnum 0.357
Sig, 0.38 Special, 0.40 Smith & Wesson, 9 mm Luger, and 10 mm
Automatic to form a cartridge.
16. The method of claim 15 wherein the case is 9 mm Luger.
17. The method of claim 15 wherein the loading inserts the bullet
into the case so that the cartridge has a length of 1.165-0.025
inch.
18. The bullet of claim 1 having a maximum diameter between 0.35
and 0.46 inch.
19. A bullet comprising: a jacket; a first core contained within
the jacket; and a second core contained within the jacket aft of
the first core; wherein the second core is lead-based and the first
core consists in major part of a non-metallic powder.
20. The bullet of claim 19 wherein: the first core comprises at
least 80.0 weight percent of one or more carbonates; the second
core comprises at least 95.0 weight percent lead; and the jacket
comprises at least 50.0 weight percent copper.
21. The bullet of claim 19 being an ogival bullet.
22. The bullet of claim 19 being full metal case, non-hollowpoint
bullet.
23. The bullet of claim 19 wherein the bullet is of nominal 9 mm
caliber and has a mass of 123.5-124.5 grains.
24. A bullet comprising: a jacket; a first core contained within
the jacket; and a second core contained within the jacket aft of
the first core, wherein: the first core consists of at least 50
weight percent tin; and the second core consists of at least 50
weight percent tungsten.
25. The bullet of claim 24 wherein: the first core has
deformability effective so that the bullet will not defeat level 2
body armor when impacted thereon.
26. The bullet of claim 24 wherein: the first core comprises at
least 80.0 weight percent tin; the second core comprises at least
95.0 weight percent tungsten-filled polymer; and the jacket
comprises at least 50.0 weight percent copper.
27. The bullet of claim 24 wherein: the bullet has a weight of
120-125 grains.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims benefit of U.S. patent application
Ser. No. 60/294,169 filed May 29, 2001 and entitled "Dual Core
Ammunition." The disclosure of Ser. No. 60/294,169 is incorporated
by reference herein as if set forth at length.
BACKGROUND OF THE INVENTION
[0002] (1) Field of the Invention
[0003] This invention relates to small arms ammunition, and more
particularly to bullets particularly useful in common calibers of
centerfire pistol and revolver (collectively "pistol")
ammunition.
[0004] (2) Description of the Related Art
[0005] A variety of cartridge sizes exist which may be used in
pistols, rifles or both. Among key common pistol ammunition rounds
are: 0.380 Automatic (also commonly designated 9 mm Kurz), 9 mm
Luger (also commonly designated 9.times.19 and 9 mm Parabellum),
0.40 Smith & Wesson (S&W), 45 Automatic (also commonly
designated Automatic Colt Pistol (ACP)) and 10 mm Automatic rounds.
General dimensions of and pistol rounds are disclosed in Voluntary
Industry Performance Standards for Pressure and Velocity of
Centerfire Pistol and Revolver Ammunition for the Use of Commercial
Manufacturers ANSI/SAAMI Z299.3-1993 (American National Standards
Institute, New York, N.Y.). A newer round, the 0.357 Sig is also
gaining acceptance.
[0006] After many decades of use of the 0.45 ACP round, in the
1980's the US Army adopted a 9 mm Luger full ogival, pointed, full
metal case (FMC, a.k.a, full metal jacket (FMJ)) round as the
standard round for use in military sidearms. The parameters for the
M882 9 mm Luger rounds purchased by the US military are shown in
United States Military standard MIL-C-70508, the disclosure of
which is incorporated by reference in its entirety herein as if set
forth at length.
[0007] Historically, pistol bullets have been of all lead or of
jacketed lead constructions. More recently, environmental toxicity
concerns have led to the development of lead-free alternatives.
[0008] Various powder metallurgy alternatives to lead bullets are
disclosed in U.S. Pat. No. 5,399,187 of Mravic et al.
[0009] U.S. Pat. Nos. 5,500,183 of Noordegraaf et al. and 6,016,754
of Enlow et al. disclose use of tin-based bullets and cores
thereof.
[0010] International Application PCT/US96/17664 (WO97/20185) of
Olin Corporation and Valdez et al. discloses a number of lead-free
dual core pistol bullets. Among examples are bullets having rear
cores of sintered copper-ferrotungsten and front cores of lead or
calcium carbonate powder.
BRIEF SUMMARY OF THE INVENTION
[0011] I have developed a novel manufacturing technique and applied
it to the manufacture of novel bullets. A jacket precursor, a first
core precursor, and a second core precursor are provided. The first
and second core precursor are inserted into the jacket precursor.
The second core precursor is pressed against the first so as to
deform the first to fill a frontal volume of the jacket precursor
as a first core with relatively less (if any) deformation of the
second core precursor. An aft portion of the jacket precursor is
deformed to contain the second core precursor as a second core.
[0012] Preferred embodiments are formed substantially as drop-in
replacements for existing bullets. To achieve the desired mass at a
given ogival contour, the portion of the bullet aft of the ogive
may be a bit longer than the replaced bullet and may be seated
deeper in the case. A match embodiment features a lead rear core
and a very light front core (e.g., a carbonate powder). A non-toxic
embodiment comprises a tin front core and a harder rear core. The
first core precursor may be formed as a pellet and, more
particularly, a spherical pellet. The second core precursor may be
formed having a cylindrical portion and one or two convex end
portions.
[0013] The details of one or more embodiments of the invention are
set forth in the accompanying drawings and the description below.
Other features, objects, and advantages of the invention will be
apparent from the description and drawings, and from the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a cut away view of a pistol cartridge.
[0015] FIG. 2 is a cross-sectional view of a bullet useful in the
cartridge of FIG. 1.
[0016] FIGS. 3-7 are longitudinal cross-sectional views of
intermediate manufacturing stages of the bullet of FIG. 2.
[0017] FIG. 8 is a longitudinal cross-sectional view of a second
bullet.
[0018] FIGS. 9-10 are longitudinal cross-sectional views of
intermediate manufacturing stages of the bullet of FIG. 8.
[0019] Like reference numbers and designations in the various
drawings indicate like elements.
DETAILED DESCRIPTION
[0020] FIG. 1 shows, a cartridge 20 including a case 22, a bullet
24, a propellant charge 26, and a primer 28. Preferably, the case
and primer are of conventional dimensions and materials such as
those of the M882 round. In the illustrated embodiment, the case is
unitarily formed of brass and is symmetric about a central
longitudinal axis 100 it shares with the bullet. The case includes
a wall 30 extending from a fore end 32 to an aft end 34. At the aft
end of the wall, the case includes a head 36. The head has front
and aft surfaces 38 and 40. The front surface 38 and the interior
surface 41 of the wall 30, define a cavity configured to receive
the propellant charge 26. The head has surfaces 44 and 46 defining
an approximately cylindrical primer pocket extending forward from
the aft surface 40. The head has a surface 48 defining a flash hole
extending from the primer pocket to the cavity. In the illustrated
embodiment, the surface 48 and flash hole 49 defined thereby are
cylindrical, e.g., of uniform circular cross-section.
[0021] The primer 28 includes a metal cup formed as the unitary
combination of a sleeve portion and a web portion spanning the
sleeve at an aft end of the sleeve. Preferably a nontoxic,
lead-free (e.g., dinol-based) primer charge is contained within the
cup along a forward surface of the web. Forward of the primer
charge, an anvil is disposed across the cup and has aft and forward
surfaces and at least one venting aperture (vent) extending between
such surfaces. A paper disk or foil is disposed on the aft surface
of the anvil.
[0022] I have conceived a first embodiment of a bullet offering
improved accuracy such as for use in target or match competition.
The illustrated bullet 24 (FIG. 2) consists essentially of a
metallic jacket 70, a frontal core 72, and a rear core 74. It is
well recognized within the industry that the pointed FMC design
such as employed for the M882 round is inherently inaccurate. One
of the major geometric parameters affecting accuracy is the
location of the bullet's center of gravity (CG) with respect to the
nose surface. Accuracy of spin stabilized bullets improves as this
distance increases. One method commonly employed to increase this
distance is to remove a cylindrical section of the core from the
nose (including the jacket material covering the section) and
relocating the mass to the rear of the bullet to maintain
comparable weight. This is typically referred to as a hollow point
design. Another method is to flatten the nose, essentially creating
a meplat. The bullet's drag increases and consequently changes the
location of the center of pressure (CP). The CP is now closer to
the frontal surface and further from the CG. The greater the spread
in location of the CG and CP, the quicker the bullet will stabilize
from any initial yaw and thus more accurately follow the trajectory
as determined by the weapon's point of aim.
[0023] The first present embodiment improves accuracy of the bullet
by moving the CG rearward by replacing a portion of the
high-density core material, such as lead, with a lower density
material. For example, the front (nose) core 72 may be 2.5 grains
of sodium carbonate while the rear core 74 maybe 107.5 grains of
lead and the jacket 14.0 grains of brass. The bullet is
consequently slightly longer if desired to maintain a similar mass
but the CG is now relocated rearward. For example, the 9 mm (124
grain) FMC bullet used in the M882 cartridge has its CG located
1.00 caliber from the nose surface whereas with the first
embodiment example it is 1.18 calibers (an 18% relative shift). In
a side-by-side test the M882 round had an average 10 shot
dispersion of 3.6 inches at 50 yards whereas the first embodiment
example had only 1.9 inches for a 46% improvement. This is
consistent with the estimated improvement in dispersion as
calculated by PRODAS--an exterior ballistic computer program
produced by Arrow Tech Associates.
[0024] In an exemplary method of manufacture, the jacket 70 is
initially formed as a relatively right bullet jacket cup (FIG. 3).
This initial jacket precursor is pressed into a die (not shown)
having the desired ogive and nose profile with a punch (not shown)
containing the desired inside profile. This forms the jacket into a
secondary precursor stage (FIG. 4). The outside and inside surface
contours along at least a forward portion thereof are
advantageously not altered as a result of subsequent bullet forming
operations. The cores (more particularly as core precursors) are
inserted into the jacket preform (FIG. 5). In general, the greater
the difference in densities of the two cores, the greater will be
the rearward relocation of the CG in the assembled bullet.
Preferred nose core material is powdered sodium carbonate
consolidated into a core precursor pellet of spherical shape. The
powder may include a small amount of wax or other binder to
maintain integrity of the pellet during initial handling. Other
materials are acceptable. They would preferably have a density less
than 3.0 grams per cubic centimeter. They would also preferably be
relatively inert and non-toxic. A spherical shape is preferred
since its surface 73 will contact the jacket interior surface 71 to
self align along the central axis (geometric centerline) when
inserted into the jacket preform and thus maintain the overall CG
position on such axis.
[0025] In its initial precursor state, the rear core 74
advantageously has at least a convex front surface 75 and may have
a similarly convex rear surface 76. A cylindrical lateral surface
77 may join the two. Front-to-back core symmetry eliminates the
need to orient a unique front end around the front core precursor.
The radius of curvature R.sub.c of the front surface is
advantageously between the radius R.sub.1 of the rear core
precursor (i.e., such as would form the rear core into an obround
with domed hemispheric ends) and approximately the diameter (i.e.,
2R.sub.1) of the rear core precursor. This profiling helps avoid
damage to or deformation of the soft lead core during handling
prior to compaction (e.g., prior to and during insertion) by
effectively breaking the edge which would be associated with a
flat-ended cylinder. Other breaking of the edge, such as by
chamfering, may provide some of this benefit.
[0026] The hardness/strength of the low density pellet should be
less than that of the rear core precursor in order for it to be
pulverized back to its original powdered form during consolidation
(FIG. 6) and thus deform to assume the profile of the rear core's
front end surface along a portion 80 and the ogival nose portion of
the jacket interior surface 71 along a portion 81. Tests have shown
that the sodium carbonate sphere will crush at about five pounds
force (lb..function.) whereas the rear lead core will not deform
until at least 50 lb..function. is applied whereupon the sphere has
already deformed to fill the space allocated for the low density
material. As the force applied to the rear surface of the rear core
is increased, the diameter of the rear core expands to laterally
fill the interior volume of the jacket (e.g., at a force in excess
of 200 lb..function.). The bullet is then coned (FIG. 7) and finish
assembled (FIG. 8) using standard forming tools and techniques.
[0027] In general, the volume of the low density front core should
be sufficient, given its density, to provide the desired rearward
shift in CG. This will typically be well under 50% of the internal
volume of the jacket. A range of 5-40% is likely, with 10-20% being
more narrow.
[0028] A similar manufacturing process may be used to manufacture a
lead free non-toxic bullet 124 (FIG. 8). Key examples duplicate the
weight and ogival profile of existing pointed FMC bullets so as to
provide a drop-in replacement which may have a slightly different
length aft of the ogive. In one embodiment, the front core 172
consists of a soft malleable material (e.g., having a hardness less
than Brinell 10). The rear core 174 is likely harder than the front
core and has a density of at least 75% that of lead. Preferred
materials are: tin for the front core; and tungsten-filled nylon
resin having a density of 10.2 g/cc for the rear. Exemplary
material is available from RTP Company,Winona, Minn. and is
believed to contain a small amount of copper in addition to
tungsten.
[0029] An exemplary lead-free M882 replacement could include front
and rear core masses of 12.0 and 98.0 grains, respectively. Other
materials for the front core could include rubber, silicone,
glazing putty, and consolidated inert powders such as used in the
match bullet. The rear core could comprise nickel, copper, and
consolidated iron/tungsten powder partially sintered. To the extent
that the nature of the rear core material is allowed to be a little
stronger than lead in resisting handling damage, the core may more
easily be formed as a cylinder without convex ends. Advantageously,
in addition to being non-toxic, this bullet duplicates the
penetration performance of the lead-core bullet being replaced. It
is particularly desirable that the bullet not penetrate body armor
(e.g., of aramid fiber) as worn by law enforcement personnel to a
greater extent than the lead core bullet. The National Institute of
Justice, U.S. Dept. of Justice has set minimum performance
standards for body armor as detailed in NIJ Standard 0101.04,
"Ballistic Resistance of Police Body Armor". The standard states
that a Level 2 grade of body armor will offer protection against
all handgun ammunition except 44 Magnum, which requires a Level 3A
to prevent injury to the wearer. A test conducted in accordance
with the NIJ standard has confirmed that a Level 2 body armor will
stop the M882. However, if the entire bullet core consists of a
material having a hardness greater than Brinell 10 no deformation
of the bullet's nose profile will occur and the bullet will pass
through the armor. It will also defeat Level 3A protection. Under
similar conditions, the tin-nosed M882 replacement bullet 124 met
the NIJ requirement.
[0030] In general, the volume of the front core should be
sufficient to permit sufficient nose distortion at impact to not
penetrate a desired level of body armor. This will typically be
well under 50% of the internal volume of the jacket. A range of
5-40% is likely, with 10-20% being more narrow.
[0031] The exemplary non-toxic bullet 124 is produced in a similar
manner to the match bullet 24 except that the rear core precursor
174 is more cylindrical and initially contacts the jacket inside
surface and not the front core precursor 174 (FIG. 9). As force is
exerted on the rear surface of the rear core precursor the front
surface deforms and follows the contour of the jacket interior
surface, and then the front core precursor consolidating the tin
into the nose and in front of the rear core precursor (FIG. 10). An
exemplary 100 lb..function. force is required to completely deform
the tin sphere and 500 lb..function. to expand the rear core
precursor to fill the inside profile of the bullet. If the initial
rear core precursor diameter is too small, the tin would be forced
rearward between the rear core precursor and the jacket thus
reducing its effectiveness. The remaining steps in forming the
bullet (e.g., coning and finishing) are similar to those used in
completing the match bullet.
[0032] One or more embodiments of the present invention have been
described. Nevertheless, it will be understood that various
modifications may be made without departing from the spirit and
scope of the invention. For example, although certain advantages
may be particularly relevant within certain existing calibers of
ammunition and associated specifications, the inventive bullets may
be applied to other calibers and specifications either present or
future. Additions of features such as sealing disks, coatings, and
the like may also be useful for particular applications.
Accordingly, other embodiments are within the scope of the
following claims.
* * * * *