Note: Descriptions are shown in the official language in which they were submitted.
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127PlCA
The present invention relates to bullets for use in small arms ammunition and, in particular, to so-
called pre-fragmented bullets compri.~ing ajacket co~ g individual metal pieces, and to methods
5 of m~nllf~cturing bullets.
It has previous been proposed to provide a pre-fragmented bullet comprising a copper jacket filled
with bird shot, which is intended to rupture on impact so as to create a wound resembling a scaled-
down shotgun wound.
One advantage of this prior bullet is that it produces massive tissue damage as deeply as the slug
penetrates. This prior bullet also has the advantage that it does not over-penetrate its primary target.
In other words, the bullet does not penetrate a target sufficiently with enough energy to exit from the
target, with the risk of hitting an llnint~ntlecl secondary target. Further, the prior bullet is so fragile
15 it bursts upon angular impact against a hard surface and, therefore, does not ricochet. In addition,
this prior bullet is less likely than any other bullet to penetrate walls, for example, in a domestic
scenario so as to endanger people in adjacent rooms or at the exterior of a building within which the
bullet is fired.
20 However, it is also a disadvantage of this prior bullet that it produces only shallow tissue penetration
and, therefore, may not sufficiently penetrate in side-to-side shots, shots involving intermediate
targets such as upper arms and other shots calling for deep penetration. Also, the prior bullet is
readily fr~gment~l by impact against, for example, car glass, car metal or building materials, which
a felon is likely to use for cover. Unlike a solid bullet, this prior bullet cannot be caused to bounce
25 or ricochet under, for example, an automobile body so as to hit a felon behind the automobile body.
It is accordingly on object ofthe present invention to provide a novel and improved bullet which acts
as a pre-fragmented projectile but which also is capable of penetrating hard obstacles.
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According to the present invention, there is provided a small arms ammunition bullet having a jacket
with a hollow interior having an open end and a closed end. A first core portion of thermoplastic
material is provided within the hollow interior at the closed end. A second core portion projects
through the open end and is formed by individual metal fragments compacted into an at least
5 substantially solid mass.
On impact against, for example, water, ballistic gelatin or living tissue, this bullet releases its energy
quickly, so that the jacket is upset and the individual fragments separate from one another and spread
apart from the main path of the bullet. However, this bullet is also capable of penetrating hard
10 obstacles when required.
By compaction of the individual fragments into a solid mass, the presence of voids within the jacket
is avoided and the bullet is therefore more stable when fired and, thus, more accurate.
15 The thermoplastic material fills the space within the jacket between the compacted fragment mass
and the closed end of the jacket, and light.-n~ the bullet, thus further improving the ballistics of the
bullet.
The bullet is manufactured by inserting the thermoplastic material into the hollow interior at the
closed end thereof, and then inserting individual pieces of metal onto the plastic material in the
20 hollow interior. By use of, for example, a swaging die, the thermoplastic material and the metal
pieces are compacted in the hollow interior so that the thermoplastic material fills the closed end of
the hollow interior and the metal pieces are compacted together into a substantially solid mass. A
further metal piece is then positioned on the solid mass at the open end of the hollow interior of the
jacket and is compacted against the mass as a part thereof projecting through the open end, the jacket
25 being collapsed at the open end onto the further metal piece to form a nose therewith.
The present invention will be more readily apparent from the following description of a preferred
embodiment thereof when taken in conjunction with the accompanying drawings, in which:-
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Figure 1 shows a plan view of components of a bullet during a first stage of the m~nllf~ctllre thereof;
Figure 2 shows a view taken in cross-section along the line 2-2 of Figure l;
Figure 3 shows a view taken in cross-section through a swaging die during compaction of some of
the components shown in Figures 1 and 2;
Figure 4 shows a view in vertical cross-section through the bullet components of Figures 1 and 2
during a subsequent step in the m~nllf~ture of the bullet;
Figure 5 shows a view taken in vertical cross-section through the finished bullet;
Figure 6 shows a view in vertical cross-section through a round of ammunition including the bullet
of Figure 5; and
Figure 7 shows a diagram illu~llaling the penetration of the bullet of Figure 5 into ballistic gelatin.
Referring firstly to Figure 1 and 2 of the accompanying drawings, reference numeral 10 indicates
generally a metal jacket which comprises a circular base 12 and a cylindrical wall 14 upst~n~1ing
from the base 12. The jacket 10 has a hollow interior 16, which has one end closed by the jacket
base 12, and an open end 18 opposite from the closed end.
The jacket 10, in the present embodiment of the invention, is made of copper. However it is
alternatively possible to substitute a copper alloy, alllminllm, an aluminum alloy or gilding metal
instead of copper.
In the m~mlf~tllre of a bullet employing the jacket 10, a ball or sphere 22 of polyethylene is inserted
into the closed end of the jacket. However, other thermoplastic materials may, if desired, be
~ul~ ul~d for polyethylene. Six #6 lead bird shot 24 are then placed on top of the thermoplastic ball
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20 within the jacket hollow interior 16 in a side-by-side arrangement. As can be seen from Figure
1, the shot 24 are arranged with a single shot 24 at the centre of the array, and with the rem~ining
five shot 24 evenly spaced around this central shot 24.
5 Next, five #9 shot 26 are arranged in an equally-spaced array, with each of the shot 26 resting on
three of the underlying shot 24.
The thermoplastic ball 20 and the shot 24 and 26 are then compacted in a swaging die indicated
generally by reference numeral 28 in Figure 3. The swaging die 28 is provided with a cylindrical
support 30, which abuts the base 12 of the jacket 10 and which has a diameter substantially equal
to that of the jacket 10. A punch 32, having a diameter substantially equal to the interior diameter
of the jacket 10, is then displaced downwardly against the shot 24 and 26. In this way the
thermoplastic ball 20 is deformed into a mass 33 which fills the closed lower end 60 of the jacket
10. Simultaneously the shot 24 and 26 are compacted together to form a substantially solid mass
15 indicated by reference numeral 34 in Figure 3.
In this connection, it is pointed out that the shot 24 and 26 should be arranged in the above-described
equally-spaced manner, rather than being simply dropped in a random manner into the jacket 10, in
order to avoid the formation of voids in the compacted mass 34 during the swaging operation and,
20 thereby, to avoid impairing the accuracy of the finished bullet in use.
Also, by arranging the shot 24 and 26 in the above-described equally spaced manner, dispersion of
the corresponding fragments of the bullet around the main bullet track, on impact of the bullet, is
ensured, thus increasing the chances of striking a vital organ or blood vessel that would not have
25 been struck by a similar impact of a non-pre-fragmented bullet.
By the use of swaging to compact the shot 24 and 26, as described, so as to avoid the formation of
voids in the compacted metal mass, the stability of the finished bullet when fired, and thus its
accuracy, are enhanced. Also, the swaging of the lead shot deforms the shot into a flattened
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somewhat disk-like shape which increases the damage caused by penetration of the finished bullet
into tissue as compared to conventional round shot. Further, the risk of over-penetration of a target
is likewise reduced.
5 Following the above-described swaging operation, a #4 Bk. shot 36 is placed centrally on top of the
swaged mass 34 as shown in Fig. 4. The shot 36 and the upper, open end of the jacket 10 are then
swaged in a nose-forming die (not shown) to form a nose indicated generally by reference numeral
38 in Figure 5, the nose 38 having a generally ogive shape with a flat circular tip end 39.
The nose 38 of the finished bullet 5, as shown in Figure 5, thus forms a tapered tip, with the shot 36
of Figure 4 deformed to con~tiblte, together with the solid mass 34, a larger solid mass 40 projecting
through the upper, open end of the jacket 10, and an upper portion 41 of the jacket wall 14 being
collapsed inwardly to penetrate the solid mass 40, as shown.
15 It has been found by experiment that the jacket 10 should advantageously have a wall thickness of
0.017 inch when the jacket 10 is made of copper or gilding metal and 0.021 inch when the jacket 10
is made of aluminum. More palticularly, a thickness greater than this will cause some deterioration
of the performance of the bullet when it impacts gelatin, i.e. the bullet will not expand optimally and,
therefore, may over-penetrate, whereas if the jacket wall thickness is less than this dimension the
20 bullet may not provide ol~lh~ ll penetration of obstacles.
This wall thickness may extend from the base to the top of the jacket 10. However, the jacket may
alternatively be tapered in its wall thickness, provided that the thickness of the jacket has the above
dimension from the open end of the jacket over one third of the total length of the jacket.
The total length L of the bullet in the present embodiment is 0.528 inch, the nose 42 projects by a
distance L1=0.074 inch beyond the jacket 10 and the tapered wall 41 extends over a distance of
L2=0.119 inch, cylindrical portion of the wall 14 extending over a distance L3=0.335 inch.
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Also, the circular tip end 39 of the nose 42 has a diameter D=0.080 inch, the finished bullet having
a diameter 0.355 inch.
Figure 6 shows the bullet in a complete ammunition round indicated generally by reference numeral
44, which includes a brass cartridge 45, a detonator 46 and a propellant 47.
Figure 7 diagrammatically illustrates penetration of the bullet when fired into a block of 10% 250A
ballistic gelatin 50 having a length of ten inches. The bullet has fragmented into a first fragment 52
formed by the nose 42 of the bullet, the jacket 10 being expanded and located behind the fragment
52, and further fr~gment~ 54 and 56, formed from the shot 24 and 26, respectively, being scattered
along tracks extending at about 45 from the main bullet path, indicated by reference numeral 58.
Occasionally, metal fragments 60 are spun off from the jacket 10.
It is to be understood that the size of the lead shot may vary, depending upon the calibre of the bullet.
Generally #5, #6, #9 and BB lead shot are well suited for the manufacture of bullets, while #4 Bk.
shot is well suited to form the nose of the bullet.
The thermoplastic m~tçri~l employed for the ball 20 serves to lighten the bullet. By lightening the
bullet, the velocity of the bullet when fired is increased and, in this way, the velocity can be
m~int~ined sufficiently high to ensure that the bullet fragments, and spreads apart the metal jacket,
upon impact. When this happens, the swaged shot come apart at about 45 to the main bullet path
58 as shown in Figure 7, around the main bullet path 58.
As will be apl)al~lll to those skilled in the art, the shot size and the diameter of the plastic ball 20
will vary, depending upon the calibre of the bullet, and also the number of shot employed may vary.
Thus, for example, in the case of a .44 calibre bullet, BB shot and a #4 Bk. shot may be employed,
whereas a .45 calibre bullet, #5 shot, #12 shot and #4 Bk. shot may be employed.
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The #4 Bk. shot (hard or regular) is heavy enough to provide sufficient weight at the front of the
bullet and, after being formed with a 3/4 inch ogive shape in a swaging die, as described, the bullet
will have a suitable profile for reliable feeding in both fully automatic and semi-automatic weapons.
S Also, instead of employing lead shot, it is alternatively possible to substitute bismuth shot.
As will be a~al~lll to those skilled in the art, various other modifications may be made in the above
described embodiments of the invention within the scope of the appended claims.
