Note: Descriptions are shown in the official language in which they were submitted.
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Lead-free Projectile
Description
The present invention relates to a lead-free small-bore jacketed projectile.
Such ammunition is known in various designs. It may be divided into those with
hard cores
made of steel, into those with hard cores made from dense sintered material
and those with a
medium additional to the hard core such as lead, aluminium and/or air.
Together with this
commercially available ammunition is a steel jacket, generally configured as a
full jacket, i.e.
a plated steel jacket or a jacket made from a copper/zinc alloy (tombac
jacket). In this
connection, the jacket receives one or more cores and further media and
encloses said cores
and media at least in a liquid-tight manner.
Small arms ammunition and the manufacturing process thereof is known from EP-
A2-0 106
411. The correspondingly optimised projectiles principally serve as live
ammunition for
infantry and already have good aerodynamic properties. This ammunition,
however, does not
have the required high final ballistic energy required by marksmen, which is
necessary for
penetrating armour plating. A further drawback is the large amount of hard
lead (98% Pb +
2% Sn) in the core, which has a toxic effect on the environment both in blank
ammunition and
live ammunition and therefore is undesirable nowadays or even prohibited in
some countries.
A jacketed projectile (WO 99/10703) of increased penetration performance and
target
accuracy has a hard core made of tungsten carbide and, as an additional
medium, a soft core
made of lead (Pb/Sn 60/40) which are held with an interference fit in a
gastight manner via a
brass disc in the jacket. Thus the escape of heavy metals and/or vapour when
firing is
prevented; a toxic effect is, however, still present in the target area.
Additionally, the
manufacture of such a projectile is costly and too expensive for mass use
(infantry
ammunition).
A further jacketed projectile for 9 mm bore pistols is marketed under the
reference SWISS P
SELF 9 mm Luger (RUAG Ammotec, Thun/Switzerland, formerly RUAG ammunition
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Thun/Switzerland. In this case, the projective consists of two sleeves pushed
inside one
another, the inner sleeve sealed at the tail and open upwards, enclosing a
large air space with
the outer sleeve. This projective is, however, only designed for soft targets
and, in this case,
is able to be driven through smoothly; it may be manufactured as lead-free.
A jacketed projectile with a bore of up to 15 mm is known from DE-A1-107 10
113 which
comprises an ogival or conical front region, a cylindrical central part and a
conically
extending tail region. The ductile metallic jacket encloses a pointed hard
core made of
hardened steel or made of a sintered metal and is more or less freely held by
a shoe-like or
sheath-like support made from a ductile metal or made of synthetic material.
The core is only
in linear contact with the jacket in the region of its angular shoulder. The
penetrative action
of this projectile on armour plated targets is good; the target accuracy
thereof is however,
markedly reduced. In particular with an oblique impact of the target, the
front part of the
projectile jacket splinters and deforms and thereby presses the hard core out
of its initial
symmetrical axial position which, as the effective cross-section has become
greater, at least
reduces the penetration performance or even leads to ricochets.
Additionally, the
manufacture of the projectile is costly and, due to the more or less free
positioning of the hard
core, may not be carried out with great accuracy.
It is therefore the object of the invention to provide a small-bore projectile
(small-bore = bore
less than 0.5") suitable for hard targets, which may be manufactured
economically, has a high
penetration performance and target accuracy and does not release heavy metals
on firing or in
the target area. The projectile to be provided is intended, in particular, to
contain no lead in
the core. The projectile jacket is also intended not to splinter on a hard
target.
The projectile may be easily manufactured and in a hard target (sheet metal)
etc. transmits
almost the entire kinetic energy to the hard core which penetrates the target.
In this
connection, the mass remains preserved at 100%, at the bullet hole a mushroom-
shaped collar
is formed by the tombac jacket which corresponds to the original weight of the
jacket.
Thus it is proved that no heavy metals and/or metal vapour are released.
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The same may be detected for another embodiment of the invention. This
embodiment
exhibits a high final ballistic performance, despite there not being a hard
core over the entire
surface in cross-section, in practical tests no fragmentation was detected at
the target.
Advantageous developments of the subject of the invention are disclosed as
follows.
A projectile with an ogive-like outer shape and an air space is particularly
advantageous with
regard to ballistics. It has been shown, that the necessary pressing-in of the
hard core may be
carried out accurately and with relatively low forces. Additionally, the pulse
transmission of
the core, after a short displacement path, allows a penetration of the jacket
with lower energy
losses.
The features of a conical tail region of the hard core and a conical tip
protruding into the
hollow space of the jacket core are very advantageous for the central pulse
transfer from the
jacket core to the hard core.
To a considerable extent, the flying behavior of the projectile is provided by
the position of
the centre of gravity. The centre of gravity may be optimized by the
constructive design and
dimensioning of the hard core and, in particular, of the hollow space (bore)
in the jacket core.
Alloy tool steels are well suited to the hard core and may be machined and
surface-treated by
conventional means.
Identical materials for the outer jacket and the jacket core have proved to be
very economical
and also expedient with regard to the density, the assembly and the thermal
expansion.
A constriction in the outer jacket improves the connection to the cartridge
sleeve and allows
the simple assembly thereof.
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The thickening of the jacket in its front region reduces ricochets during
acute angle firing at
hard targets and also serves to determine the centre of gravity.
The aforementioned embodiments of the projectile appear to be particularly
suitable for
projectile types having a bore of 5.56 mm.
The current demand for lead-free projectiles is ensured with the choice of
material revealed
herein. Standard filling material made of heavy metal in conventional
projectiles may also be
dispensed with, as the position of the centre of gravity may be optimally
adjusted by the
dimensioning of the individual components and hollow spaces.
The invention is disclosed hereinafter with reference to the embodiments and
drawings, in
which:
Figure 1 is a projectile according to the invention, fitted into a cartridge
sleeve known per se;
Figure 2 is a sectional view through a preferred embodiment of the projectile
in Figure 1;
Figure 3 is a sectional view of an alternative solution of a lead-free
projectile;
Figure 4a is a conventional projectile (according to the prior art) when
striking the target;
Figure 4b is a projectile according to Figure 2 when striking the target; and
Figure 4c is a projectile according to Figure 3 when striking the target.
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The tip of a projectile 100 is denoted in Figure 1 by 1. A flange 21 is
inserted into the reduced
diameter of a peripheral constriction 6, and which is a component of a
cartridge 20 known per
se. A standard explosive 24 is located in the cartridge 20, which acts as a
propellant for the
projectile 100. An impact fuse 23 (SINTOX, trademark of the firm RUAG Ammotec
GmbH,
Furth, DE) is inserted in a base 22 of the cartridge 20.
The preferred rotationally symmetrical projectile 100 is visible in Figure 2
in an enlarged
sectional view.
The actual tip 1 is imaginary; in reality it is a tip in the shape of a
spherical cup 2. A small air
space 3 is located inside the projectile 100, which is formed between a hard
core 4 and an
outer jacket 5, as a result of the different radii. A jacket core 8 is
attached to the hard core 4
with form fit, and which has a central hollow space 10 in the form of a blind
hole. The centre
of gravity 7 of the projectile is located in the upper part of said hollow
space. An outer
peripheral annular groove 6 is located thereover, which is illustrated here,
portrayed as a
diameter; see Figure 1.
At the tail, the end of the jacket 5 is conically tapered and terminates in a
stepped portion at
an angle a of 30 , which stepped portion merges with a terminal flange 9 and
holds the two
cores 4 and 8 together with an interference fit.
The diameter of the projectile 100 denoted by K, the bore, in the present case
is 5.56 mm and
is of the SS 109 type. The diameter 6 of the constriction is 5.45 mm. The hard
core 4 weighs 4
g and is made of hardened tool steel (material according to DIN 1.5511) and
has been
phosphatised after carburizing (penetration depth = 0.3 - 0.5 mm). The surface
hardness is
570 HV1.
In this embodiment, the hard core 4 has a lower conical tip of 90 which rests
positively in a
corresponding recess (countersink) in the upper part of the jacket core 8.
This configuration
may be varied at will; a similar form of central centering action is, however,
advantageous,
which facilitates the insertion or pressing-in of the core and ensures the
rotational symmetry
of the projectile.
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A hard core 4 made from tombac has also proved expedient; surprisingly, this
produces a
similar final ballistic performance.
The projectiles may be manufactured by standard production devices and
substantially by
deep drawing and pressing.
The hard core may also be made from other materials, for example from sintered
materials
such as tungsten carbide. Other projectile jackets are also conceivable, which
have a similar
ductility to tombac. The jacket core may also consist of other materials which
have a similar
or greater density. In all alloys, however, consideration has to be given to
the deposition of
heavy metal during firing and at the target.
In Figure 3 a variant of the aforementioned projectile is shown, in this
connection the same
functional parts are provided with the same reference numerals.
In contrast to the subject according to Figure 2, in this case, the hard core
is dispensed with. A
single jacket core 8' similarly fills up the space of the hard core 4, in
Figure 2. The associated
hollow space 10' is shortened relative to the hollow space 10 and has a
smaller diameter. As a
result, the mass of the entire projectile 100' is increased, so that
approximately the same final
ballistic performance and effect is achieved at the target.
On the front face, the hollow space 10' tapers and is at least almost closed
so that, together
with the front part of the outer jacket 5, a compact tip is produced when
striking the target.
In both variants, measuring results, theoretical observations and comparisons
with other
projectiles (prior art) show exceptionally good results:
The hollow space 10 and/or 10' allows a transverse contraction in the gun
barrel (rifle) which,
relative to solid projectiles, leads to a reduction in wear (abrasion), in
particular in the rifling
grooves. At the same time, the firing velocity vo of the projectile 100 and/or
100' at the
muzzle is greater than with projectiles without a hollow space 10 and/or 10'.
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The low drag coefficient cd of a 5.56 mm projectile (SS109 type) according to
the invention,
after a 570 m flight distance (NATO target), still lead to an impact velocity
of 470 m/s; the
steel plate used was Stanag 4172 of 3.5 mm thickness with 55-70 HRB hardness
(400N/mm2)
and was perforated smoothly.
The precise spin stabilisation acts positively on the stability and
reproducibility of the flight
path, even with side wind. As a result of the choice of materials and the high
firing velocity,
the kinetic energy is greater than with comparable projectiles, as tests also
showed. The
precision of a standard weapon may be increased with the subject of the
invention. Thus, for
example, all fired shots (repeated fire) at a target distance of 25 m were
located in a dispersion
circle with a diameter < 50 mm. At a firing distance of 300 m, a standard
deviation SD < 35
mm could be detected. In practice, this means that of 20 fired shots, of which
18 are located in
a circular surface with a diameter of 110 mm, only two projectiles struck
approximately 80
mm offset from the centre (target).
As tests in firing against soap have shown, the requirements of the ICRC
(International
Committee of the Red Cross) are also completely fulfilled, with regard to
wound ballistics, in
contrast with numerous other projectiles according to the prior art.
Figure 4a shows a conventional hard core projectile 200 (prior art) before and
during impact
on the target Z (steel). The steel jacket 50 explodes at the target Z, a hard
core 40 consisting
of tungsten or steel penetrates the target Z, whilst, due to the high kinetic
energy, the lead core
30 which follows behind is partially liquefied and even partially vaporised by
sublimation on
impact. This may be seen by a vapour cloud 30' which, after the condensation
thereof, also
leaves traces of lead at the target.
A combination of elastic and plastic impact with high deformability takes
place in the
projectile 200 (fragmentation of material on all sides). The material of the
projectile 200
which is splintered at the target Z and which may still be detected, no longer
corresponds to
its initial weight at the muzzle.
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In contrast, on one projectile 100, in Figure 4b, the identical mass may also
be detected at the
target Z. In this connection, the hard core 4 (steel or tombac) also
penetrates the target Z. The
outer jacket 5 mushrooms up at the target Z into a deformed jacket 5' and
transmits almost
100% of the kinetic energy to the hard core 4 via its similarly ductile jacket
core 8; there is no
fragmentation of material, either on the jacket 5 or on the jacket core 8. The
pulse direction
remains preserved.
Figure 4c shows a similar view: the projectile 100' which is modified relative
to Figure 4b is
squashed at the target Z and penetrates with a tip 1' which is now flattened.
The pulse
direction also remains preserved, the jacket core 8' is displaced on impact
into the air space 3,
compressed and squashed which is denoted here by 8".
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List of Reference Numerals
1 Tip (imaginary)
Flattened, squashed tip
2 Spherical cup
3 Air space (hollow space)
4 Hard core (hardened steel; tombac)
Outer jacket (tombac)
5' Deformed jacket 5
6 Constriction/diameter
7 Centre of gravity
8 Jacket core
8' Jacket core
8" Squashed jacket core 8'
9 Flange at 5
Hollow space in 8
10' Hollow space in 8'
Cartridge sleeve
21 Flange at 20
22 Base of 20
23 Impact fuse
24 Explosive/propellant
Lead core
30' Vapour cloud made up of Pb
Hard core (tungsten; steel)
40' Lead vapour (sublimated Pb)
Steel jacket
100, 100' Projectiles
200 Conventional hard core ammunition (projectile)
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K Bore
Z Target (steel plate)
a Angle (base angle)
