U.S. patent application number 14/401653 was filed with the patent office on 2015-05-28 for lead-free ammunition for small-bore weapons.
This patent application is currently assigned to Nammo Vanasverken AB. The applicant listed for this patent is Nammo Vanasverken AB. Invention is credited to Ake Andersson, Fredrik Erninge, Henrik Johansson, Thomas Mauritzson.
Application Number | 20150144019 14/401653 |
Document ID | / |
Family ID | 49584046 |
Filed Date | 2015-05-28 |
United States Patent
Application |
20150144019 |
Kind Code |
A1 |
Andersson; Ake ; et
al. |
May 28, 2015 |
LEAD-FREE AMMUNITION FOR SMALL-BORE WEAPONS
Abstract
The invention relates to a lead-free projectile (5) having
improved performance and intended for small-bore weapons,
configured so that the quantity of toxic metal particles and gases
which is formed by the friction between the projectile (5) and the
inner side of the weapon upon firing of the projectile (5) is
reduced, at the same time as the performance of the projectile (5)
is improved or maintained. The projectile (5) is characterized in
that the core (6) of the projectile (5) comprises a front core part
(7), constituting the penetrator part of the projectile (5), and a
rear core part (8), constituting the ballast part of the projectile
(5), wherein the front and the rear core part (7, 8) are detachably
joined together with each other by a radial guide (9) configured
for mutual freedom of rotation between the front and rear core part
(7, 8), and in that the rear core part (8) comprises, on the one
hand, a cylindrical part and, on the other hand, a conical part
having a cone angle .alpha. within the range 5.degree.-9.degree.,
wherein the contact surface between the cylindrical part and the
inner side of the weapon 1 upon firing of the projectile (5)
constitutes less than 30% of the total surface area of the
projectile (5). The invention also relates to an improved cartridge
(1) and an improved method.
Inventors: |
Andersson; Ake; (Molltorp,
SE) ; Erninge; Fredrik; (Hjo, SE) ; Johansson;
Henrik; (Skovde, SE) ; Mauritzson; Thomas;
(Skovde, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nammo Vanasverken AB |
Karlsborg |
|
SE |
|
|
Assignee: |
Nammo Vanasverken AB
Karlsborg
SE
|
Family ID: |
49584046 |
Appl. No.: |
14/401653 |
Filed: |
May 16, 2013 |
PCT Filed: |
May 16, 2013 |
PCT NO: |
PCT/SE2013/000077 |
371 Date: |
November 17, 2014 |
Current U.S.
Class: |
102/514 |
Current CPC
Class: |
F42B 5/025 20130101;
F42B 5/285 20130101; F42B 12/74 20130101 |
Class at
Publication: |
102/514 |
International
Class: |
F42B 5/285 20060101
F42B005/285 |
Foreign Application Data
Date |
Code |
Application Number |
May 18, 2012 |
SE |
1200305-9 |
Claims
1. A lead-free projectile, having the length L.sub.tot, for
small-bore weapons, comprising a hard-metal core, wholly or
partially enclosed by a metal jacket, wherein the projectile (5) is
configured for a lower friction between the projectile and the
weapon upon firing of the projectile, so that the quantity of metal
particles and environmentally hazardous gases from the projectile
is reduced, at the same time as the performance of the projectile
is maintained or improved, wherein the core of the projectile
comprises a front core part, constituting the penetrator part of
the projectile, and a rear core part, constituting the ballast part
of the projectile, wherein: the front and the rear core part are
detachably joined together with each other by a radial guide
configured for mutual freedom of rotation between the front and
rear core part, the rear core part comprises a cylindrical core
part having the length L.sub.C and a conical core part having the
length L.sub.k, wherein the angle .alpha. for the conical core part
lies within the range 5.degree.-9.degree., and wherein the contact
surface between the jacket of the cylindrical core part and the
inner side of the weapon 1 constitutes less than 30% of the total
surface area of the projectile, the distance (L.sub.TP) between the
tip of the projectile and the center of gravity TP of the
projectile lies within the range 0.55
L.sub.tot.ltoreq.L.sub.TP.ltoreq.0.60L.sub.tot, the length L.sub.C
of the cylindrical part of the rear core part lies within the range
0.25L.sub.tot.ltoreq.L.sub.C.ltoreq.0.31L.sub.tot.
2. The lead-free projectile as claimed in claim 1, wherein the rear
core part comprises at least 90% unhardened steel.
3. The lead-free projectile as claimed in claim 1, wherein the
jacket comprises at least 90% steel plated with a thin layer of
copper.
4. The lead-free projectile as claimed in claim 1, wherein the
jacket is divided into a front jacket part, an intermediate jacket
part and a rear jacket part, wherein the thickness of the
intermediate jacket part is at least twice as thick as the
thickness of the front jacket part and the rear jacket part (13),
and in that the three jacket parts constitute three separate
components joined together with one another on the core of the
projectile by shrinkage or threading.
5. The lead-free projectile as claimed in claim 1, wherein the
intermediate jacket part is surface-treated by sulfating in order
to minimize the wear in the weapon.
6. The lead-free projectile as claimed in claim 1, wherein at least
30% of the rear core part (8) is conical.
7. The lead-free projectile as claimed in claim 1, wherein the
jacket-comprises inner longitudinal rifles or grooves for
preventing rotation of the front and rear core parts of the
projectile inside the jacket.
8. The lead-free projectile as claimed in claim 1, the jacket
comprises outer longitudinal rifles or grooves for reducing the
friction between the projectile and the weapon.
9. The lead-free projectile as claimed in claim 1, the jacket
comprises outer transverse rifles or grooves for reducing the
friction between the projectile and the weapon.
10. A Lead-free cartridge for small-bore weapons, in which the
proportion of toxic substances in the combustion gases from the
priming and propellant compositions of the cartridge 1 upon firing
has been eliminated or heavily reduced, at the same time as the
performance of the cartridge 1 is maintained or improved, wherein
the cartridge comprises a lead-free propellant powder, a lead-free
primer comprising a zinc-free priming composition, a lead-free case
and a lead-free projectile, wherein the projectile is configured as
claimed in claim 1.
11. A method for reducing the wear between a projectile, comprising
a hard-metal core wholly or partially enclosed by a metal jacket,
and a weapon, wherein the quantity of environmentally hazardous
gases and metal particles which are generated upon firing of the
projectile from the weapon is reduced, at the same time as the
performance of the projectile is maintained or improved, wherein
the core of the projectile is configured with a front core part,
constituting the penetrator part of the projectile, and a rear core
part, constituting the ballast part of the projectile, wherein the
front and the rear core part are arranged detachably joined
together with each other by a radial guide for mutual freedom of
rotation between the front and rear core part the rear core part is
configured with a cylindrical part and a conical part, so that the
contact surface between the jacket of the cylindrical part and the
inner side of the weapon upon firing of the projectile constitutes
less than 30% of the total surface area of the projectile the
distance (L.sub.TP) between the tip of the projectile and the
center of gravity TP of the projectile is chosen within the range
0.55L.sub.tot.ltoreq.L.sub.TP.ltoreq.0.60L.sub.tot in that the
length L.sub.C of the cylindrical part of the rear core part 8 is
chosen within the range 0.25
L.sub.tot.ltoreq.L.sub.C.ltoreq.0.31L.sub.tot.
12. The method as claimed in claim 11, wherein the thickness of the
jacket is made thicker on that part of the projectile which is in
contact with the inner side of the barrel of the weapon.
13. The method as claimed in claim 11, wherein the intermediate
jacket part is surface-treated by sulfating in order to minimize
the wear in the weapon.
14. The method as claimed in claim 11, wherein at least 30% of the
rear core part is configured as a truncated cone.
15. The method as claimed in claim 11, wherein the jacket (10) is
configured with inner longitudinal rifles or grooves for preventing
rotation of the front and rear core parts of the projectile inside
the jacket.
16. The method as claimed in claim 11, wherein the jacket is
configured with outer longitudinal rifles or grooves for reducing
the wear between the projectile and the barrel of the weapon.
17. The method as claimed in claim 11, wherein the jacket is
configured with outer transverse rifles or grooves for reducing the
wear between the projectile and the barrel of the weapon.
18. A Lead-free cartridge for small-bore weapons, in which the
proportion of toxic substances in the combustion gases from the
priming and propellant compositions of the cartridge 1 upon firing
has been eliminated or heavily reduced, at the same time as the
performance of the cartridge 1 is maintained or improved, wherein
the cartridge comprises a lead-free propellant powder, a lead-free
primer comprising a zinc-free priming composition, a lead-free case
and a lead-free projectile, wherein the projectile is configured as
claimed in claim 2.
19. A Lead-free cartridge for small-bore weapons, in which the
proportion of toxic substances in the combustion gases from the
priming and propellant compositions of the cartridge 1 upon firing
has been eliminated or heavily reduced, at the same time as the
performance of the cartridge 1 is maintained or improved, wherein
the cartridge comprises a lead-free propellant powder, a lead-free
primer comprising a zinc-free priming composition, a lead-free case
and a lead-free projectile, wherein the projectile is configured as
claimed in claim 3.
20. A Lead-free cartridge for small-bore weapons, in which the
proportion of toxic substances in the combustion gases from the
priming and propellant compositions of the cartridge 1 upon firing
has been eliminated or heavily reduced, at the same time as the
performance of the cartridge 1 is maintained or improved, wherein
the cartridge comprises a lead-free propellant powder, a lead-free
primer comprising a zinc-free priming composition, a lead-free case
and a lead-free projectile, wherein the projectile is configured as
claimed in claim 4.
Description
[0001] The present invention relates to a lead-free ammunition with
improved performance, especially intended for small-bore weapons of
the firearm and machine gun type.
BACKGROUND
[0002] One problem with modern-day conventional ammunition, also
referred to as conventional cartridge ammunition, is the presence
of toxic heavy metals, especially lead, which is found in the
projectile, propellant powder and priming system of the cartridge.
The use of conventional ammunition in training and conflict areas
means considerable loads on the environment, with subsequent risks
for animals and humans. Large-scale use additionally means costly
clean-ups for the restoration of the environment. In the USA it is
calculated that the American army uses 300 to 400 million
lead-containing cartridges per annum, the majority of which are
used in practice firings on practice ranges close to military
bases.
[0003] The cost of cleaning up contaminated training areas is
calculated at nine billion dollars. The cost of cleaning up
contaminated training and conflict areas in other parts of the
world is thought to be even higher.
[0004] A further problem with said conventional ammunition is the
toxic gases and particles/dust which are formed in the combustion
of the priming composition and propellant powder of the ammunition.
Furthermore, environmentally hazardous metal particles, above all
lead particles from the lead core of the projectile, but also zinc
and copper particles from the tombac jacket of the projectile are
generated by the friction which arises between the projectile and
the rifled inner side of the weapon barrel upon firing of the
projectile.
[0005] Minor quantities of lead and copper dust are also formed
when the projectile hits a target.
[0006] Discharge of toxic particles and gases poses a risk not only
for the marksman but also for humans in the surroundings.
[0007] There is therefore a need for ammunition in which
environmentally hazardous heavy metals in the projectile, the
propellant powder and the priming system are replaced with other
materials, or in which the proportion of environmentally hazardous
metals has been reduced to a level which is as low as possible and
which is acceptable.
[0008] In the light of the above, a new generation of projectiles
has recently been developed, in which lead has been replaced with
other materials. In patent specification US 20060107863 is
described a projectile in which the core of the projectile is made
up of a compacted metal powder comprising a mixture, or mixtures,
of iron powder, copper powder and tin powder. In patent
specification US 2008 0000 379 is described a projectile whose core
is made up of a composite material comprising a mixture of
compacted metal and mineral powder.
[0009] One problem with these composite-based projectiles is,
however, their low penetrability. The, generally speaking, lower
strength of the composite material compared with solid metals means
that composite projectiles are more easily splintered when they hit
their target, compared with lead projectiles.
[0010] In order to improve the penetrability and, at the same time,
address the environmental problem, projectiles having solid steel
cores have been developed. In patent specification US6973879 is
described a lead-free projectile in which the core consists of a
hardened steel.
[0011] The projectile lacks a conventional jacket, and has
therefore been replaced with a surface coating constituted by a
soft metal, copper, nickel, zinc, aluminum or mixtures thereof,
plated directly onto the steel core.
[0012] One problem with said steel projectile is the
environmentally hazardous metal particles and metal dust which are
generated by the friction which arises between the projectile and
the inner side of the weapon when the projectile is fired from the
weapon. The friction adversely affects the performance of the
projectile, at the same time as discharge of harmful metal
particles, primarily copper, nickel and zinc, is at risk of
exceeding permitted limit values, for example 2 mg/m.sup.3 for
respirable copper dust.
[0013] A further problem is the toxic substances which are formed
in the combustion of the priming and propellant compositions of the
ammunition.
[0014] Another problem is difficulties in adapting the projectile
to the different demands which are made with respect to performance
and the environment for different weapon applications.
OBJECT OF THE INVENTION AND DISTINGUISHING FEATURES THEREOF
[0015] A principal object of the present invention is an improved
lead-free projectile for small-bore weapons, configured such that
the friction between the projectile and the barrel of the weapon
upon firing of the projectile is reduced such that the proportion
of environmentally hazardous gases and metal particles is reduced,
at the same time as the performance of the projectile is maintained
or improved.
[0016] A further object of the present invention is a lead-free
cartridge for small-bore weapons, configured such that, when a
projectile is fired from the weapon, the quantity of toxic
substances in the combustion gases from the priming and propellant
compositions of the cartridge is reduced, at the same time as the
performance of the weapon is maintained or improved.
[0017] Another object of the present invention is a method for,
when a projectile is fired from a small-bore weapon, reducing the
wear between the projectile and the barrel of the weapon so that
the quantity of environmentally hazardous gases and metal particles
is reduced, at the same time as the performance of the projectile
is maintained or improved.
[0018] Yet another object of the present invention is a projectile
configuration which can easily be adapted to different performance
and environmental demands in different weapon applications.
[0019] Said objects, and other aims which have not been enumerated
here, are satisfactorily met by that which is stated in the present
independent patent claims. Embodiments of the invention are defined
in the dependent patent claims.
[0020] Thus, according to the present invention, a lead-free
projectile, having the length L.sub.tot, for small-bore weapons has
been provided, comprising a hard-metal core, wholly or partially
enclosed by a metal jacket, wherein the projectile is configured
for a lower friction between the projectile and the weapon upon
firing of the projectile, so that the quantity of metal particles
and environmentally hazardous gases from the projectile is reduced,
at the same time as the performance of the projectile is maintained
or improved, wherein the core of the projectile comprises a front
core part, constituting the penetrator part of the projectile, and
a rear core part, constituting the ballast part of the
projectile.
[0021] The projectile is characterized [0022] in that the front and
the rear core part are detachably joined together with each other
by a radial guide configured for mutual freedom of rotation between
the front and rear core part, [0023] in that the rear core part
comprises a cylindrical core part having the length L.sub.C and a
conical core part having the length L.sub.k, wherein the angle
.alpha. for the conical core part lies within the range
5.degree.-9.degree., and wherein the contact surface between the
jacket of the cylindrical core part and the inner side of the
weapon 1 constitutes less than 30% of the total surface area of the
projectile, [0024] in that the distance (L.sub.TP) between the tip
of the projectile and the center of gravity TP of the projectile
lies within the range
0.55L.sub.tot.ltoreq.L.sub.TP.ltoreq.0.60L.sub.tot, [0025] in that
the length L.sub.C of the cylindrical part of the rear core part
lies within the range
0.25L.sub.tot.ltoreq.L.sub.C.ltoreq.0.31L.sub.tot.
[0026] According to further aspects of the lead-free projectile, it
is the case according to the invention:
that the rear core part comprises at least 90% unhardened steel,
that the jacket comprises at least 90% steel plated with a thin
layer of copper, that the jacket is divided into a front jacket
part, an intermediate jacket part and a rear jacket part, wherein
the thickness of the intermediate jacket part is at least twice as
thick as the thickness of the front jacket part and the rear jacket
part, and that the three jacket parts constitute three separate
components joined together with one another on the core of the
projectile by shrinkage or threading, that the intermediate jacket
part is surface-treated by sulfating in order to minimize the wear
in the weapon, that at least 30% of the rear core part is conical,
that the jacket comprises inner longitudinal rifling or grooves for
preventing rotation of the front and rear core parts of the
projectile inside the jacket, that the jacket comprises outer
longitudinal rifling or grooves for reducing the friction between
the projectile and the weapon, that the jacket comprises outer
transverse rifling or grooves for reducing the friction between the
projectile and the weapon.
[0027] According to the present invention, a lead-free cartridge
for small-bore weapons, in which the proportion of toxic substances
in the combustion gases from the priming and propellant
compositions of the cartridge upon firing has been eliminated or
heavily reduced, at the same time as the performance of the
cartridge is maintained or improved, has also been provided.
[0028] The cartridge is characterized in that the cartridge
comprises a lead-free propellant powder, a lead-free primer
comprising a zinc-free priming composition, a lead-free case and a
lead-free projectile.
[0029] According to the present invention, a method has been
provided for reducing the wear between a projectile, comprising a
hard-metal core wholly or partially enclosed by a metal jacket, and
a weapon, wherein the quantity of environmentally hazardous gases
and metal particles which are generated upon firing of the
projectile from the weapon is reduced, at the same time as the
performance of the projectile is maintained or improved, wherein
the core of the projectile is configured with a front core part,
constituting the penetrator part of the projectile, and a rear core
part, constituting the ballast part of the projectile.
[0030] The method is characterized: [0031] in that the front and
the rear core part are arranged detachably joined together with
each other by a radial guide for mutual freedom of rotation between
the front and rear core part, [0032] in that the rear core part is
configured with a cylindrical part and a conical part, so that the
contact surface between the jacket of the cylindrical part and the
inner side of the weapon upon firing of the projectile constitutes
less than 30% of the total surface area of the projectile, [0033]
in that the distance (L.sub.TP) between the tip of the projectile
and the center of gravity TP of the projectile is chosen within the
range 0.55L.sub.tot.ltoreq.L.sub.TP.ltoreq.0.601L.sub.tot, [0034]
in that the length L.sub.C of the cylindrical part of the rear core
part is chosen within the range 0.25
L.sub.tot.ltoreq.L.sub.C.ltoreq.0.31L.sub.tot.
[0035] According to further aspects of the method, it is the case
according to the invention:
that the thickness of the jacket is made thicker on that part of
the projectile which is in contact with the inner side of the
barrel of the weapon, that the intermediate jacket part (12) is
surface-treated by sulfating in order to minimize the wear in the
weapon, that at least 30% of the rear core part is configured as a
truncated cone, that the jacket is configured with inner
longitudinal rifling or grooves for preventing rotation of the
front and rear core parts of the projectile inside the jacket, that
the jacket is configured with outer longitudinal rifling or grooves
for reducing the wear between the projectile and the barrel of the
weapon, that the jacket is configured with outer transverse rifling
or grooves for reducing the wear between the projectile and the
barrel of the weapon.
Advantages and Effects of the Invention
[0036] The invention implies a number of advantages and effects, of
which the most important are:
[0037] The replacement of environmentally hazardous heavy metals,
such as lead, in all the various parts of the cartridge, with
non-hazardous metals such as steel means that the adverse effect of
the lead on the environment can be eliminated, which in turn
eliminates the need for clean-up measures for restoration of the
environment.
[0038] By configuring the projectile such that the friction between
the projectile and the inner side of the barrel is reduced, at the
same time as the air resistance of the projectile is reduced, the
quantity of environmentally hazardous metal particles and dust from
the projectile can be reduced, whilst, at the same time, the
ballistics and performance of the projectile are improved.
[0039] The fact that the priming and propellant compositions of the
cartridge are configured such that the proportion of toxic
substances in the combustion gases from the weapon is eliminated or
reduced means that the risks for the marksman and for humans in the
surroundings can be heavily reduced.
[0040] The modular structure of the projectile having a two-part
core with mutual freedom of rotation between the cores enables
simple and rapid adaptation, fitting/exchange, of the front core
with regard to different environmental and performance demands
which can conceivably be placed on the projectile for different
applications.
[0041] For example, a projectile configuration can be chosen in
which the front core part/the penetrator is made of hardened steel
or tungsten carbide and the rear core part/the ballast is made of
cheaper unhardened steel.
[0042] The modular structure of the projectile with three-part
jacket enables simple and rapid fitting by shrinkage or threading
of the different jacket parts, with regard to the demands which are
placed on the jacket.
[0043] For example, a jacket configuration can be chosen in which
the intermediate part of the jacket is constituted by a softer
metal, whilst the front and the rear jacket part are made of a
harder metal.
[0044] Said modifications of the cartridge and of the projectile
result in increased safety for the marksman and for persons in the
vicinity. For example, the safety distance to the weapon can be
reduced, as can the ventilation requirements in shooting galleries,
which implies environmental advantages and cost savings.
[0045] Further advantages and effects of the invention will emerge
from a study and consideration of the following, detailed
description of the invention, with simultaneous reference to the
drawing figures, in which:
[0046] FIG. 1 shows schematically a longitudinal section of a
cartridge comprising a projectile, a propellant powder, a primer
and a case,
[0047] FIG. 2a shows schematically a longitudinal section of a
projectile comprising a projectile core and a jacket.
[0048] FIG. 2b shows schematically a special embodiment of the
cylindrical part of the projectile core in FIG. 2a, configured with
longitudinal grooves.
DETAILED DESCRIPTION OF EMBODIMENTS
[0049] As stated earlier, an overall aim of the present invention
is to eliminate or heavily reduce the proportion of environmentally
hazardous heavy metals in the various parts of a cartridge and to
reduce the proportion of toxic substances, gaseous as well as
particulate, which are formed in the combustion of the priming and
propellant compositions of the cartridge, at the same time as the
performance of the cartridge is maintained or improved.
[0050] Historically, the emphasis on product development for
small-bore ammunition has primarily been focused on improving the
performance of the ammunition. Only more recently have we begun to
study the impact of the ammunition on the environment.
[0051] Totally lead-free, civil or military small-bore ammunition
represents a relatively small niche in the current market, yet the
market is growing rapidly. Historically, heavy metals such as
mercury and lead, above all lead, have been and are still today the
most common type of material found in cartridge constructions.
[0052] It is not fully clear how a lead-free cartridge acts in a
ballistic respect, in terms of the weapon, the trajectory or the
target.
[0053] At present, there is only one 5.56.times.45 mm lead-free
cartridge which is NATO-qualified, namely: NAMMO's 5.56.times.45 mm
Ball Non Toxic 4 High Performance (NATO design AC/225-128A).
[0054] In order to manage to reproducibly produce a new lead-free
cartridge with fully encased steel core, having new lead-free
components in the priming chain, in the priming cartridge, in the
propellant powder, and in the projectile, so that the discharges of
toxic heavy metals are eliminated or lowered, at the same time as
the performance of the cartridge is maintained or improved, it is
not sufficient to change only the material, but rather changes to
the design of the projectile are also required.
[0055] FIG. 1 shows a preferred embodiment of a cartridge 1
according to the invention. The cartridge 1 comprises a lead-free
powder charge 2, a lead-free primer 3, a lead-free case 4 and a
lead-free projectile 5. The powder charge 2 preferably comprises an
extruded single-base powder free from harmful heavy metals. The
powder is impregnated and is surface-treated in an environmentally
friendly process in water. The primer 3 comprises a priming
composition 6 free from harmful heavy metals and zinc peroxide so
as to reduce the proportion of toxic substances in the combustion
gases.
[0056] The choice of powder type and priming composition 6 has been
made with a view to, on the one hand, minimizing the proportion of
toxic substances in the combustion gases and, on the other hand,
matching the ballistic properties of the projectile. The cartridge
case 4 is of standard type, free from environmentally hazardous
heavy metals. Experimental tests show that said propellant powder
means a reduction of the ammonia proportion in the combustion gases
by more than 50%, of the hydrogen cyanide proportion by about 75%,
and of the copper proportion by about 40%, compared with a
conventional propellant powder. Experimental tests also show that
said priming composition means a reduction of the zinc proportion
in the combustion gases by about 50%, compared with a priming
composition containing zinc peroxide.
[0057] In FIG. 2 is shown a preferred embodiment of a projectile 5
according to the invention. The projectile 5 comprises a hard-metal
core 6, wholly or partially enclosed by a jacket 10 made of a
metallic material. The core 6 is divided into two core parts, a
front core part 7, constituting the penetrator of the projectile 6,
and a rear core part 8, constituting the ballast of the projectile
6. The two core parts 7, 8 are detachably joined together with each
other by a radial guide 9 configured for mutual freedom of rotation
between the core parts 7, 8. The guide 9 can be constituted, for
example, by a lockable and openable friction coupling. Other types
of couplings can also possibly be used.
[0058] The modular structure of the core 6 means that different
core parts can easily be combined in dependence on the target type.
For example, the front core part 7 can comprise tungsten carbide
for target types in which high demands are placed on the
penetrability of the projectile 5. The modular structure also means
that the center of gravity (TP) of the projectile 5 can easily be
adjusted by combining different core parts with different
configuration, length, width, etc., which means easier optimization
of the ballistics of the projectile during its trajectory. The
joining together of the core parts 7, 8 is effected via a coupling
which achieves radial guidance and mutual freedom of rotation.
[0059] The two core parts 7, 8 are configured to minimize the
contact surface between the projectile 5 and the inner side of the
weapon in order thus to reduce the quantity of metal particles
which is torn away from the projectile 5 in connection with the
projectile 5 being fired from a barrel.
[0060] At the same time, the rear core part 8 is configured to
reduce the air resistance of the projectile 5 and thus improve the
external ballistics of the projectile 5. The front core part 7 is
configured as an oblong cone 5, which accounts for approximately
half the total length L.sub.tot of the projectile 5. The rear core
part 8 comprises, on the one hand, a cylindrical part and, on the
other hand, a conical part having the cone angle .alpha.. The
length L.sub.k of the conical core part amounts to maximally
0.24.times.L.sub.TOT and the cone angle .alpha. shall lie within
the range 5-9.degree.. Tests have shown that the cone angle .alpha.
of the projectile is optimally, given lowest possible air
resistance, 6.degree.+/-0.1.degree..
[0061] The cylindrical portion of the rear core part 8 is weakly
conical, with a cone angle .alpha. within the range
0.degree.<.alpha.<1.degree., preferably 0.55.degree.. The
reason is that the conical shape reduces the obtuse angle between
the core and the jacket 10, thereby reducing the friction forces
between the projectile 5 and the barrel of the weapon.
[0062] A short cylindrical portion achieves, however, a strong
reduction of the inner friction surface between the rear core part
8 and the jacket 10, which poses a problem, since the core 6 can
then acquire a different rotational velocity from the jacket 10,
causing the projectile 5 to become unstable. In order to prevent
different rotational velocities and thus the risk of instability,
the core 6, in a special embodiment in FIG. 2b, has been provided
with longitudinal grooves or rifling. The grooves 14 produce an
increased friction between the core 6 and the jacket 10 and thus
act as a friction joint. The joint is rotationally locked and
ensures that the core 6 rotates at the same speed as the jacket 10.
The groove length on the core 6 should be at least
0.15.times.L.sub.C. When the jacket 10 is missing, for example when
the jacket 10 has come off following impact against a hard target,
or when the jacket 10 is not yet fitted, no rotational locking is
in force, however, between the tip of the projectile, i.e. the
front core part 8, and the rear core part 8. Between the tip and
the core 6, radial guidance and freedom of rotation is in
force.
[0063] The grooves 14 also imply an advantage from the production
viewpoint, since the grooves 14 act as a tool in the fitting of the
core 6 and jacket 10.
[0064] The external ballistics/flying ability of the projectile 5
is determined in large part by the center of gravity T of the
projectile 5. For a 5.56 caliber projectile 5, the distance
(L.sub.TP) between the tip of the projectile 5 and the center of
gravity TP of the projectile shall ideally lie within the
range:
0.55L.sub.tot.ltoreq.L.sub.TP.ltoreq.0.60L.sub.tot.
[0065] Furthermore, the length L.sub.C of the cylindrical part of
the rear core part 8 shall be as short as possible and lie within
the range
0.25L.sub.tot.ltoreq.L.sub.C.ltoreq.0.31L.sub.tot.
[0066] The front core part 7, i.e. the penetrator, is preferably
produced from a hardened steel having a hardness of at least 500
Hv3. Other materials too, such as tungsten carbide, can
advantageously be used. The rear core part 8 is preferably produced
from a steel having a maximum hardness of 160 Hv3. The jacket 10 of
the projectile is preferably produced from a standard copper-based
material, also referred to as tombac. Preferably, the tombac jacket
10 comprises a mixture of 90% copper and 10% zinc. In an
alternative embodiment, the jacket comprises at least 90% steel
plated with a thin layer of copper. The jacket 10 is produced,
preferably, by a standardized method, for example by cold pressing
and upsetting.
[0067] In order to minimize the discharge of metals to the
environment, the thickness of the jacket 10 is greatest on the
cylindrical part of the jacket 10, that is to say on that part of
the jacket 10 which is in contact with the inner side of the barrel
upon firing of the projectile 5.
[0068] The thickness of the jacket 10 is expediently optimized by
being made thicker on the cylindrical part of the jacket where the
wear against the barrel occurs, preferably twice as thick as the
other parts of the jacket 10.
[0069] In a special embodiment, the jacket 10 is divided into a
front jacket part 11, an intermediate jacket part 12 and a rear
jacket part 13, wherein the intermediate jacket part 12 is at least
twice as thick as the front and the rear jacket part 12, 13. The
three jacket parts are here constituted by three separate
components, which can be joined together on the core of the
projectile 5, for example by shrinkage, welding or threading. The
advantage with a modularly constructed jacket 10, as with a
modularly constructed core 6, is that the jacket 10 can easily be
configured with regard to different ballistic and environmental
demands which can be placed on the projectile 5. For example, the
intermediate jacket part 12 can be made of a tombac material,
whilst the front jacket part 11 and the rear jacket part 13 are
made of a non-metallic material, for example a composite material.
Furthermore, the different jacket parts 11, 12, 13 can be
surface-treated in different ways. For example, the intermediate
jacket part 12 can be surface-treated, in order to minimize the
wear in the barrel, by sulfating or tinning, for example, whilst
the front jacket part 11 and the rear jacket part 13 are
surface-treated for the sole purpose of minimizing the air
resistance of the projectile 5 during its trajectory.
[0070] In a further special embodiment of the jacket 10, the jacket
10 comprises inner longitudinal rifling or grooves (not shown) for
preventing rotation of the core 6 of the projectile 5 inside the
jacket 10, compare with the earlier described special embodiment of
the cylindrical part of the core with grooves 14 or rifling
producing the same effect.
[0071] In a further special embodiment of the jacket 10, the jacket
10 comprises outer longitudinal grooves or rifling (not shown) for
reducing the wear between the projectile 5 and the barrel of the
weapon.
[0072] In another special embodiment of the jacket 10, the jacket
10 comprises outer transverse grooves or rifling (not shown) for
reducing the wear between the projectile 5 and the barrel of the
weapon.
[0073] The configuration of the projectile with extended and
optimized rear core part and smaller contact surface, in
combination with the higher strength of the projectile, has been
shown in tests to reduce the proportion of metal particles from the
projectile by 10-20%, at the same time as the ballistic properties
of the projectile have been improved. For example, the decrease in
velocity of the projectile during its trajectory has been reduced,
at the same time as the penetration in plate shooting is very good
up to at least 725 m.
[0074] The described configuration means that the projectile, in
tests according to NATO standard, can penetrate a steel plate of
3.5 mm thickness (SAE 1010/1020 having a hardness of 99-124 HB) at
a distance of at least 725 m, which is 27% better than is required
according to NATO standard at a firing distance of 570 m.
[0075] The improved ammunition inclusive of projectile has been
shown in tests to meet internal, external and terminal ballistic
requirements and other requirements according to NATO's STANAG 4172
and NATO Multi Manual Of Proof & Inspection
PFP(NAAG-LG/1-SG/1)D(2004)1 for 5.56-caliber military
ammunition.
[0076] This means that the ammunition meets the demands placed by
NATO on precision, pressure level, temperature, ballistic
trajectory consistency and safety when used in functional
weapons.
[0077] The invention is not limited to the embodiments shown, but
can be varied in different ways within the scope of the patent
claims. It will be appreciated, inter alia, that the number, size,
material choice and form of the materials included in the
ammunition and the component which are of importance to the
invention, for example propellant powder, priming composition, can
be adapted with regard to one another and with regard to other
included elements and components in the ammunition.
* * * * *