Note: Descriptions are shown in the official language in which they were submitted.
CA 02613696 2007-12-10
-2-
Specification
1. Field of the Invention
This invention relates to a highly frangible non-toxic accurate projectile
used in small arms
applications and to the method for making it.
2. Description of the Previously Published Art
It is desirable to manufacture a highly frangible projectile fired at over
3000 feet per second that do
not damage a steel plate manufactured from AR500 steel having a thickness of
3/8 of an inch and V2
of an inch. It is also desirable that the frangible projectile have at least
an accuracy of two minutes
of angle at 100 meters.
The projectile must have enough strength in its composition that it does not
break apart while
passing through the barrel of a firearm having a rate of twist 7 to 1.
Currently, frangible projectiles fired at high velocities such as 3000 feet
per second do damage steel
plates made with AR500 steel and have accuracies substantially more than two
minute of angle at
100 meters.
OBJECTS OF THE INVENTION
It is an object of this invention to provide a highly frangible, accurate non-
toxic projectile which
does not damage steel plates constructed out of AR500 steel when shot at
velocities over 3000 feet
per second, constructed with a frangible jacket and frangible core that are
separately made from
metal particles mixed in liquid natural rubber, swaged and cured to a desired
hardness and strength.
It is further objvct of this invention to provide a process for making a non-
toxic, highly frangible
accurate projectile using standard conventional bullet assembly machinery.
These and furC~pr q~ppts of this invention will become more apparent as the
description of the
invention propq eds,
CA 02613696 2007-12-10
-3-
SUMMARY OF THE INVENTION
The foregoing and further objects and advantages are obtained by manufacturing
a frangible,
accurate projectile using a frangible jacket and frangible core separately
made from metal particles
mixed with liquid natural rubber, swaged and cured to a desired hardness.
The frangible bullet jacket and core are assembled into a highly frangible,
accurate projectile using
conventional bullet assembly equipment.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompany drawings,
FIG. 1 is a cross-sectional view of a frangible jacket
FIG. 2 is a cross-sectional view of a frangible core
FIG. 3 is a cross-sectional view of a seated frangible core inside a frangible
jacket
FIG. 4 is a cross-sectional view of a frangible projectile described in the
invention
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The current invention achieves the desired results by first constructing a
frangible bullet jacket out
of metal particles that are mixed in curable liquid natural rubber. The metal
particles may be of one
type metal or a combination of metals. Metals particles such as copper,
bronze, brass, tin, zinc, iron,
tungsten and bismuth are examples of suitable metal particles that can be
utilized in the formation
of the frangible bullet jacket. The metal particles may be powder, flakes or
chips and a combination
thereof. The liquid natural rubber should have a viscosity similar to skimmed
milk to be most
effective. There are suitable thinners that can be used to make the natural
liquid rubber less viscose
if desired.
Metal particles are mixed with a pre-determined amount of natural liquid
rubber and 60 to 1 is a
typical weight ratio of metal particles to liquid rubber. A suitable liquid
rubber thinner may be
added to the homogenous mixture if desired.
CA 02613696 2007-12-10
-4-
After the homogenous mixture of metal particles and liquid natural rubber are
mixed and all the
volatiles of the liquid natural rubber have completely evaporated, a suitable
dry lube is added to the
dried homogenous mixture and .5% is a typical amount that is used.
The homogenous mixture of metal particles, dried liquid rubber and dry lube
may be roller
compacted in order to improve its flow rate properties.
The homogenous mixture does not have to be processed into jackets immediately
as long as no heat
is applied to the mixture.
The end of the internal punch of the jacket forming die may be flat or
slightly hollow. If the end of
the internal punch is flat, a flat base projectile will be formed, if the tip
of the internal punch is
hollow, a boat-tail projectile will therefore be formed.
The external punch of the jacket forming die will be tapered accordingly at
its end in order to form a
suitable cavity within the jacket. Any variance in the taper will create
jackets that have different
properties, for example variance in strength and weight.
A suitable amount of homogenous material is placed in a jacket forming or
swaging die having a
specified cavity diameter. The diameter of the jacket forming die will have a
diameter less than the
final diameter of the completed projectile in order to allow for any expansion
of the formed jacket
after curing. Typical expansion of the frangible jacket after curing is about
.005 of an inch. It is
therefore necessary to make the frangible jacket slightly smaller in diameter
in order to allow for
this expansion.
After a pre-determined amount of homogenous material is placed in the jacket
forming die, the
material is compressed or swaged within the jacket forming die. The applied
pressure may vary
between I to 50 tons depending on the diameter of the jacket being formed.
After the jacket is formed, the jacket is heated or cured to the desired
hardness or frangibility. FIG. I
illustrates the frangible jacket 1 constructed with metal particles 3 mixed
with cured liquid natural
rubber 2.
It should be noted that is important that any projectiles of this invention
made with frangible jackets
of the described type have enough strength to withstand the forces created
when shot out of a rifle
having a rifling twist of 7 to 1. If the jacket of the above description is
too frangible, the projectile
will fracture while travelling through such a rifled barrel.
Also, the frangible jacket lips 9 should have enough flexibility in order to
be bent at least 20 degrees
to a maximum of 45 degrees. The ability of the frangible jacket to be bent in
such a fashion will be
useful in locking any core that is seated inside it. This will prevent any
core seated inside the
frangible jacket from becoming loose and effect accuracy in a negative way.
It was found that there are many factors that may influence the frangible
jacket from having the
required flexibility and frangibility.
CA 02613696 2007-12-10
-5-
A) metal particles utilized
A) amount of curable liquid natural rubber mixed
B) forming pressure
C) amount of dry lube
D) curing time
E) curing temperature
The internal core of the current invention is made with metal particles that
are blended with curable
liquid natural rubber. Metals particles such as copper, bronze, brass, tin,
zinc, iron, tungsten and
bismuth are examples of suitable metal particles that can be utilized in the
formation of the
frangible bullet core. The metal particles may be powder, flakes or chips and
a combination thereof.
The liquid natural rubber should have a viscosity similar to skimmed milk to
be most effective.
There are suitable thinners that can be used to make the natural liquid rubber
less viscose if desired.
Metal particles are mixed with a pre-determined amount of natural liquid
rubber and 30 to 1 is a
typical weight ratio of metal particles to liquid natural rubber. A suitable
liquid rubber thinner may
be added to the homogenous mixture if desired.
After the homogenous mixture of metal particles and liquid natural rubber are
mixed and all the
volatiles of the liquid natural rubber have completely evaporated, a suitable
dry lube is added to the
dried homogenous mixture and .5% is a typical amount that is used.
The homogenous mixture of metal particles, the dried liquid natural rubber and
dry lube may be
roller compacted in order to improve its flow rate properties.
The homogenous mixture does not have to be processed into bullet cores
immediately as long as no
heat is applied to the mixture.
It should be noted that it is desirable that the frangible bullet core be
weaker and substantially less
flexible than the frangible bullet jacket. By increasing the liquid natural
rubber ratio from 60/1to30
/1, the desired weaker core will be attained. It should also be noted that the
density of the frangible
core may not necessarily have the same density of the frangible jacket. Some
core densities may be
more suitable than other densities in certain applications. Densities are
adjusted accordingly by the
type of metal particles utilized, the amount of natural liquid rubber used and
by the amount of
pressure applied during the core swaging stage.
After a pre-determined amount of homogenous material is placed in the core
forming die, the
material is compressed or swaged within the core forming die and the desired
shape is attained. The
desired shape of the frangible bullet core should be close to the internal
dimensions of the cavity
within the frangible bullet jacket in which the cores will be inserted in. The
amount of pressure
applied for core manufacturing will be dependent on the frangible core
diameter and the final core
density that is required.
CA 02613696 2007-12-10
-6-
After the frangible cores are formed, the cores may be cured if desired. When
the frangible cores are
cured, the frangible cores will be slightly hardened which therefore may be
more desirable in most
applications. In most applications, the curing time for the core will be less
than the curing time for
the jacket and also the curing temperature will be less than the curing
temperature of the jacket.
FIG.2 shows frangible core 4 constructed of metal particles 5 blended in cured
liquid natural rubber
6.
FIG.3 shows seated frangible core inside frangible jacket
FIG. 4 shows completed frangible projectile.
The current invention teaches that bullet manufacturing is achieved by
utilizing conventional
equipment.
Bullets manufacturing steps:
A) frangible jacket drops inside conventional bullet seating die
B) frangible core is inserted inside cavity of frangible jacket
C) frangible core is compressed or seated inside frangible jacket
D) seated frangible core and jacket are extracted from bullet seating die
E) seated frangible core and jacket are dropped inside conventional point-
forming bullet die
F) frangible projectile is formed in a conventional manner
G) frangible projectile extracted from point-forming bullet die
H) frangible projectile is polished and loaded into ammunition if desired.
Example
A frangible bullet jacket was formed using metal particles mixed with 60 to 1
ratio by weight of
curable liquid natural rubber. The weight of the jacket was recorded to be 85
grains, the diameter
was .307 of an inch after curing.
A corresponding frangible core was formed using metal particles mixed with 30
to 1 by weight of
curable liquid natural rubber. The weight of the frangible core was 35 grains
after curing.
The frangible jacket and frangible core were formed into a 30 caliber
projectile using conventional
equipment. The total weight of the projectile was 120 grains. The projectile
was loaded into a 30-06
casing and fired at a 10" by 10" AR500 steel plate at distance of 10 feet. The
velocity was recorded
to be 3115 feet per second and the twist of the barrel used was 1 to 7.
It was noted that there was no damage to the plate and the projectile broke up
into very small pieces
with no splash back of particles towards the shooter. Before the projectile
struck the steel plate, the
CA 02613696 2007-12-10
-7-
projectile had to penetrate a clear sheet of paper. There was no evidence on
the paper that the
projectile had broken up in any fashion while passing through the barrel of
the firearm.
