Note: Descriptions are shown in the official language in which they were submitted.
- 1
2 1337962
COMPOSITE CARTRIDGE FOR HIGH VELOCITY RIFLES AND THE LIKE
g BACKGROUND OF THE INVENTION
This invention relates to improvements in the ammunition art,
11 and specifically to improvements in the ammunition of the type
12 used in high power rifles of all calibers in which an elastomer
13 or plastic is used for a predo~;nAnt portion of the casing which
14 houses the powder and positions the projectile. The casing is
made of a synthetic polymer composition attached to a metallic
16 head positioned at the opposite end of the cartridge from the
17 projectile.
18
19 Cartridges of this general type have been known in the
literature for many years but have for one reason or another,
21 failed to provide a satisfactory ammunition for sustained
22 automatic fire in the modern automatic weapons widely used in
23 police, paramilitary and military situations.
24
26
27
28
s.
-2- 1337962
The following patents are known to disclose various types of
composite cartridges of the general type to which this invention
is addressed:
UNITED STATES PATENTS INVENTOR
2,654,319 Roske
7 2,826,446 Ringdal
3,026,802 Barnet et al.
8 3~099~958V Daubenspeck, et al.
3,745,924 Scanlon
9 3,842,739 (unknown)
3,874,294 Hale
3,977,326 Anderson
4,147,107 Ringdal
11
UNITED KINGDOM
12 1,015,516 Daubenspeck et al.
GB2,044,416 Application Hebert
13
EUROPEAN PATENT APPLICATION
14 0 131 863 (Publn. 23.01.85) Vatsvog
GERMAN PATENT
2,419,881
16
Cartrldges of this type are also used in large quantities as
blank rifle cartridges in which the head end of the cartridge
18
case continues into the imitation shape of a plastic projectile
19
which constitutes an integral part of the cartridge case and has
a notch or groove forming a predetermined rupture zone. these
21
cartridges are loaded with a no~;n~l amount of powder and are
22
used as training and simulation aids without a projectile of the
23
usual type. Because of the nom; n~ 1 loading of powder,
24
cartridges of this type may not develop enough chamber pressure
to operate the gas-operated automatic ejection and reloading
mechanisms used in military type automatic weapons.
27
28
.
~3~ 13~7962
1 It is recognized that a plastic rifle cartridge should usually
2 have a metal cap or head to carry the primer and to provide the
3 ejection groove necessary to eject the spent cartridge from the
4 firing chamber. When used in a modern automatic weapon the need
is also present for a reinforced cap or head area to contain
6 residual pressures in the cartridge occasionally encountered
7 when the ejection cycle begins removal of the cartridge from the
8 chamber before the pressure effects of the recent firing have
g fully dissipated. To achieve consistent performance, both
ballistically and in the operation of the gas operated ejection
11 mechanism, a rifle cartridge must develop a consistently high
12 chamber pressure level for each round. Heretofore, the
13 attainment of consistent pressure levels has been difficult, due
14 to inconsistencies in the interfit between the bullet and the
cartridge, improper sizing of the powder chamber for the powder
16 used, and to the many variations in the performance in the
17 burning cycle of the various powders available for use in rifle
18 ammunition.
19
Conventional cartridges for rifles and machine guns, as well as
21 larger caliber weapons are usually made with brass casings. The
22 brass casing includes an integrally formed head containing a
23 primer cup to receive a primer adapted to ignite a powder charge
24 at one end, and at the other end provides a mechanical interfit
to a bullet. The grip of the cartridge upon the bullet,
26 together with the amount and characteristics of the powder, the
27 interior volume of the powder chamber and other factors
28
1337962
-- 1 determine the chamber pressure levels developed during the
2 firing cycle. The bullet or other projectile is held in place
3 with a crimp or frictional engagement, the strength of which is
4 a factor in determining the pressure needed to initiate bullet
movement into the barrel of the rifle. Brass casings can be
6 reloaded and thereby reused but suffer from several
7 disadvantages, including weight. In addition, special tooling
8 is necessary for reloading. Brass is also a relatively
g expensive metal which may be in short supply in some areas of
the world, particularly in the event of war.
11
12 Expendable aluminum casings have been developed but generally
13 are not reusable, making the ultimate cost of the aluminum
14 casing comparable to brass. An extensive amount of precision
metalworking equipment is necessary to form the casings from
16 either brass or aluminum.
17
18 Several attempts have been made to develop a reusable handgun
19 casing made of lightweight plastic materials, including my
successful development described in my European Patent
21 Application No. 0 131 863. In the use of plastic casings of the
22 prior art, it is necessary that there be a tight fit between the
23 casing and the bullet and between the casing and the head in
24 order to prevent the escape of the gases formed when the powder
charge is ignited. These gases in the handgun loads can quickly
26 reach a pressure of over 10,000 psi, and thus the seal around
27 the bullet and around the head must be tight enough to prevent
28
~5~ 1337962
~ 1 the escape of the gases until the bullet is discharged. In
2 rifle applications, such as the NATO 5.56 mm (.223 caliber)
3 widely used in weapons such as the M-14 and M-15 used by the
4 United States of America and its allies and various 5.56 mm
rifles used by Warsaw pact forces pressures of 40,000 to 60,000
6 psi or higher may be encountered. The seal around the head is
7 of extreme importance at these higher pressures as well as the
8 strength of the head extending along a substantial distance of
g the side wall of the cartridge to prevent rupture of the
sidewall of the cartridge during ejection of the spent
11 cartridge. Such a rupture and escape of the gases would not
12 only adversely effect the performance of the bullet being
13 discharged but would also potentially adversely affect the
14 subsequent firing of the rifle and could present a safety hazard
to the rifleman or his companions.
16
17 f great significance is the need to controllably maintain the
18 chamber pressure developed by detonation or burning of the
19 powder during the firing cycle so that a consistent pressure
level is attained for a given powder load and type. In brass
21 cased ammunition the pressure level is attained during and
22 following burning of the powder in part through the crimp or
23 frictional interfit between the bullet and the inner wall of the
24 case. With plastic cases the control of the pressures has
heretofore been erratic and unacceptable.
26
27
28
` -6- ~ 1337962
1 For military rounds, the need for reloading capability is
2 m; nimi zed, so long as the round is relatively inexpensive to
3 manufacture and load, and so long as the other desirable factors
4 of the cartridge, such as corrosion resistance, weight, moisture
resistance and the like provide a cartridge as dependable as
6 brass
8 Brass cartridges rely upon the crimp or frictional engagement
g with the bullet to control the buildup of pressure before bullet
ejection. A more consistent and reliable control would provide
11 more nearly consistent ballistics performance and is one of the
12 attributes of this invention.
13
14 In all of the patents mentioned above the cartridge is formed of
a composite plastic or metal and plastic casings which rely on
16 multiple parts to provide the sealing around the end caps or
17 head, and require a crimp about the bullet to hold the bullet in
18 place. The cost of producing and assembling a multiple piece
19 casing is high and heretofore the composite casings have not
20 accomplished the dual functions of sealing the head to the
21 plastic casing and the plastic casing to the bullet in a manner
22 which permits the resulting cartridge to be used in fully
23 automatic rifle firing applications.
24
26
27
28
1337962
1 DISCLOSURE OF THE INVENTION
3 It is an object of this invention to provide a lightweight
4 plastic composite cartridge for use in high velocity rifle
applications in which the pressure developed by ignition of the
6 powder is controlled.
8 It is another object of the invention to provide a cartridge for
g rifle ammunition which can be used in fully automatic weapons.
11 Another object of this invention is to provide a cartridge which
12 has a frangible pressure control bulkhead or partition which
imparts pressure and force against the base of the bullet after
14 a threshold level of pressure is attained to assure optimum
powder ignition and complete burning.
16
A still further object of this invention is to provide
18 ammunition in a cartridge in which the bullet can be inserted or
19 removed easily without exposing the powder.
21 One further object of this invention is to provide a cartridge
22 for rifle use which can have its powder load inserted from the
23 base or head end of the cartridge without the presence of the
24 bullet.
26 Another object of this invention is to provide a cartridge for
27 use in a rifle which has a light frictional interfit with its
28
1337962
bullet and no crimp or its equivalent to hold the bullet in place,
for smooth and reproducible ejection of the bullet from the
cartridge upon firing.
The present invention employs a tubular plastic casing
made of a durable but elastic plastic material such as nylon which
has the structural integrity to remain intact around the area upon
which a malleable skirt is swaged to form the interconnection
between the plastic casing and the head. The casing is formed by
injection molding a relatively simple shape which may have draft
angles built in to permit easy removal of the part from the male
mold part. In the process of molding a partition or pressure
control septum is molded in at the bullet-receiving end of the
casing to define a bullet receiving recess and a powder receiving
recess. A metal head is formed to slip on the end of the casing
opposite the bullet receiving recess and be swaged into faired
contact with the periphery of the casing in a sealed joint.
Alternately, the head may be swaged prior to assembly and the
elastomer casing forced into the head, the elastomer material
being yieldable but possessing plastic memory sufficient to urge
it toward its original shape and into firm contact with the
interior surface of the head. The head has a primer recess into
which a primer may be inserted coaxially with the head and casing.
A primer flash hole or central vent extends coaxially into the
powder chamber to ignite the powder upon detonation of the primer.
The powder chamber is defined by the plastic casing, the pressure
regulating frangible partition and by the head when it has been
inserted axially over the casing and the skirt or a part thereof
swaged into a fared interlock with the casing or into a
B
- 1337962
9 74158-5
circumferential groove. The volume of the powder chamber may be
varied according to the type of powder being used so that the
- powder used fills the chamber to simplify loading and to optimize
the burning characteristics of the powder. The pressure
regulating front partition preferably is thickened from the
frangible annular periphery thereof toward the cartridge axis in a
semi-spherical configuration to provide application of forces
evenly across the base of the bullet. The frangible partition
functions to separate the powder chamber from the bullet
receptacle, to seal the powder chamber at the forward end thereof
and to provide a controlled pressure rupture threshold to
controllably regulate the generation of pressure during the firing
cycle so that the power of the powder is both maximized and
controlled by regulating the pressure level at which the
projectile begins to move. The strength of the frangible annulus
is tailored to the powder type and charge to provide the optimum
powder burn cycle by increasing or decreasing the thickness during
molding and by choice of the elastomer used.
More particularly the invention seeks to provide a
cartridge comprising: a plastic casing molded from a reinforced
high impact plastic, æaid casing having a bullet end and a head
end, said bullet end having a substantially cylindrical bullet
receiving recess adapted to receive a bullet in a frictional
engagement and having a pressure regulating front partition
separating said bullet recess from a powder chamber, said pressure
regulating front partition being molded integrally with said
casing and having a frangible annulus positioned at the juncture
between said partition and said casing, said annulus having a
`- 1337962
9a 74158-5
substantially uniform thickness around its periphery of from 0.010
to 0.020 inches whereby said partition resists removal thereof
until a predetermined pressure is achieved in said chamber by an
ignited powder charge; an external interlock surface at said head
end; a cartridge head having a casing engaging recess at one end
thereof and a primer receiving recess in the other end thereof,
said casing engaging recess receiving said external interlock
surface of said casing therein and extending toward said bullet
receiving end around the outside of said external interlock
surface and fairing with said casing, whereby pressure generated
by detonation of a powder charge in said casing forces said casing
outwardly into gas sealing relationship with said cartridge head
casing engaging recess and whereby said head reinforces and
prevents sidewall blowout of said casing during extraction of said
cartridge from an automatic fire weapon.
The invention also seeks to provide a method of
manufacturing a rifle cartridge comprising the steps of: molding
a substantially cylindrical plastic cartridge having a bullet
receiving end forming a bullet recess; an open, head receiving end
with a circumferential head interlock surface thereon; a casing
axially disposed between said ends with a thickened shoulder
formed therein; and a pressure regulating front partition
extending across the casing separating the bullet recess from a
powder chamber at said thickened shoulder, said partition having a
frangible annular zone designed to be severed cleanly completely
around the periphery thereof; forming a cartridge head having a
coaxial primer recess and a coaxial casing receiving recess, said
casing receiving recess comprising a deformable skirt adapted to
9b 1337962 74158-5
be swaged into contact about said circumferential head interlock
surface; placing a charge of gunpowder in said casing; placing a
primer in said primer recess; assembling said casing and said
head; and, swaging said deformable skirt about said head interlock
surface to firmly interconnect said casing and said head.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows an exploded perspective view of the
composite cartridge of this invention for use with a boat tail
bullet.
B
-lo- 1337962
~- 1 Fig. 2 shows one embodiment of this invention with the casing
2 and head in cross section.
4 Fig. 3 is a partial cross sectional view of a second embodiment
of the cartridge of this invention for use with a flat base
6 bullet.
8 Fig.4 is an enlarged axial cross sectional view of the cartridge
g shown in Fig. 1.
11 Fig 5 is an enlarged axial cross sectional view of another
12 embodiment of this invention.
13
14 Fig. 6 is a cross sectional view of the partially manufactured
15 metallic head useful in one embodiment of this invention.
16
17 Fig. 7 is a cross sectional view of the device shown in Fig. 6
18 after a extraction groove cutting and forming step.
19
Fig. 8 is a cross sectional view of the device shown in Fig. 7
21 with an adhesive material applied to the interior surface
22 thereof.
23
24 Fig. 9 shows a cross sectional representation of the final
25 assembly step to unite the plastic casing to the metallic head
26 in one embodiment of this invention.
27
28
37 9 6 2
1 DETAILED DESCRIPTION
-- AND BEST MODE FOR CARRYING OUT THE INVENTION
Referring particularly to the drawings where in like figures
indicate like parts, there is seen in Fig. 1 an exploded view of
one embodiment of this invention. A rifle cartridge suitable
for use with high velocity rifles is shown manufactured with a
polymer case 12 and a metallic head 14. A bullet 10 having a
circumferential groove 60 is shown positioned for insertion into
the forward end of plastic casing 12. A pressure regulating
front partition 44 (best seen in Figs. 2 through 6) securely
closes off the forward portion of outer chamber 36 and is
11 adapted to receive the base 61 of bullet 10. The forward
12
portion of casing 12 has a thickened shoulder 42 forming chamber
13
taper 40. The shoulder 42 supports a frangible annular zone 48
14
which is engineered and designed to be severed cleanly
completely around the periphery of the shoulder 42 when
16
sufficient pressure is developed on the interior of powder
17 chamber 36. The pressure regulating front partition 44 has a
18
semi cylindrical surface projecting rearwardly into the powder
19
chamber 36 to aid in the even distribution of pressure to the
bullet 10 upon detonation of the powder charge 38 contained in
21
chamber 36. The frangible annulus 48 is sized in thickness to
22
provide the desired level of pressure before bursting so that a
23
controlled powder detonation can occur and further to provide
24
the more nearly controllable pressure application to the base of
bullet 10. The presence of the pressure regulating front
26
partition 44 is made possible by the composite configuration of
27
28
-12- 1337962
1 the cartridge. The front partition 44 is molded as a part of
2 and extends inwardly from shoulder 42. The interior volume of
3 powder chamber 36 may be varied to provide the volume necessary
4 for complete filling of the chamber 36 by the powder chosen so
that a simplified volumetric measure of powder can be utilized
6 when loading the cartridge.
8 The end of plastic casing 12 opposite from the pressure
g regulating front partition 44 has means to engage and seal to a
metallic head 14. Casing 12 is formed with a tapered skirt
11 interlock surface 30 adapted to mate with and interlock with the
12 deformable skirt 20 of head 14. The skirt interlock surface 30
13 preferably tapers from a larger diameter at the rearward most
14 portion 64 thereof to a smaller diameter at the forward portion
65. A swaging anvil 22 may be used to provide backing for
16 swaging of head 14 onto plastic casing 12. Anvil 22 is received
17 within anvil recess 32 and provides support for the plastic
18 casing 12 during the swaging process. Chamfers 24 are provided
19 for ease of insertion of the anvil into the casing.
21 Head 14 is formed in a high pressure head forming apparatus as
22 is well known in the prior art. However, the die used provides
23 for a diverging deformable skirt 20 having a larger diameter at
24 the skirt tip 54 and a relatively smaller diameter,
approximating the outside diameter of head 14 at the skirt base
26 56. The thickness of skirt 20 increases from skirt base 56 to
27 skirt tip 54 so that when swaged into contact with the tapered
28
-13- 1337962
~ 1 skirt interlock surface 30 a faired substantially cylindrical
2 surface along the entire length of the assembled cartridge will
3 result with a physical interlock between head 14 and plastic
4 casing 12. Head 14 also has an extraction groove 26 cut therein
and a primer recess 18 formed therein with primer chamfer 29 for
6 ease of insertion of the primer 16. The primer recess 18 is
7 sized so as to receive the primer 16 in an interference fit
8 during assembly. A primer flash hole 28 communicates through
g the anvil central vent 34 into the powder chamber 36 so that
upon detonation of primer 16 the powder in powder chamber 36
11 will be ignited. An alternative structure would include a
12 groove at portion 65 to receive a swaged tip section 54 in a
13 head configuration without the flared skirt configuration
14 described above.
16 Bullet 10 is held in place within bullet recess 50 by a
17 frictional interfit. The bullet may be inserted into place
18 following the completion of the filling of powder chamber 36 and
19 final assembly of the cartridge by swaging the deformable skirt
20 into contact with the tapered skirt interlock surface 30. In
21 this way bullets of differing size and characteristics can be
22 utilized and may even be interchanged without affecting or
23 exposing the powder in powder chamber 36.
24
Whenever a flat bottom bullet is used the configuration shown in
26 Fig. 3 may be used to accommodate the particular bullet shape
27 desired. In this embodiment the shoulder 42' is formed with a
28
-14- 1337962
- 1 smaller interior angle from the axis to accommodate the full
2 diameter of bullet 11'. The flat base 61' rests against the
3 pressure regulating front partition 44' which is configured with
4 a larger diameter so that the entire base 61' receives the
pressure developed within chamber 36'.
7 When it is desired to have a larger volume in powder chamber 36,
8 the configurations shown in Figs. 5 and 6 through 9 may be
g utilized. In Fig. 5 the anvil (shown as 22 in Fig. 4) is
omitted with the deformable skirt 20 being swaged carefully
11 against the surface of casing 12. Omitting the anvil permits a
12 larger charge of powder to be placed into the casing. The
13 thickness of the plastic casing 12 and shoulder 42 can also be
14 varied so that the volume of powder chamber 36 can be modified
for various powder types and loads to provide a consistent
16 performance with any given powder.
17
18 Another alternative embodiment is shown in Figs. 6 through 9 in
19 which the head 114 is formed and the deformable skirt thereof
swaged prior to assembly with the plastic casing 112. As seen
21 in Fig. 6, the head 114 is formed by known head forming
22 techniques into the shape as shown with the deformable skirt 120
23 having a substantially cylindrical interior and a diverging
24 exterior surface as shown. The interior diameter b is formed so
that the device may be removed from the die and the exterior
26 surface diverges outwardly to the diameter c. Annular extractor
27 groove 126 is then cut into the formed head and the deformable
28
_ 15 ~337962 74158-5
skirt is swaged into the condition shown in Figure 7 with the base
of the recess to receive the plastic casing having an interior
diameter b and the throat of the recess to receive the casing
having an interior diameter e. A chamfer 66 is provided to guide
and press inwardl~ the end of t,he plastic cartridge 112 as is
further described below. A primer recess 116 and flash hole 128
are also formed in head 114 at the time it is formed.
In Figure 8 an adhesive 68 is shown spread on the
interior surface of the casing recess 115. The adhesive 68 is
preferably a contact type cement compatible with the metal forming
head 114 and the plastic material forming plastic casing 112.
Figure 9 shows the assembly step following completion of the head
and filling of the powder chamber 36 with powder. Head 114 is
positioned coaxially with the filled plastic casing 112 and the
elements are moved axially together, forcing the rounded end 70 of
plastic casing 112 into recess 115 until the rounded ends 70 abut
upon the base 72 of recess 115. When assembled the elastic memory
of casing 112 will cause the end 70 of casing 112 to expand and
contact the interior of recess 115 in a tight interference fit.
The diameter of rounded end 70 at portion 74 is shown in Figure 9
as being equivalent t,o the interior diameter of recess 115 at the
base thereof and larger than the diameter of portion 75. As a
result the plastic casing firmly contacts the adhesive 68 forming
a secure mechanical and water tight bond to hold the elements of
the completed cartridge together. In each embodiment set forth
above, the deformable skirt 20 or 120 extends far enough up the
side of the casing to provide casing strength preventing blow out
of the side of the casing during rapid automatic fire. The
~'
- 16 1337962 74158-5
adhesive is optional and may be omitted under circumstances in
which the interfit between head and plastic casing is found to be
adequate without the adhesive being used.
The experienced handloader or ammunition manufacturer
will know that many powder types and weiqhts can be used to
prepare workable ammunition and that such loads may be determined
by a careful trial including initial low quantity loading of a
given powder and the well known stepwise increasing of a given
powder loading until a maximum acceptable load is achieved.
Extreme care and caution is advised in evaluating new loads. The
powders available have various burn rates and must be carefully
chosen so that a safe load is devised. The following examples
show some of the stepwise progression of loads undertaken by the
inventor to establish the acceptable chamber pressures, bullet
velocities and performance at this inventor's present stage of
development which reflect workable and usable ammunition.
Example 1. A cartridge of the type shown in Figure 4
for use with the 5.56 ml. NAT0 (.223 caliber) high velocity rifle
was prepared as follows: A 55 grain boat tail full metal jacket
bullet was used of the type shown in Figure 1. The plastic casing
12 was formed from an unpigmented DuPont 901 super tough ST nylon
available from E.I. DuPont, Willmington, Delaware. The pressure
regulating front partition 44 was formed using a frangible annulus
48 having a thickness of 0.020 inches. 21.4 grains of Hodgedon H-
*
335 spherical powder, having a moderate burn rate was used. ACCI small rifle magnum primer manufactured by CCI Industries was
inserted into the primer recess. The round was fired through a
*
Trade-mark of E.I. DuPont de Nemours & Co.
17 1337962 74158-5
5.56 mm ~.223 caliber) pressure barrel with 1 in 7 twist,
manufactured by Obermeyer Rifled Barrels attached to a universal
receive to determine the pressure developed in the chamber when
fired. A pressure of about 45,000 psi was measured using the
standard copper crush test.
Example 2. A cartridge identical to that described in
Example 1 was prepared using 18.7 grains of Hodgedon H-335 with a
pressure regulating front partition 44 having a frangible annulus
with a thickness of 0.010 inches. A chamber pressure of 30,000
psi was observed upon firing.
Example 3. Cartridges loaded in accordance with Example
1 were fired in a semi-automatic rapid fire mode in a .223 caliber
semi-automatic rifle to evaluate the ejection of spent cartridges
and performance. Thirty rounds were loaded into a clip and fired
as rapidly as possible in the semi-automatic mode. All 30 rounds
were fired and were ejected successfully from the automatic
ejection mechanism.
Example 4. Ten cartridges constructed as shown in
Figures 1, 2 and 4 were constructed using a head 14 made of 1010
steel alloy.
Trade-Mark
18 1 3 3 79 6 2 74158-5
A CCI small rifle magnum primer was placed into the primer recess
and 21.4 grains of BL-C-(2)* powder, which is a rapid burning
powder, was placed into the powder chamber 36. The swaging anvil
22 was placed into the open end of the powder chamber 36, and the
head 14 was carefully swaged about the exterior of the plastic
casing 12. The outer surface of the cartridge was smooth and
faired at the intersection of the metal cap and the plastic case.
A 55 grain full metal jacket spire point boat tail bullet was
inserted into the bullet recess. The plastic casing had a
pressure regulating front partition having a frangible annulus
with a thickness of 0.020 inches. The round was fired in a
universal receiver with the .223 caliber barrel manufactured by
Obermeyer attached thereto. When discharged the rounds developed
chamber pressures in the range of 38,000 to 40,000 psi and were
grouped in a 2 inch diameter circle upon a target set at 50 yards.
Example 5. Several rounds identical to those described in
Example 4 were prepared using 21.4 grains of Hodgedon H-335*
powder. When fired the rounds developed a cylinder pressure of
43,000 to 45,000 psi.
Example 6. A round identical to those described in Example 4
was prepared but using a front pressure regulating partition
having a frangible annulus thickness of 0.010 inches. 21.4 grains
of BL-C-(2)* powder developed 33,000 psi chamber pressure when
discharged.
* Trade-mark
19 1 337 9 6 2 74158-5
Example 7. A round identical to the round described in Example
6 was prepared but with a front pressure regulating partition
having a frangible annulus of 0.020 inches thickness. Upon
discharge the round developed 43,000 psi chamber pressure.
Example 8. A round identical to the round described in Example
6 was prepared using 21.4 grains of Hodgedon H-335* powder. When
discharged the round developed 33,000 psi chamber pressure.
Example 9. A round was constructed using the procedure and
structures shown in Figures 6-9. Low nitrogen content series 1010
steel was fed into a heading machine to form the head precursor
form shown in Figure 6. The dimensions shown were as follows:
a = 0.376 inches
b = 0.355 inches
c = 0.398 inches
d = 0.375 inches
e = 0.334 inches
Bevel 66 was formed at about 30 degrees from the axis of the head
114. The ejection groove 126 was then cut into head 114 and the
skirt 120 swaged inwardly so that the outer surface of the head
114 was cylindrical along its entire length. An adhesive
material, sold under the trade designation PRONTO-LINE CA-9*, a
product of 3M Corporation, Minneapolis, Minnesota, was sprayed
upon the interior of head 113 to form a band of adhesive 68, the
adhesive was permitted to dry for 15 minutes. 21.4 grains of
Hodgedon H-335* powder was placed into a vertically oriented
plastic casing having a pressure regulating front partition with a
frangible annulus thickness of 0.020 inches. The head 114 was
A * Trade-mark
~ 20 1337962 74158-5
positioned above the plastic casing as shown in Figure 9 and
quickly and firmly thrust over the rounded upper end of casing
112, firmly seating the cap fully upon casing 112. Since the
diameter b of the upper end of casing 112 exceeds the inside
diameter e of head 114, the casing end was slightly deformed
inwardly toward the axis and upon full engagement of the parts was
returned to its former configuration due to the plastic memory of
the casing material. The adhesive material then engaged the
plastic surface to form a structural and watertight bond. A 55
grain spire point boat tail full metal jacket bullet was then
inserted into the bullet recess and the cartridge fired in the
universal receiver having a 20 inch .223 caliber barrel noted
above. The round developed 44,000 psi chamber pressure and the
bullet hit its intended target at 50 yards.
Example 10. A test firing of twenty five cartridges
manufactured and loaded as set forth in Example 4 with 18.0 grains
of IMR 4198* powder with a comparison to factory ammunition was
conducted by H.P. White Laboratory, Inc. 3114 Scarboro Road,
Street, Maryland 21154. The ammunition tested was hand loaded by
the inventor and was designated as 5.56 mm plastic case with a 55
grain Sierra FMJBT* bullet. The rounds were compared to 10 rounds
of a conventional brass cased
A * Trade-mark
-21- 13 379 62
- 1 ammunition prepared and sold by Olin Corp., Winchester Division
2 in 5.56 mm with a 55 grain FMJ bullet. All rounds tested were
3 fired in a NATO pressure barrel, H.P. White Serial No. 10,
4 having a barrel length of 20 inches. The velocity and chamber
pressure results are set forth below:
7 PLASTIC CASE WITH PRESSURE REGULATING PARTITION
8 ROUND NO. VELOCITY PRESSURE
fps psi
1 2812.1 51,800
2 2g07.8 58,400
3 2914.1 58,800
11 4 2896.4 57,200
2923.1 55,600
12 6 2953.7 58,000
7 2946.8 61,300
13 8 2908.2 58,000
9 2960.7 64,100
14 10 2954.2 64,400
11 2857.9 54,000
12 2966.9 64,100
13 2942.4 59,600
16 14 2947.2 61,600
2998.5 66,900
17 16 2988.6 64,100
17 2942.0 60,600
18 18 2940.3 62,500
19 2933.8 59,600
19 20 2967.3 61,900
21 2911.6 60,300
22 2912.0 58,800
23 2970.0 61,900
21 24 2896.0 58,400
2974.4 61,300
22
Average 2933.0 60,100
23
Std. Dev. 40.3 3,368
24
26
27
28
` -22- 1337962
1 FACTORY LOADS
2 ROUND NO. VELOCITY PRESSURE
fps psi
1 3159.0 49,900
4 2 3194.8 48,000
3 3160.5 47,600
4 3171.5 45,900
3153.5 45,400
6 6 3162.5 45,900
7 3136.2 45,000
7 8 3187.2 47,600
9 3190.3 47,100
8 10 3200.5 47,100
g Average 3171.6 47,000
Std. Dev. 19.78 1,382
In compliance with the statutory requirements, the invention in
12 various embodiments has been described in language more or less
13 specific as to structural features and methods to enable one of
skill in this art to practice the invention. It is to be
understood, however, that the invention is not limited to the
16 specific features and methods shown and described, since the
means and constructions herein disclosed comprise a preferred
form of putting the invention into effect. The invention is,
19 therefore claimed in any of its forms or embodiments within the
legitimate and valid scope of the appended claims, appropriately
interpreted in accordance with the doctrine of equivalence.
22
23
24
26
27
28
