CA1052179A - Cased ammunition - Google Patents

Abstract

IMPROVED CASED AMMUNITION

ABSTRACT OF THE DISCLOSURE

A round of case ammunition is provided employing a con-solidated smokeless powder charge. The consolidation of the smokeless powder charge permits higher loading density of the cartridge case and results in improved ballistic performance for a given round of cased ammunition.

Description

Burkhalter and Peterson Case 1 This invention relatPs to a consolidated charge for cased ammunition and a method of making said consolidated charge.
More particularly, thi~ invention relates to a round of cased ammunition in which the propellant comprises a porous consoli- -dated charge.
Standard cased ammunition utilizes a loose powder charge, which is usually in granular or small ball form. The loading density for charges prepared from propellant granules is about 0.9 grams per cc. and loading density for charges prepared from ball powder is about 0.95 grams per cc. In accordance with this invention, the loading density of cased ammunition can be substantially increased, thus making it possible-to increase the propellant charge weight within the confines of the cartridge case and thus substantially increase available energy for the charge. ~;~
I Consolidated charges are not new, in fact they have been known for many years. For example, U.S. Patent 321,042 describes ` a propellant charge formed of powder compacted into a cake within 1, a cylindrical shell or case, the powcler cake is solid. U.S.
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Patent 392,922 relates to a charge for cased ammunition in which the powder forming the charge is pressed practically into a solid mass with a centrally situated conical or cylindrical cavity ~hrough the charge. U.S. Patent 846,612 relates to cartridge cases loaded with charges comprised of sheets or strips of smoke- 1 less powder. V.S. Patent 1,010,430 describes a shell having an explosive charge which consists of a main charge of explosive material in the ~orm of a cast homogeneous solid.
The consolidated charge employed in the cased ammunition , ,;1 . . ~
~¦ of this invention, however, represents a distinct improvement over ~, the consolidated charges employed in cased type ammunition such as heretofore described. The consolidated charge employed in this , invention comprisès a compaction of granules of smokeless powder `~ having a multiplicity of interstitial spaces substantially uni-;` formly distributed throughout the compacted mass. The intersti~

tial spaces are formed as a result of compacting randomly .:

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oriented7 cylindrically or ball shaped granules. In preparing ~hes~ porous consolidated charges, the surfaces of the individ ual granules are first softened by exposure of the granules to sol~ent vapors and then pressed together~ This consolidated charge provides the advantages of the p~ior art consolidated charges, iOe~, it is ~elf-supporting and has high density, but retains the advantages of a loose granular charge in that the consolidated charge will burn upon ignition by a primer as if it were a loose granular charge. The consolidated charge must be porous to pernit flame spread throughout the charge upon ignl-tion~ While not bound by any theory, it is believed that the consolidated charge breaks up into individual granules under the influence of the ignited primer and/or chamber pressure to burn similarly to a loose granular charge.
According to the present invention there is provided in a round of cased amm~nition comprising a projectile and a metal cartrldge case having an internal cavity for holding a propellant charge, and a propellant charge held wi~hin said cavity in the metal cartridge case, the improvement comprising - 20 a self-supporting~ consolidated, porous propellant charge pre-pared by a process comprising wettillg smokeless powder granules ~
with a solvent ~or the nitrocellulose component of said gra~ules, ;
said solvent being employed as a vapor, said wetting being Gon; -tinued for a time sufficient ~or said smokeless powder granules to contain from about 2~o to about ~ by weight of solvent, con-solidating said solvent-wet granules at a pressure of from ~00 p~s.i. to 5000 p.s~i. whereby the granules are~`compacted to form ~` a self-supporting charge, said granules being compacted up to ; 6~ o~ their original nonco~pacted volume~ and heat curing the ~ -resulting consolidated charge.
The cased ammunition of this invention is more ~ully !.~` , .
described with reference to the drawings which follow. In the

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drawings like numbers refer to like parts where applicable.
Figure l is a schematic view partly broken away and partly in section of a cartridge case loaded with loose granules of smokeless powder, as is typically done in the prior art.
Figure 2 is a schematic view partly broken away and partly in section of a cartridge case in which a propellant charge equivalent in weight to the charge shown in Figure l is loaded into a cartridge case and consolidated.
In Figure l, a cartridge case lO is shown loaded with loose granules of smokeless powder 12. The granules are held -in position in the cartridge case with packing 14.
Figure 2 illustrates an identical cartridge case loaded with an equivalent weight of smokeless powder granules which ~ ~
have been consolidated. To ef~ect consolidation, the surfaces ~ ;
of the granules employed in the cartridge case in Figure 2 are ~;
wet with the vapor of a solvent for nitrocellulose~ and then ;
pressed into the cartridge case with a ram. The packing density - of the propellant granules is thereby increased. Visual com- ,~
parison of the ~ .-'''`'`','~'''','',.

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i space occupied by the smokeless powder granules held within the cartridge cases in Figs. 1 and 2 clearly illustrates the improved packing density, and the volume available for additional smoke-less granules in the cartridge case of Fig. 2, the cased ammuni-tion of this invention.
The consolidated propellant charge employed in the cased ammunition of this invention is preferably prepared as follows.
- A desired amount of smokeless powder granules to be charged to the ~;
cartridge case of the round ammunition are brought to ambient tem- ;
! 10 perature. The smokeless powder granules are then exposed to sol-vent vapor in which the solvent employed is a solvent for the nitrocellulose component of the smokeless powder granules. The exposure time of the smokeless powder granules to the solvent vapor depends on the temperature and concentration of the solvent vapor and the amount of solvation required. The smokeless powder ;
i granules should contain from about 2% to about 8% by weight of solvent after vapor treatment. The solvent vapor can be employed `1 alone or with a diluent gas such as nitrogen. Preferred condi-tions for vapor treatment of the smokeless powder granules util-izing nitrogen gas as a diluent in which the nitrogen is satur-ated with acetone solvent are saturated nitrogen-acetone vapor temperatures of about 80F. and an exposure time of about five - minutes. A particularly suitable solvent which can be employed in vapor form i9 acetone. Other solvents which can be employed include ethyl acetate, butyl acetate, methyl alcohol, methyl .. j ..
~ ethyl ketone, methyl, ethyl, propyl or butyl nitrate, and the ~. . .
~`1 like.

After the surfaces of the smokeless powder granules are :,.
1 wet with solvent-vapor, the ~ranules are loaded into the cart- ~
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;i~ 30 ridge case and are compressed by any suitable means such as by a--ram. Consolidation pressure is from about 500 p.s.i. to about 5000 p.s.i. and will vary depending on the rate of consolidation.
At low rates of consolidation, higher ram pressures are required to produce a self-supporting charge. By the term ~Iself-supporting~

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i5 meant the consolidated charge is unitary or in essence one piece of propellant. The foregoing process o~ wetting smokeless powder granules with solvent vapor, adding the solvent treated granules to the cartridge case and pressing the charge is repeated -until the cartridge case is suitably loaded with consolidated pro-pellant.
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Following the subjecting of the smokeless powder gran-ules to solvent vapor and pressing of the solvent wet smokeless powder granules into the cartridge case, the resulting consoli- ~ `
10 dated charge is heat cured. Suitable curing conditions are curing ~-, temperatures of from about 100F. to about 150F. for times of about 18 hours to about 48 hours. Particularly suitable curing ` conditions are heating of the consolidated charge at a temperature `~
` of about 140F. for about 24 hours.
The following examples more fully illustrate this inven- -~
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` tion. In the examples parts and percentages are by weight unless otherwise specified.
Examples 1 10 .. . . .
, Ten standard 20 millimater M-102 cartridge cases are filled with varying amounts of solvated smokeless powder granules `~
following the vapor treatment process heretofore described in which the solvent employed is acetone. The treated granules-con- -tain about 4% acetone. The solvent treated granules are compressed within said cartridge case to a pressure of about 1000 p~ S o i ~ for aboùt one minute. The weight of smokeless powder granules charged ~ in each case ir as specified in Table I. To achieve the degree i" of loading required, two increments of granules are charged to each case and each increment is pressed separately with the re-` sult that the desired loadin~ is readil~ achieved. ~
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TABLE I

Smokel~ss Powder Chamber Muzzle ~eight Pressure Velocity Ex. ~ (P s.i.) (feet/sec.) 1 700 39,000 3740 2 750 ~8,000 3995 5,000 4128

4 775 49,000 4085 785 55,000 4114 6 785 50,000 40~7 7 785 55,000 4172 8 785 5~,000 4102 9 785 55,500 4135 785 54,000 409 The rounds of Examples 1-10 are fired. Each round is ~
assembled with a penetrator (projectile) having a nominal weight ``
of 1230 grains. Chamber pressure and muzzle velocities measured for these examples are recorded in Table I. For comparison pur-poses a standard 20 millimeter M~102 cartridge case was filled to capacity with a loose charge of smokeless powder of the same composition as that employed in Examples 1-10. The fully loaded case held 630 grains of granules. The round was fired and the ~;-:......... . .
-~ chamber pressure was measured at 50,000 p.s.i. and the muzzle ;' velocity for the charge was 3760 feet per second. It can be seen from review of firing data of rounds 2 through 10, listed in ;~
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Table I, that the muz~le velocity of a round of ammunition pre- ;; ~
:,,, pared employing the cased ammuniti~on of this invention, is about 4000`ft. per second employing a smokeless powder charge weighing ~ ;
from 750-785 grains.
In preparing the cased ammunition of this invention the smokeless powder granules can be pressed up to about 65% of their original-volume. It is preferable, however, only to press the granules to ~rom about 70% to about 75% of the original volume.
-If the granules are compressed to more than about 65% of the original volume, there is likely to be insufficient porosity within the consolidated charge to permit the charge to break up and burn similar to a loose charge o~ smokeless powder granules.

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; Such burning is required in order to obtain uniformity of ballis-tic performance of the consolidated charge.
The term smokeless powder granules is used herein to mean propellant granules of the single base, double base or triple base type. The term cartridge case includes metal, plas~
tic or combustible type cartridge cases. . ~ :

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Claims (6)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a round of cased ammunition comprising a projectile and a metal cartridge case having an internal cavity for holding a propellant charge, and a propellant charge held within said cavity in the metal cartridge case, the improvement comprising a self-supporting, consolidated, porous propellant charge prepared by a process comprising wetting smokeless powder granules with a solvent for the nitrocellulose component of said granules, said solvent being employed as a vapor, said wetting being continued for a time sufficient for said smokeless powder granules to contain from about 2% to about 8% by weight of solvent, consolidating said solvent-wet granules at a pressure of from 500 p.s.i. to 5000 p.s.i. whereby the granules are compacted to form a self-supporting charge, said granules being compacted up to 65% of their original noncompacted volume, and heat curing the resulting consolidated charge.

2. The round of ammunition of claim 1 in which the propellant granules are compressed to 70-75% of their original random, non-compacted volume.

3. The round of ammunition of claim 1 in which the smokeless powder granules are of the single base type.

4. The round of ammunition of claim 1 in which the smokeless powder granules are of the double base type.

5. The round of ammunition of claim 1 in which the propellant granules are of the triple base type.

6. The round of ammunition of claim 1 in which the resulting consoli-dated charge is heat-cured at temperatures of from 100°F to 150°F for 18 to 48 hours.