US3545333A

US3545333A - Methods of manufacturing caseless ammunition for air ignition systems

Info

Publication number: US3545333A
Authority: US
Inventors: Jules Edmond Van Langenhoven
Original assignee: Victor Comptometer Corp
Current assignee: Daisy Manufacturing Co Inc
Priority date: 1961-05-03
Filing date: 1968-07-18
Publication date: 1970-12-08
Anticipated expiration: 1987-12-08
Also published as: US3854400A; DE1796283B2; CH550988A; DE1796283A1; US3530762A; US3561319A; US3521523A; DE1553937A1; DE1728364B1; GB1162952A; US3951038A; US3577921A; CH456398A; US3302523A; GB1162953A; GB1162951A

Description

United States Patent Inventor Appl. No.

Filed Patented Assignee Jules Edmond Van Langenhoven Benton County, Arkansas July 18, 1968 Division of Ser. No. 473,556,

July 7, 1965, which is a continuation-inpart of Ser. No. 189,621, Apr. 23, 1962, abandoned.

Dec. 8, 1970 Victor Comptometer Corporation Chicago, Illinois a corporation of Illinois.

METHODS OF MANUFACTURING CASELESS AMMUNITION FOR AIR IGNITION SYSTEMS 21 Claims, 5 Drawing Figs.

149/18, 96,100:264/3, 3(A). 3(B). 3(C). 3(E) [56] References Cited UNITED STATES PATENTS 702,208 6/1902 102/38 2.230.106 1/1941 264/3(E) 2,261,630 11/1941 264/3(B) 2,381,468 8/1945 149/96 2,771,352 11/1956 149/100 3,163,567 12/1964 264/3(E) FOREIGN PATENTS 1,755 AD/1894 Great Britain 89/7 Primary Examiner-Benjamin A. Borchelt Assistant Examiner-Stephen C. Bentley Att0rneyHarness, Dickey & Pierce ABSTRACT: Caseless ammunition, propellant, and methods of manufacture thereofcomprising a lead projectile to which a relatively large solid one-piece porous homogenous nitrocellulose colloid is attached after mixing nitrocellulose and nitrocellulose solvent and a filler to form a wet doughy mixture of colloided nitrocellulose and filler of particular size and amount providing a predetermined degree of porosity and from which a relatively large one piece body of colloided nitrocellulose and filler is formed into a size and shape corresponding to the size and shape of the caseless ammunition propellant with the tiller being thereafter removed from the formed body.

METHODS OF MANUFACTURING CASELESS AMMUNITION FOR AIR IGNITION SYSTEMS This application is a division of my copending Pat. application Ser. No. 473,556, filed Jul. 7, 1965, which is a continuation-in-part of my prior application Ser. No. 189,621, filed Apr. 23, 1962, now abandoned.

This invention relates to air operated projectile firing apparatus, and more particularly to new and improved means of imparting energy to a projectile for use therewith.

The possibility of using high temperature compressed air to ignite a combustible material, including gun powder, has previously been suggested. Perhaps the best known example of the use of high temperature compressed air for ignition of a combustible material is in internal combustion engines in accordance with the well-known diesel engine principles. Attempts have been made to apply these principles to gun apparatus. For example, in order to increase the projectile velocity in air guns, it has been previously proposed to provide air gun apparatus with a liquid propellant which may be vaporized and ignited during an air compressing stroke of the gun apparatus. In such apparatus, a supply of liquid propellant is connected to the air compression chamber through suitable delivery means which may include a suitable valve mechanism. When the gun is actuated, a propellant charge is delivered by the valve mechanism to the compression chamber. As the piston in the compression chamber is rapidly moved by a spring means, or the like, to reduce the volume of the compression chamber and compress the air therein, the air temperature and pressure rise to a point at which the liquid propellant is vaporized and ignited. The projectile is commonly supported in direct communication with the compression chamber and is driven out of the barrel by the energy released when the liquid propellant is ignited. In apparatus of this type, the air compression chamber and the ignition chamber are one and the same. Consequently, any deleterious products of combustion are deposited in the air compression chamber, on the piston, and on the associated valves. Furthermore, the piston is movable rearwardly in response to increased pressures caused by theignition of the propellant so that a nonrigid reaction wall forms a part of the ignition chamber.

The use of an ignition charge ignitable by compression in a compression chamber and then delivered to a firing chamber to ignite a solid propellant, such as gun powder, associated with a projectile in the gun, hasalso been suggested. In one prior art disclosure, ignition of a charge of high test gasoline by compression of an air gas mixture in a compression chamber directly connected to a projectile chamber has been suggested. It has been further suggested that a propellant associated with the projectile may be ignited by the ignited charge of gasoline.

Although the present invention may appear to have certain similarities to the aforediscussed apparatus, those skilled in the art to which this invention relates will readily appreciate that the distinctive characteristics and the improved results attained by the present invention are substantially different than the prior art.

It is an object of the invention to provide new and improved propellants for use with air ignition apparatus and methods of making such propellants.

A further object is to provide new and improved propellant and projectile combinations.

The foregoing objects, and others, have been attained by the application of the invention principles of the present invention to air ignition system ammunition as hereinafter disclosed by reference to illustrative embodiments of the invention shown on the accompanying drawings wherein:

FIG. 1 is an enlarged sectional view ofone form of ammunition suitable for use with air ignition system apparatus; FIG. 2 is an enlarged side elevational view ofa round of caseless ammunition suitable for use with air ignition apparatus;

FIG. 3 is an enlarged side elevational view of another round of caseless ammunition hot air ignition means of the present invention;

FIG. 4 is an enlarged side elevational view, partly in section, of another form of ammunition; and.

FIG. 5 is an enlarged side elevational view, partly in section, of an alternative form ammunition.

While certain features of the present invention are particularly well adapted for use in air guns, it will be readily appreciated by those skilled in the art to which this invention relates that the inventive principles are also applicable to other devices such as power actuated tools. Also, while certain forms of the ammunition are particularly advantageous in certain applications, the projectile design and the manner of attaching the propellant thereto may be varied as necessary and desirable depending upon such factors as the velocities required, breech pressures attained, the type of gun, and the projectile propellant characteristics.

A round of ammunition 110, FIG. 1, adapted for use with air ignition system apparatus comprises a lead projectile, or the like, having a front end portion 112 and a rear end portion 114. In the illustrative embodiment, the projectile is provided with an inwardly extending bore 116. The rear end portion 114 is slightly outwardly flared as indicated at 118 for abutting obturating. engagement with a similarly contoured portion in a gun barrel. The amount of taper is dependent upon the shot start force desired. With a propellant, the shot start force should be sufficient to hold the projectile in place during the compression stroke until the propellant is ignited. In an air propulsion system, the projectile could be modified to provide a lesser shot start force so that movement would begin at the beginning of the compression stroke. Bore 116 has a corresponding inwardly directed taper 119 as shown. The bore 116 provides a propellant storage and ignition chamber within which one or more propellant caps 120, 121 may be provided. In the embodiment shown, a pair of spaced propellant caps are illustrated. The propellant caps may comprise a nitrocelluloseproduct which is ignitable under the effects of heat and pressure to create high energy. The caps have a disclike form which is readily insertable into the bore 116. The caps have a diameter slightly smaller than the open end of the bore 116 so that they may be pushed along the tapered surface 119 of the bore until they are firmly wedged in the ignition chamber provided thereby.

Although the caps may be me made from any material which is adapted to be decomposed at a high temperature to produce an explosive or gas evolving action Na which may be readily packaged, stored, and handled in a reliable manner, exceptional results are obtained from a porous nitrated cotton product. Nitrocellulose is particularly well suited for this use. A formula for and a method of manufacturing a suitable nitrated cotton product comprises the following steps and procedures; a commercially available cotton may be prepared for nitration by mixing the cotton in a solution of H 0 and Na 2 Cp The mixture is boiled for approximately one hour and the solution level is maintained by the addition of hot water as necessary. A suitable proportion is 50 grams of sterile blenched dry cotton; two liters H 0, and 5 grams Na CO After the cotton has been suitably prepared, it should be rinsed thoroughly. Water at approximately 59 F. may be added to the bottom of the tank in which the cotton has been boiled. Cotton should be held under the water during rinsing and the rinsing operation should continue until pH of 7 is attained. If necessary, a second rinse may be utilized to insure that the cotton is thoroughly cleaned. Then the cotton should be subjected to a centrifuging action or the like, to remove most of the water. Then the cotton should be dried, for example, in an oven at approximately F.

After the cotton has been suitably prepared, it is nitrated by mixing in a solution of nitric acid, sulfuric acid, and potassium nitrate. The nitric acid is first added. to the sulfuric acid and mixed at approximately 41 F. and care should be taken to keep the temperature below approximately 59 F. while mixing. Then the potassium nitrate is added and density, temperature is maintained below 50 F. A suitable formula is 148 grams of nitric acid, 1.48 density, 452 grams sulfuric acid, 1 .842 density, and 69 grams potassium nitrate.

After the nitration solution has been prepared, the dry cotton is added to and mixed in the solution. Again the solution 70should be maintained at approximately 59 F. and 77cotton temperature should beat about 68--77 F. In a nitration formula as described above, approximately 22.3 grams of the dry cotton is added to the 669 grams of the nitrating solution. The cotton should be soaked in the nitrating solution for approximately lO hours with the temperature being maintained below approximately 77 F. After the cotton has been soaked in the nitrating solution, the cotton is removed from the solution and rinsed in pure water until a pH of 7 is again obtained. Then the nitrated cotton may be subjected to the action of a centrifuge and dried at 77 Fund] a moisture content of approximately 7 percent is obtained.

With the aforedescribed nitrated cotton product, the caps are very porous, easily ignited, completely burned upon ignition, and no undesirable residues are left in the barrel or the associated parts of the gun. While in most instances, the propellant may be manufactured, stored, and used in a solid stable form, it may be desirable, in some instances cases, to cover the propellant discs with a thin plastic like film over the entire periphery. The plastic like film may take various forms and, for example, be provided by the nitrating solution itself.

Another aspect of the invention relates to hot air ignition of a propellant associated with a projectile. The temperature attained by the compressed air in an air gun, which is directly related to the pressure attained and heat loss sustained, is sufficient to ignite a charge suitably associated with a projectile in the gun. In one form, the charge may be fitted inside a charge cavity provided at the rear of the projectile and in another form, the charge may be mounted on the rear of the projectile. The charge preferably takes the form of one or more caps formed from a substance which is adapted to decompose or burn-under the combined effect of temperature and pressure. The temperature and pressure of air in the compression chamber is sufiicient to decompose and burn the material. Particularly advantageous results may be obtained by the use of a porous nitrocellulose material or a similar explosive manufactured in pellet or cap form is hereinbefore described.

It is possible with the apparatus of the present invention to utilize an ignitable propellant by which a level of energy sufficient for relatively high velocity propulsion may be obtained. The propellant may be associated with and carried by the projectile prior to loading of the gun. As previously described, solid nitrocellulose caps 120, 121 may be mounted in a cavity 110 provided in the end of the projectile. The caps are ignitable when subjected to high temperatures, and when ignited provide a high energy source for projectile propulsion. In general, while certain propellants might be ignitable at lower temperatures, it is desirable to provide compression means by which temperatures in the range of 400 F. to 700 F. are attainable.

Caseless rounds of ammunition,indicated generally by the reference numeral 301, are shown in detail in FIGS. 2 and 3. In the presently preferred form of the invention, each round 301 comprises a metallic (e.g. lead) slug having a generally cylindrical section 302, complementary in diameter to the gun bore, and an end section 303. A beveled section 304, connecting

sections

302 and 303, is adapted to abuttingly engage a beveled section of a projectile cavity in the firearm. The diameter of the cylindrical portion 302 is sufficiently larger than the diameter of the firearm bore so as to form a seal and to hold the projectile in place in the ammunition chamber until the propellant has been ignited and sufficient force is obtained to compress the lead projectile and force it into and down the firearm bore.

Propellant attaching means are provided in the form of a stub shaft portion 305, integrally connected to the cylindrical section 302, and terminating in a radially displaced upset portion 306. In the presently preferred embodiment of the invention, a disc of solid propellant 307, a corresponding in diameter to a cylindrical section 302, is fixed to the stub shaft portion and held in place by upset v portion 306. While the presently preferred manner of associating the propellant with the projectile provides particularly advantageous results, it is contemplated that the propellant might be otherwise attached such as by directly bonding the propellant the rear of the projectile without utilizing the post 305. In the preferred embodiment, the length of the propellant portion is approximately equal to the length of the main portions of the projectile. The propellant 307 may be of any type, which is sufficiently porous to be ignitable by surface contact with high temperature air such as compressed within the firing chamber 296 by the air compression unit 225, as will become more apparent as this discription proceeds. The propellant 307 may be made pro jectile. The layers may have successively higher ignition points progressing toward the projectile to provide a neater thrust if so desired or may be otherwise varied and modified to attain particular ignition and firing characteristics.

In the presently preferred form of the invention, the propellant is manufactured into a doughy mass suitable for formation in pellet or cap form separately from the projectile or directly on the projectile. This type of ammunition is caseless and the entire round is fired from the gun without residue.

The propellant made in accordance with the practice of the present invention is formed into porous pellets containing as essential elements therein an ignitable explosive material and a cellulose binder material.

The explosive constituent may consist of any of the wellknown single-base, double-base, or triple-base explosive materials consisting principally of commercially available nitrocellulose having a degree of nitration usually from about 13.2 percent to 13.5 percent N and which is also known as guncotton or smokeless powder. The nitrocellulose explosive constituent can be employed in any of the commercially available forms such as, for example, in the form of fibers (E.G. water system) or solvent-softened grains e.g. solvent system), to provide the desired burning characteristics and porosity of the resultant propellant pellet. In forming nitrocellulose grains, any one of a variety of suitable solvents can be satisfactorily employed which are miscible or emulsifiable with water in order to assure uniform distribution thereof and wetting of the nitrocellulose fibers. Solvents which are particularly suitable for this purpose include acetone, methyl ethyl ketone, dimethyl ether, diethylene glycol, ethyl glycol, or the like, of which acetone is the preferred solvent. The solvent can be employed either individually or in mixtures thereof in order to achieve the desired swelling of the nitrocellulose explosive constituent. So called double-base explosives can also be satisfactorily employed for the purposes of the present invention by adding nitroglycerins to the nitrocellulose in amounts conventionally ranging from about 5 percent up to about 40 Similarly, triple-base explosives can can be made by additionally adding nitroguanidine to the nitrocellulose containing the nitroglycerine.

In addition to the explosive constituent, the mixture employed for forming the propellant also includes a water-soluble or water-solvent soluble organic binding agent which is effective to retain the water or water-solvent employed during formation of a pasty or doughlike mixture and during the shaping, casting, or extrusion thereof into wet slugs or pellets of the desired shape and size. Subsequently, the a water or water-solvent is removed to provide the desired porosity. Binding agents which have been found particularly suitable for this purpose include cellulose derivatives such as methylcellulose, hydroxyethy] cellulose, carboxymethyl cellulose, carboxyethyl cellulose, starch, arabic gum, or the like. The quantity of the cellulose binder material employed is dependent on the quantity of water used in the mixture and is controlled in an amount to prevent excessive exudation of the water during the forming or shaping of the wet mixture into slugs. In most instances, the cellulose binder material is employed in amounts ranging from about 3 percent up to about 20 percent by weight based on the nitrocellulose constituent present, and quantities of about 10 percent by weight are preferred. On the other hand, the use of the cellulose binder in amounts greater than about 20 percent by weight has been found to effect an excessive dilution of the explosive charge, preventing the attainment of the desired burning rate and pressure of the explosive when ignited. It is for this reason that the cellulose binder material is usually employed in amounts ranging from about 3 percent up to about 20 percent by weight.

In addition to the foregoing constituents, any one or combinations of accelerators or retardants, as well as stabilizing agents of the types well known in the art, can be satisfactorily included to provide the requisite ignition, and rate-of-burn characteristics to the resultant propellant as well as to enhance its stability during prolonged periods of storage. Typical accelerating agents include water-free nitrates, while a typical stabilizing agent is represented by diphenylamine.

The mixture of the explosive constituent and binder constituent, which may additionally include the accelerating agents, stabilizing agent, or 40 retardants as desired, is blended with water or water and solvent in an amount sufficient to form a pastelike or doughy mass which can conveniently be molded, case, or extruded into wet pellets of the desired configuration and size. The quantity of water employed is not critical and can be varied consistent with the shaping operation employed to achieve optimum forming characteristics. The amount of water or water and solvent employed in the mass does affect the resultant porosity of the propellant formed, since, upon evaporation of the water or water and solvent from the shaped pellet, voids are formed to a greater or lesser extent which affect the rate of burning of the propellant. The formation of a uniform wet mixture of the several constituents can be conveniently achieved in any one of a variety of mixing apparatus which preferably are provided with means for preventing or inhibiting the evaporation of water from the mass during mixing. After a substantially uniform wet mass is obtained of the desired consistency, the mass can be readily formed, preferably by extrusion, into a plurality of pellets of the desired cross-sectional configuration and of length consistent with its intended end use. The wet pellets are subsequently dried to effect a vaporization of substantially all of the water contained therein, in addition to any solvent introduced for the purpose of gelatinizing the nitrocellulose fibers employed, providing therewith a dry porous matrix consisting of the nitrocellulose fibers or granules securely bonded by the cellulose binder. The resulting propellant can bev repeatedly handled, exposed to varying humidity and normal temperature conditions, and stored for long periods of time without deterioration resulting in loss of explosive power and velocity during firing.

The conditions of manufacture and use may require additional agents for special purposes. For example, the use of a stabilizer, such a as diphenylamine, is generally advantageous and the use of a dye, with the exception of amine or acid dyes, for coloring the final product may be employed. A suitable oxidizing agent may be employed to provide better burning characteristics and suitable breech pressure reducing agents may be advantageously employed.

One type of propellant suitable for use with the apparatus of the present invention is manufactured by use of water to obtain the desired degree of porosity and is sometimes referred toas a Water System" propellant.

An exemplary formulation of such a Water System" propellant comprises:

200 grams-Nitreellulose (13.35% N;,, 30% water by weight).

1 gram-Diphenylamine.

5 grarns-Hydroxyethyl cellulose (dry).

gramsPotassium nitrate.

5 cc.Castor oil.

grams-Alurninum stearate.

110 cc.-Acetone.

50 cc.-Wa.ter.

The nitrocellulose is a commercial grade (N 13.35 percent l3/45 percent) available from Hercules Powder Company. it

is made from cotton linters with a fineness of to M]. and a viscosity of 8 to 20 seconds. It has an ether-alcohol solubility of ll percent and is manufactured in accordance with MIL-N-244. The diphenylamine is utilized as a stabilizer as is conventional. The hydroxyethyl cellulose is sold under the trade name of Natrosol by Hercules Powder Company and has a high viscosity (eg 4000 centipoises). It provides a water soluble binder, Other types of water soluble binders might be used such as methyl cellulose, cellulose monochloracetate, ethyl hydroxeythyl cellulose. The potassium nitrate is utilized as an accelerator due to its ability to liberate oxygen during burning of the propellant. Castor oil is utilized for lubricating purposes both in the manufacture of the propellant during extrusion and in use in the gun. The aluminum stearate acts as an inhibitor or retardant to reduce the rate of burning and breech pressures. The acetone is a solvent for the water soluble binder and acts with the water for to form a filler, which is subsequently removed to obtain the desired porosity, and to dissolve and disperse the binder through out the nitrocellulose, the fiber structure of the nitrocellulose remaining substantially unchanged.

The method of mixing and preparing the foregoing formulation comprises initially establishing the water content of the wet nitrocellulose and adjusting the water content as necessary to obtain 30 percent water by weight so that the 200 grams of nitrocellulose will contain grams of dry nitrocellulose and 60 grams of water. Then 200 grams of the wet nitrocellulose (water wet 30 percent by weight) is added to 5 grams of the hydroxyethyl cellulose (dry). The nitrocellulose and hydroxyethyl cellulose are mixed by tumbling in a closed container for approximately 10 minutes at ll40 F. It is desirable to keep the mix in the container for an additional time (i.e. approximately 20 minutes) until the water soluble binder has begun to swell. Then the mix may be cooled to room temperature whereupon the potassium nitrate and the aluminum stearate are added to the mixture. Then the diphenylamine and the castor oil are dissolved in the acetone and added to the mixture. It is then desirable to tumble the mixture in a closed container for about 5 minutes and then transfer the tumbled mixture to a closed mixer for mixing approximately 30 minutes. At this time, it is desirable to add 50 cc of water an mix for another 30 minutes.

As a result of the foregoing, the water soluble binder is dispersed throughout the nitrocellulose fibers in a pasty doughy mass and is ready to be molded onto the projectiles. The projectile, of the type shown in FIGS. 2 and 3, is supported with a suitable die enclosing the stub shaft portion and forming a die cavity there around approximately equal to the diameter of the projectile with suitable allowance for shrinkage ad and the like. The doughy mass is extruded into the die cavity around the stub shaft portion. The propellant dough is confined so that it a cannot flow past the projectile and enough propellant dough is injected to fill the die cavity and produce the desired length and diameter pellet when dry. The water and acetone are then remove-d by evaporation to produce voids between the cotton fibers resulting in the desired degree of porosity. A quantity of this propellant equal to 85 mg will propel a .22 caliber projectile of 29 grain weight with a muzzle velocity of approximately 1,200 feet per second.

If it is desired to produce a lower velocity propellant, the following formulation may be used:

200 gramsNitroeellulose (13.35% N 30% water by weight).

5 grams-Hydroxyethyl cellulose.

10 grams-Potassium nitrate.

1 gram-Diphenylamine.

ee.Acetone.

85 ec.-Water.

By mixing this formulation as hereinbefore described, a propellant producing a muzzle velocity of approximately L100 feet per second with a 29 grain bullet will be obtained.

This 1,100 feet per second formulation may be used in combination with the 1,200 feet per second formulation as an ignition charge as shown in FIG. 2. The main charge 307a is extruded onto the projectile first as hereinbefore described. 1mmediately thereafter, the projectile and main charge are displaced slightly in the die means and the ignition charge 307b may be extruded into the rear of the main charge. In the presently preferred form, shown in FIG. 2, the ignition charge is centrally placed in the rear of the main charge in a somewhat semispherical form surrounded with and embedded in the main charge except for an exposed rear surface.

In order to vary the velocity, it may be desirable to change the amount of propellant of any given formulation attached to the projectile. However, it is necessary and desirable to have the dimensions of the ammunition remain constant. An inert change may be first extruded onto the projectile to occupy a portion of the volume of the normal propellant cavity. An exemplary formulation for the inert charge comprises:

A technical grade of talcum powder such as that sold by Fisher Scientific Company has been found to be satisfactory. This mixture should be kneaded into a doughy mass for approximately 30 minutes at room temperature before being extruded. It is important that the inert dough have sufficient consistency to set up on the projectile without tending to flow past the projectile. In one illustrative arrangement, shown in FIG. 3, producing a velocity of approximately 700 feet per second with the 1,100 feet per second propellant initially described, a volume of the inert charge 3070 equal to the projectile diameter by 130 long is molded onto the rear of the projectile. Then a quantity of the 1,100 feet per second propellant 307d equal to the projectile diameter by .090 long is molded onto the rear of the inert charge. This amount of the propellant will produce a velocity of approximately 700 feet per second.

Another type of propellant suitable for use with the apparatus of the present invention is manufactured by use of a salt to obtain the desired degree of porosity and is sometimes referred to as a Salt System propellant.

Exemplary formulations of such a Salt System propellant comprises:

A. 100 gramsNitroeellulose (13.3445% N dry).

200 grams-Potassium nitrate (through #100 sieve on #120 sieve). 1 gram-Diphenylamine. 100 cc.Acetone. 100 gramsNitrocellulose (13.35.45% N dry).

300 gramsPotassium nitrate (through #100 sieve on #120 sieve). 1 gram-Diphenylamine. 225 cc.-A. cetone. 100 gramsNitrocel1ulose (13.35.45% N dry).

400 gramsPotassium nitrate (through #100 sieve on #120 sieve). 1 gramDiphenylamine. 300 cc.Acetone.

The nitrocellulose is a commercially available grade (N 13.35percent 13.45 percent) sold by Hercules Powder Company as hereinbefore described. The potassium nitrate is used as a filler which is subsequently removed to produce the desired porosity in the propellant. The diphenylamine is a stabilizer, as is conventional, and the acetone is a solvent which destroys the fig fiber structure of the nitrocellulose and forms a doughy mass.

The method of mixing and preparing the foregoing propellant formulations compresses preblending of the diphenylamine and the acetone and then mixing of the entire formulation in a closed container for about on one hour. The consistency of the propellant may be improved by extruding the mass several times. lt is important to maintain uniform extrusion speed. After the final extrusion, which may be the fifth extrusion, the extruded material may be hung to dry at room temperature for approximately 15 hours to minimize dimensional distortion. The propellant material may be extruded in a tubular form. For a propellant of type A, a inch .250 inch nozzle and a .062 inch pin are utilized so that, after washing and drying, the outside diameter of the propellant will be about .220 inches and the inside diameter will be about .045 inches. When the material has been dried, it is cut to lengths of about .169 inches with a .010 wide slotting saw. A propellant pellet of approximately 157 mg is thus provided which, after washing, will weight about 50 mg. After cutting, the potassium nitrate is removed from the pellets by washing the pellets for approximately four days in slowly running water at about 140 F. Thereafter, the propellant pellets are dried for approximately 24 hours and then the still wet propellant may be pressed onto the post at the rear of the projectile. The 157 mg (50 after washing) pellet of propellant will produce velocities of approximately 1,100 feet per second on a projectile weighing 1.93 grams. It is to be understood that the propellant also may be extruded onto the projectile or molded thereon.

Still another type of propellant suitable for use with the apparatus of the present invention is manufactured by use of a solvent in place of the water-acetone in the water system to obtain the desired degree of porosity and is sometimes referred to as a Solvent System." An exemplary formulation of such a Solvent System propellant comprises:

gramsNitrocellulose (13.35%.45 dry).

1 gram-Diphenylamine.

cc.Toluene.

20 cc.-Alcohol (denatured or isopropylalcohol). 25 cc.-Acetone.

5 gramsAluminum stearate.

5 grams-Ethyl cellulose (high viscosity, K 5000). 1.87 gramsPotassium nitrate.

The nitrocellulose is a commercially available grade as hereinbefore described. The diphenylamine acts as a stabilizer and the aluminum sterate acts as a retardant to reduce breech pressures. The toluene is a liquid filler by which the desired degree of porosity is attained. Other suitable liquid fillers include toluene and xylene. The alcohol is utilized to prevent the toluene from reacting with the nitrocellulose. The acetone is utilized to partially react with the nitrocellulose causing the nitrocellulose to swell and expand without destroying the fiber structure. The ethyl cellulose acts as a binder for the liquids so as to produce a doughy mass. The potassium nitrate acts as an accelerator producing oxygen during burning.

The method of preparing the propellant comprises mixing the toluene, alcohol, and acetone, and then adding the ethyl.

cellulose and the diphenylamine. This mixture is then thoroughly mixed for approximately two hours at room temperature so that the ethyl cellulose is entirely dispersed in the solvents. Then the dry nitrocellulose and all aluminum stearate are added and mixed for approximately one hour. At this time, the propellant is in the form of a doughy mass ready for molding into a tubular form for subsequent association with the projectile or for direct molding onto the projectile as hereinbefore described. After the molded pellets have been at room temperature for about 5 minutes, they are boiled in a 2V2percent potassium nitrate water solution for approximately 15 minutes and are then dried at F. Boiling of the pellets in the KNO water solution reduces shrinkage and increases the rate of removal of the solvents to produce the voids in the propellant. Consequently, no further rinsing is required and the remaining KNO will act as an oxidizing agent during burning of the propellant.

Advantages of these propellants are that they may be economically manufactured, they are stable both in manufacture and use under normal conditions, they may be easily associated with a projectile to form caseless type ammunition,

and they will burn cleanly and minimize corrosion of the gun parts. Furthermore, while being stable and harmless in association with a projectile during manufacture, storage, and handling, when properly positioned in a firing chamber of a gun, they are capable of being ignited and generating high energy gases, which when properly confined, are capable of propelling a projectile through a gun barrel at high velocity. While the propellant attached to the projectile can be ignited in the open by a flame from a match or the like, the propellant merely burns at a slow rate causing no movement of the pro jectile and is completely harmless. In addition, the propellants and the methods of making them provide versatility and flexibility to enable propellants of varying degrees of porosity to be obtained in a manner which is simpler and more economical than previously known.

Referring to FIG. 4, ammunition 730 to be driven from a powder actuated stud driving comprises a projectile portion in the form of a stud having an elongated shank portion 732, terminating in a pointed end 733, and a headed portion 734. A propellant portion of the round of the ammunition comprises, in the illustrative embodiment, plug means 738 attached to the projectile head portion and providing support means 738, obturation means 740, and propellant attaching means 742. The plug means may be made of any suitable material, such as plastic materials, which will be capable of being compressed and driven through the barrel after ignition of the propellant. 1n the illustrative embodiment, the propellant 744 is mounted in a cavity at the rear of the plug with a surface exposed for surface contact with high temperature air delivered through passage 706. It will be understood that the propellant may be otherwise attached or associated with the projectile. Referring now to FIG. 5 an alternative projectile form is shown to comprise a threaded head portion 748 with the plug means 736 being generally cylindrical and molded or extruded onto the threaded head portion as shown.

In the broadest aspects of the present invention is it contemplated that other types of propellant may be used and that other propellant ignition means may also be provided. However, particularly advantageous results are obtained by the use of the particular propellant and the particular means of igni tion the propellant disclosed. Obviously, the details of construction and the arrangement of the parts may be varied without departing from the principles herein disclosed. Since the inventive principles disclosed herein have obvious application in alternative combinations, it is intended that the scope of this invention as defined by the appended claims include those alternative embodiments which utilize the inventive principles herein disclosed.

lclaim:

l. The method of manufacture of caseless ammunition for a firearm comprising a projectile portion and a relatively large solid one piece porous ungranulated propellant portion ignitable by surface contact with high temperature air comprising the steps of:

l, forming a wet uniformly mixed doughy gelantinized mass of a composition of nitrocellulose, a nitrocellulose solvent, and a removable filler;

2. forming a relatively large one piece ungranulated propellant body of nitrocellulose and removable filler from the wet uniformly mixed doughy gelantinized mass, the body being of predetermined size and shape equal to or greater in size than the propellant portion;

3. removing the filler from the ungranulated propellant body to form voids in the nitrocellulose;

4. hardening and drying the propellant body in ungranulated form while retaining the voids to provide a desired degree of porosity; and

5. mounting the propellant body in association with the projectile without granulation.

2. The invention as defined in claim 1 and the propellant body being mounted on the projectile portion prior to hardening and drying.

3. The invention as defined in claim 1 and the propellant body being larger than the propellant portion, and the propellant portion being severed from the propellant body and then mounted on the projectile portion.

4. The method as defined in claim 1 and the composition being formed approximately in the ratio of 1 part by weight nitrocellulose and 2-4 parts by weight of removable tiller.

5. The method as defined in claim 1 and the composition being formed approximately in the ratio of l part by weight nitrocellulose and 2 parts by weight removable filler.

6. The method as defined in claim 1 and the composition being formed approximately in the ratio of 1 part by weight nitrocellulose and 3 parts by weight removable filler.

7. The method as defined in claim 1 and the composition being formed approximately in the ratio of l by weight nitrocellulose and 4 parts by weight removable filler.

8. The method as defined in claim 1 and the removable filler being a solid particulate material.

9, The method as defined in claim 3 and the solid particulate removable filler being of predetermined size.

10. The method as defined in claim 9 and the solid particle filler comprising particles approximately of a size such as to pass through a sieve sieve and be retained on a 0120 sieve.

11. The method as defined in claim 1 and the removable filler being a liquid.

12. The method as defined in claim 11 and the composition further including a cellulose binder.

13. The method as defined in claim 1 and the removable filler being toluene.

14. The method as defined in claim 13 and the cellulose solvent being acetone.

15. The method ad as defined in claim 14 and the composition further comprising alcohol.

16. The method ad defined in claim 15 and wherein the toluene, alcohol, and acetone are separately mixed, then a cellulose binder is added and mixed, and then the nitrocellulose is added and mixed.

17. A process for manufacturing a. relatively large ungranulated solid porous firearm propellant body which comprises the steps of: forming a wet uniform doughy mass consisting of nitrocellulose, a cellulose solvent, and a removable filler, forming the wet doughy mass into a relatively large body of ungranulated propellant of a size and shape suitable for as sociation with a projectile as formed to provide the propellant charge therefor, and removing at least portions of the filler from the body of ungranulated propellant to form voids and obtain a desired degree of porosity.

18. The method of manufacturing of a porous relatively large one piece solid propellant of a size and shape by itself forming the charge for a firearm comprising the steps of: wet mixing of nitrocellulose and a soluble nitrocellulose binder and a cellulose solvent and a removable filler to form a wet pasty doughy mass, wet formation of a propellant body of the approximate size and shape of said relatively large one piece propellant having the removable filler dispersed therein, solidification of the cellulose in the propellant body form, and removal of the filler to form voids throughout.

19. The method of producing a relatively large solid porous propellant body of a size and shape by itself forming the charge for firearm ammunition comprising the steps of: Forming a mixture comprising toluene, alcohol, acetone, and nitrocellulose into a wet doughy mass; forming the wet doughy mass into a shaped form at least as large as the propellant body; boiling the shaped form in water to remove the toluene and alcohol and acetone and form voids; and then drying the shaped form to form a solid porous nitrocellulose propellant body suitable for association with a projectile to form ammunition for a firearm.

20. The method of manufacture of caseless ammunition for a firearm comprising a projectile portion and a propellant portion ignitable by surface contact with high temperature air comprising the steps of:

1. forming a wet uniformly mixed doughy mass of a composition of nitrocellulose, a nitrocellulose solvent, and a removable filler;

2. forming a propellant body of predetermined size and shape equal to or greater in size than the propellant portion from the wet uniformly mixed doughy mass;

3. removing the filler to form voids in the nitrocellulose;

4. mounting the propellant body on the projectile portion;

5. hardening and drying the propellant body while retaining the voids to provide a desired degree of porosity.

21. The process of manufacturing caseless ammunition for an air ignition system firearm, said caseless ammunition comprising a projectile portion and a propellant portion, said process comprising the steps of:

1. manufacturing a large hard porous body of ungranulated colloided nitrocellulose by a. mixing nitrocellulose an and a nitrocellulose solvent and a removable fillerto form a wet extrudable doughy mass of gelatinized nitrocellulose having the removable filler uniformly dispersed throughout,

b. forming a large body of ungranulated nitrocellulose from the wet extrudable doughy mass and of a size and shape generally corresponding to the size and shape of the propellant portion of the'ammunition and with the removable filler uniformly dispersed throughout,

0. removing the filler from the large body of ungranulated nitrocellulose to provide a large porous body of nitrocellulose,

d. drying and hardening the large porous body of ungranulated nitrocellulose to provide a large hard porous body of ungranulated colloided nitrocellulose; and

2. permanently attaching the large'hard porous body of ungranulated colloided nitrocellulose to the projectile without further change in the composition or general size of the body with at least one surface of said body being orgy/cred and exposed for direct: Contact with hot ignition air. v a

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 545, 333 Dated December 8, 1970 flx) Jules E. Van Langenhoven It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, lines 74-75, delete "hot air ignition means of the present invention". Column 2, lines 52-53, "Na Cp should be --Na CO line 72, delete "density," and insert therefor --the--. Column 3, line 3, delete "70" and insert therefor --temperature, delete "77 and insert therefor --the-; line 20, delete "instances"; line 4'7, '11! should be -116-; line 722, delete "a" (second occurrence). Column line 3, after "propellant" insert --to--; line 11, after "be" insert --of any type, which is sufficiently porous to be ignitable by surface contact with high temperature air such as compressed within the firi1 chamber 296 by the air compression unit 225, as will become more apparent as this description proceeds. The propellant 307 may be made up of a homogeneous mass of propellant material of several 1a; of different propellant material each of which may be molded, extrud or otherwise mounted on the--, delete "made"; line 13, delete "neat( and insert therefor -greater--; line 34, "E. G. should be --e. g. before 'e. g. (second occurrence) insert a parenthesis line after "40" insert delete "can" (second occurrence); line 59, delete "a". Column 5, line 16, delete "40"; line 19, "case" should b --cast--; line 50, after "such" delete "a". Column 6, line 17, delet "for"; line 42, "an" should be --and-; line 50, delete 'ad"; line 52, delete "a". Column 7, line 47, "45%" should be --.45%-; line 51, "10000" should be -160cc--; line 69, delete "fig". Column 8, line I delete "inch" (first occurrence); line 46, delete "toluene" and insert therefor -benzene-; line 58, delete "all". Column 9, line 17, afte "driving" insert --tool--; line 37, "is it" should be --it is--. Colun 10, line 15, after "1 insert --part--; line 21, "particle" should be --particulate--, line 23, delete 'sieve" (first occurrence), insert before "100", change "0120" to --#120-; line 33, delete "ad"; line E ORM PC3-1050 (10-59) -gc at s us novllmunn nnmno orncz; nu

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PAG] Patent No. 3, 333 Dated December 8, 1970 InventoflX) Jules E. Van Langenhoven It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

"ad" should be --as-. Column 11, line 17, delete "an". In the References: "2, 230, 106' should be -2, 230, l00-.

Signed and sealed this 11th day of May 1971.

(SEAL) Attest:

WILLIAM E. SCHUYLER EDWARD M.FLETCHER,JR. Attesting Officer Commissioner of Pat USCOMM-DC E CIFWI PO-IOSO (\O-691 a u.s. sovnmmn "mums omcs; no