US3482516A

US3482516A - Caseless cartridges having the projectile housed in the propellant charge

Info

Publication number: US3482516A
Application number: US694310A
Authority: US
Inventors: Leonard J Farmer; John A Ruth
Original assignee: Hercules LLC
Current assignee: Hercules LLC
Priority date: 1967-12-28
Filing date: 1967-12-28
Publication date: 1969-12-09
Anticipated expiration: 1986-12-09

Description

Dec. 9, 1-969 FARMER ET AL 3,482,516

CASELESS- CARTRIDGES HAVING THE PROJECTIL'E HOUSED IN THE PROPELLANT CHARGE Filed Dec. 28. 1967 FIG. I

LEONARD J. FARMER F l G. 4 INVENTORS.

ATTORNEY United States Patent CASELESS CARTRIDGES HAVING THE PROJEC- TILE HQUSED IN T HE PROPELLANT CHARGE Leonard J. Farmer and John A. Ruth, Wilmington, Del.,

assignors to Hercules Incorporated, Wilmington, Del.,

a corporation of Delaware Filed Dec. 28, 1967, Ser. No. 694,310 Int. Cl. F42b /18 US. Cl. 102-38 8 Claims ABSTRACT OF THE DISCLOSURE A round of caseless ammunition is provided wherein the projectile is completely housed within an axial bore in a propellant charge. The primer is secured within the propellant charge in axial alignment with the projectile.

This invention relates to a round of caseless ammunition in which the projectile is completely housed in propellant.

Firearm designers have long recognized the advantages of caseless ammunition. Caseless ammunition is light in weight and it eliminates the need for extraction and ejection of spent cartridge cases, making higher firing rates possible. The problem of disposing of spent cartridge cases is also eliminated. The caseless ammunition of this invention incorporates the desirable characteristics of caseless ammunition heretofore described while providing rounds which are very compact and having unique outside configurations.

Broadly, in accordance with this invention, there is provided a round of caseless ammunition having in combination a projectile, a primer, and a propellant charge having an axial bore. The projectile is housed within the axial bore of the propellant charge. The wall of propellant; formed by the axial bore in the propellant charge, surrounds the projectile. A round of caseless ammunition in which the projectile is housed in propellant as described is referred to hereinafter as a telescoped round. In the telescoped rounds of this invention the entire length of the projectile is surrounded by propellant.

The telescoped round of ammunition of this invention offers many advantages to firearm designers over both the conventional and caseless ammunition known in the prior art. The telescoped round can have varied outside configurations such as that of a cylinder or a parallelepiped. New and simple chamber designs for single shot and automatic weapons are therefore possible. The telescoped rounds can be made more compact than conventional caseless rounds and yet have substantially the same ballistic performance as conventional caseless rounds. The compactness of the telescoped rounds makes them easy to handle and eliminates potential operational difiiculties in the gun mechanism.

Various advantages of the invention will become more fully apparent from the following description of the drawings, illustrating representative embodiments of this invention.

FIG. 1 is a vertical section of a longitudinal view of a telescoped round of caseless ammunition.

FIG. 2 is a vertical section of a longitudinal View of another embodiment of a telescoped round of caseless ammunition.

. FIG. 3 is a vertical section of a longitudinal view of still another embodiment of a telescoped round of caseless ammunition.

FIG. 4 is a vertical section of a longitudinal view of a bolt operated firearm loaded with a telescoped round of caseless ammunition.

In FIG. 1 a projectile is housed within the bore 12 of a propellant charge 14. The projectile 10' is secured at the base 16 of the bore of the propellant charge. The propellant charge 14 has an axial recess 17 into which a primer 18 is secured. The propellant charge 14 is ignited by initiation of the primer 18.

FIG. 2 illustrates a slightly dilferent embodiment of a telescoped round of caseless ammunition. In FIG. 2 the projectile 20 is centered and secured at the fore end 22 of the bore of the propellant charge 24 by a cap 26. The projectile 20 is held in place at the aft end by a plug 28 which contains an axial cavity 30. The primer 32 is secured into the aft end of the cavity in the plug. An auxiliary ignition charge 34 is held in the forward end of the axial cavity in the plug between the aft end of the projectile 20 and the primer 32. Both the cap 26 and the plug 28 are adhesively secured to the wall of molded propellant 36 formed by the axial bore through the propellant charge.

FIG. 3 illustrates a telescoped round of caseless ammunition wherein a subcaliber projectile 38 is secured within the axial bore 40 of the propellant charge 42 by a sabot 44 and sabot base 46. The round is secured at the forward end by a combustible cap 50. The sabot 44 and sabot base 46 can be prepared from a light weight metal such as aluminum. The sabot 44 can have one or more driving bands 52 to impart spin to the projectile. The sabot 44 and sabot base 46 leave the chamber of the firearm, in which the telescoped round is fired, with the projectile 38. The sabot 44 and sabot base 46 are prepared in segments so that they readily separate from the projectile in flight. The sabot 44 and sabot base 46, as described, are often referred to simply as the sabot. The sabot is a thrust transmitting carrier for the projectile. A combustible plug 54 containing a primer 56 and an auxiliary ignition charge 58 is adhesively secured in the aft end of the bore 40 of the propellant charge 42, and holds the sabot base 46 in position.

FIG. 4 illustrates positioning of a telescoped round 60 in the chamber of a firearm. In FIG. 4 the telescoped round is loaded into the forward end of the chamber 62 of the firearm. An obturated firing pin 64 housed in an obturated bolt 66 is used to initiate the primer 68.

As illustrated in FIGS. 1-4, the propellant charge of this invention contains an axial bore of a length equal to or greater than the length of the projectile to be used. The diameter of the bore is substantially equal to or greater than the maximum outside diameter of the projectile so that the projectile can be housed within the bore of the propellant charge. The primer is positioned behind the base of the projectile when the projectile is seated within the bore of the propellant charge. The primer is in axial alignment with the projectile.

The projectile and the primer can be secured within the propellant charge by any suitable method. The projectile, for example, can be secured with adhesives alone, or it can be secured by use of a nose cap and adhesive in the fore end of the round and by a plug and adhesive in the aft end. The nose cap and plug are of a slightly smaller diameter than the diameter of the bore and fit into the bore of the propellant charge. The nose cap can be made of a readily combustible material such as Styrofoam. The plug can be made of a readily combustible material such as Styrofoam or it can be made from propellant. The primer can be secured within a recess inthe propellant charge as illustrated in FIG. 1 or it can be secured inside a cavity in the plug used to support the projectile as shown in FIG. 2. It is readily apparent that many variations in securing the projectile and the primer within the propellant charge are feasible. The materials used for this purpose must be compatible with the propellant formulation constituting the propellant charge.

The propellant which can be used to prepare the propellant charge can be of the single base, double base, triple base, or composite type propellant compositions. The propellant is uitilized in the form of small granules. The propellant charge is generally prepared by moulding of the propellant to the desired configuration. For example, if a single or double base composition is chosen for the propellant, it is generally preferred to prepare the charge by filling a mold with small granules of propellant such as smokeless powder granules and adding a binder such as a mixture of collodi-an and acetone. The mold is then pressurized at from about 500 p.s.i.-2000 p.s.i. from fractions of a second to about a minute. A propellant charge is recovered from the mold and dried.

The primers which can be empolyed with the telescoped rounds are of the combustible type and can be prepared, for example, from molded propellant filled with a standard priming mixture, and secured to the telescoped round as desired. The primers can also consist simply of an axial cavity in the base of the propellant charge or combustible plug, said cavity being filled with a standard priming mixture. The priming mixture is sealed into the cavity provided with a waterproof combustible seal.

A suitable adhesive for use in securing the projectile and primer in a propellant charge prepared from single base, double base, or triple base propellant compositions is nitrocellulose dissolved in methyl ethyl ketone. There are many adhesives that can be used with composite type propellants. The choice of the adhesive for use with composites will depend on the binder system employed for the composite propellant.

Table (I) summarizes ballistic results of the firing of telescoped rounds of caseless ammunition. In these tests the projectile was of the conventional 20 mm. type. The propellant charge was prepared from a granular double base propellant. The muzzle velocity and the chamber pressure resulting from the firing are substantially the same as for conventional metal cased rounds.

Ballistic Data irom Firing of Convention Round.

In the firing of a telescoped tround of caseles ammunition the projectile advances into the barrel of the firearm as a result of the force delivered to the base of the projectile following initiation of the primer. The seating of the projectile in the barrel of the firearm by action of the primer prior to complete initiation of the propellant charge prevents excessive gas flow ahead of the projectile resulting in ballistic performance comparable to that of conventional ammunition having the same weight of propellant charge. It is therefore important for optimum performance that the primer be chosen and sized so as to match the ignition characteristics of the propellant charge and to provide enough force to seat the projectile. It is generally desirable to position the primer close to the base of the projectile so that the initial force resulting from initiation of the primer is not dissipated in breaking up propellant which can be interposed between the primer and the base of the projectile as shown in FIG. 1. In a preferred embodiment of this invention the base of the projectile and the primer are connected by an axial cavity so as to maximize the force at the base of the projectile upon initiation of the primer.

It may be desirable in some instances to use an auxiliary ignition charge to aid in seating the projectile in the barrel of the firearm prior to complete ignition of the propellant charge. The auxiliary ignition charge consists of small granules of propellant which can be loosely packed in an axial cavity between the base of the projectile and the primer as illustrated in FIG. 2.

The propellant granules of the auxiliary ignition charge initially have a greater surface area than the propellant constituting the walls of the propellant charge and consequently are more readily ignited by the action of the primer. The combined force on the base of the projectile resulting from the initiation of the primer and the auxiliary ignition charge aid in seating the projectile in the barrel of the firearm prior to ignition of the entire propellant charge thereby minimizing loss of energy.

Suitable materials for use as auxiliary ignition charges include small granules of propellant of the same composition as the propellant charge as well as materials that are more readily ignited than the propellant charge. Examples of these auxiliary ignition materials include small granules of black powder, boron-potassium nitrate and double base smokeless powder.

The telescoped rounds of caseless ammunition of this invention can be prepared in any size desired. The amount of propellant in the propellant charge, the caliber of the projectile, and overall round configuration can be determined by one skilled in the art depending on such factors as the firearm for which the round is designed, and the desired range for the projectile.

As will be evident to those skilled in the art, variations and modifications can be made or followed in light of the foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure, or scope of the claims.

What we claim and desire to protect by Letters Patent 1. A telescoped round of caseless ammunition having in combination a propellant charge, a primer, and a projectile, the propellant charge having an axial bore equal to or greater in length than the length of the projectile, the projectile being housed completely within the axial bore of the propellant charge whereby the entire length of the projectile is surrounded by propellant, the primer being positioned behind the base of the projectile and in axial alignment therewith, and means for securing said primer and projectile within the propellant charge.

2. The telescoped round of caseless ammunition of claim 1 wherein the projectile is a subcaliber projectile held in a sabot and housed within the axial bore of the propellant charge.

3. The telescoped round of caseless ammunition of claim 1 wherein the propellant charge is prepared from molded granules of smokeless powder.

4. The telescoped round of caseless ammunition of claim 3 wherein the primer and the base of the projectile are connected by an axial cavity.

5. The telescoped round of caseless ammunition of claim 4 wherein the axial cavity is filled with an auxiliary ignition charge.

6. The telescoped round of caseless ammunition of claim 5 wherein the auxiliary ignition charge is comprised of small granules of double base smokeless powder.

7. The telescoped round of caseless ammunition of claim 5 wherein the projectile and primer are secured within the propellant charge with an adhesive.

'8. The telescoped round of caseless ammunition of claim 5 wherein the projectile is secured with a combustible cap and combustible plug within the axial bore of the propellant charge said propellant charge having a forward end and an aft end, said projectile being secured at the forward end of the propellant charge with the combustible cap which is adhesively secured to the propell i l cha ge and secured at the aft end of the propellant charge with the combustible plug which is adhesively secured to the propellant charge.

References Cited UNITED STATES PATENTS 6 3,345,945 10/1967 Quinlan et a1 102-38 3,398,684 8/1968 Kvaule 102-99 X OTHER REFERENCES Shokeless Shotgun Powders (S.S.P.); by Wallace Coxe, pub. E. I. du Pont de Nemours & Company, Inc., Wilmington, Del., 1933, p. 7.

ROBERT F. STAHL, Primary Examiner