US3828678A

US3828678A - Jacketed bullet

Info

Publication number: US3828678A
Application number: US00290961A
Authority: US
Inventors: J Bernath
Original assignee: KOTE CORP DU
Current assignee: DU KOTE CORP US; KOTE CORP DU
Priority date: 1972-09-21
Filing date: 1972-09-21
Publication date: 1974-08-13
Anticipated expiration: 1991-08-13

Abstract

A self-lubricating, vapor trailing ammunition round including a jacket about the forward portion of the bullet and extending rearwardly about the forward portion of the casing, said jacket comprising an inner layer of plastic lubricous material with a low latent temperature of vaporization and a thin outer layer of hard, dry, frangible material. The jacket seals the annulus between the casing the the bullet. The jacket material about the casing lubricates the chamber of the fire arm on which it is engaged to prevent freezing of the casing on the chamber. A portion of the jacket material on the bullet lubricates the bore of the fire arm to extend bore life and creates an improved gas seal. A portion of the jacket remains on the bullet after it leaves the fire arm and is vaporized by friction heat between the jacket material and the air to produce a vapor trail.

Description

baited Ettes Patent [191 Eernath Aug. 13, 1974 JACKETED BULLET John Bernath, c/o Du-Kote Corporation, 39651 Esplanade, San Jacinto, Calif. 92382 Filed: Sept. 21, 1972 Appl. No.: 290,961

Inventor:

US. Cl. 102/92, 102/38 Int. Cl. F42b 31/02 Field 05 Search 102/92, 92.1-92.7,

OTHER PUBLICATIONS Organic Chemistry by E. Wertheim, 3rd Edition, McGrawI-Iill Pub. Co. 1951, p. 247. Primary ExaminerRobert F. Stahl [5 7] ABSTRACT A self-lubricating, vapor trailing ammunition round including a jacket about the forward portion of the bullet and extending rearwardly about the forward portion of the casing, said jacket comprising an inner layer of plastic lubricous material with a low latent temperature of vaporization and a thin outer layer of hard, dry, frangible material. The jacket seals the annulus between the casing the the bullet. The jacket material about the casing lubricates the chamber of the fire arm on which it is engaged to prevent freezing of the casing on the chamber. A portion of the jacket material on the bullet lubricates the bore of the fire arm to extend bore life and creates an improved gas seal. A portion of the jacket remains on the bullet after it leaves the fire arm and is vaporized by friction heat between the jacket material and the air to produce a vapor trail.

10 Claims, 6 Drawing Figures IIMII'I'II",

JACKETED BULLET This invention has to do with ammunition for firearms and is more particularly concerned with a novel jacketed bullet or a jacket like coating therefor.

In the art of firearms, ammunition comprising elongate cylindrical, metallic shells or casings with front and rear ends, ignition devices or primers at the rear end of the casings, metal projectiles or bullets releasably engaged in the front ends of the casings and charges or supplies of explosive powder in the casings between the primers and the bullets is commonly provided for use in hand guns and rifles.

The ordinary firearm, such as a rifle, in which ammunition of the character referred to above is used comprises an elongate barrel with front and rear ends, a central longitudinal bore with a plurality of circumferentially spaced, radially inwardly projecting and longitudinally extending, helical rifling ribs with bulletengaging lands. The front end of the bore is open. The rear end of the barrel has a chamber communicating with the bore to receive and contain the casings of rounds of ammunition arranged and fired in the rifle.

Rearward of the barrel and chamber is a breach structure or mechanism provided to effect the engagement of ammunition into the chamber and barrel for firing, and for the extraction of the casings of spent or fired ammunition fromthe chamber. A firing mechanism comprising a trigger-controlled firing pin and operable to strike the primer of the ammunition to effect detonation and oxidation of the power in the ammunition is provided. Firing of the ammunition results in the generating of gases which force the bullets from engagement with their casings, longitudinally through and from the rifled bore of the barrel.

The details of construction, proportioning and configuration of the various components of ammunition of the character referred to above are subject to considerable and wide variations. With few possible exceptions, the invention here provided is compatible with and can be effectively related to all commonly used structures, sizes and forms or styles of ammunition.

In the ordinary use of rifles, there is a tendency for the shells to become jammed or to stick in the chambers. The above is due to the fact that when the ammunition is fired, the casings are expanded in the chambers by the gas pressures. The casings are intended to yieldingly expand into tight supported engagement in the chamber under the gas pressure generated, as the ammunition is fired and to thereafter contract from such engagement to permit their easy extraction therefrom. In practice, sufficient contraction does not always occur and the casings stick in the chambers. This is frequently due to the heat expansion of the metals defining the chambers and the casings and commonly occurs during repeated or rapid firing of the rifles.

The above sticking or jamming of casings in the chambers of rifles can be prevented by the application and/or use of a suitable lubricant in the chambers and- /or about the casings, but such has been considered impractical due to the fact that suitable lubricants tend to be sticky and to collect and carry foreign matter which would bring about far more serious results than occasional jamming. Further, available lubricants considered suitable for use in firearms are products which tend to burn and break down in such a manner as to foul and gum up the chambers and bores of gun barrels when present in suitable quantity to effect lubrication and when subjected to the temperatures encountered during the firing of ammunition.

In the art, at present, it is considered proper and accepted practice to maintain the chambers and bores of rifles and the ammunition therefor, clean and dry. In those cases where lubricous materials are employed, they are employed primarily as protective coatings to prevent rust and oxidation of the metal surfaces and are preferably light lubricants applied as thinly or lightly as is practical.

In the normal use of rifles, the bullets, as they are moved through the bores of the barrels establish sliding bearing engagement on the lands of the helical rifling ribs therein and are caused to rotate thereby. The noted sliding of the bullets on the lands results in a transfer of metal of the bullets (which are soft metals such as lead or copper) onto the surface of the lands and on or at the leading sides of the helical ribs, i.e., the sides of the ribs toward which the bullets advance. As a result of such transfer of metal, the bore of rifles becomes fouled or leaded up at a rapid rate and must be regularly taken out of service and cleaned. In addition to leading up the barrels, due to the lack of suitable lubrication, considerable wearing of the lands or ribs in the bores occurs with the result that a proper fit between bullets and the rifling lands is soon lost and accuracy of the firearms rapidly deteriorates.

In practice, the bore of an Armalite AR 18 rifle should be cleaned after every 200 or 300 rounds of ammunition has been fired therethrough and is generally worn out and must be replaced after approximately 5,000 rounds.

It has long been recognized that if a bore and/or the bullets of rifle ammunition .could be effectively lubricated, leading up of the bore could be eliminated and wearing of the bore, that is, wearing of the rifling lands could be materially reduced. In spite of the above, due to the over balancing adverse effects which are experienced in the use of lubricants, such as burning of the lubricants and the resulting building up of carbon and varnishes in the chamber and bore, as well as the transporting of foreign matter picked up by lubricants and carried into the chamber and bore thereby, it is generally accepted practice to avoid the use of lubricants and to operate rifles with the chambers, bores and the ammunition in as dry and clean a condition as is possible, free of any appreciable and/or effective quantities of lubricant.

In the art of ammunition, there exists a special class of bullets termed tracer bullets, which bullets have cavities entering their rear ends and in which a body of combustible material, such as phosphorous, is deposited. The combustible material is ignited by the burning powder in the casings and continues to burn as the bullets travel through the air, creating a visible flame at the rear of the bullet and a trail of glowing particles and/or gases which can be visually detected or watched. Withthe use of tracer bullets, one can view the course of bullets leaving his firearm and can adjust the direction of fire accordingly and to effect hitting a desired target. Such bullets constitute a supplement or substitute for the aiming sights normally provided on firearms.

Ordinary tracer bullets have been outlawed for civilian use due to their incendiary nature and the likelihood that the combustible material they carry will contact and ignite combustible materials along the paths of the bullets. Accordingly, the ordinary tracer bullet is restricted for use by the military.

As regards military use of tracer bullets, they are hazardous or dangerous to use since while they show the operator of the rifle from which they are fired where the bullets are going, they also show an enemy exactly where the bullets are coming from and expose the position of the operator.

While some tracer bullets, for large bore weapons, are large enough to carry a sufficient supply of combustible material so that a smoke trail of sufficient extent and density for daylight viewing is created, such bullets for small bore weapons or rifles do not leave an adequate trail for daylight viewing.

Still further, tracer bullets, as now provided by the art, are not considered effective or damaging projectiles since they are hollowed out to accommodate the combustible material and are so light when that material has burned away to any appreciable extent that they lose effective penetrating power.

As a result of the above, ammunition rounds with tracer bullets are never used exclusively, but are mixed with a larger quantity of numbers of rounds with regular bullets, in a spaced sequential pattern and are utilized for the purpose of indicating, generally, where the regular bullets, fired sequentially therewith, are going.

Since tracer bullets are different in weight than the regular bullets with which they are fired and since their weight varies, their trajectory is entirely different than the regular bullets, with the end results that they do not really show where the regular bullets are going, but, at best, simply indicate the general direction in which the regular bullets are directed.

A principal object and feature of the present invention is to provide a lubricous jacket for bullets which effectively lubricates the bore of a rifle from which it is fired to materially extend the bore life thereof and which lubricates the chamber of the rifle to prevent freezing of casings therein.

It is an object of this invention to provide a nonincendiary tracer bullet having a jacket composed of materials which vaporize under heat generated between the bullet and air to leave a visible vapor trail.

Another object and feature of the instant invention is to provide a tracer bullet of the character referred to wherein the material which vaporizes is such that it will not vaporize until the bullet has traveled a substantial and predeterminable distance from the rifle and a distance for sufficient heat to be generated by the friction of the air to effect vaporization of said material whereby the vapor trail left by the bullet is effective to show the operator of the gun where the bullet is directed, but is not such that it will disclose to an enemy or others where the rifle and operator are located.

It is an object and feature of this invention to provide a tracer bullet of the character referred to which is not especially made to hold a supply of combustible material, but which is a regular or normal bullet of normal weight with a substantially normal trajectory and normal impact and/or penetrating characteristics.

Yet another object and feature of this invention is to provide a jacketed bullet, or a jacket-like coating for bullets, of the character referred to which has an exterior surface which is sufficiently hard, smooth, dry and non-sticky that it will withstand normal and reasonable handling and abuse and will not collect and/or carry foreign matter which is apt to cause damage to a rifle in which the bullet is engaged and fired.

An object and feature of my invention is to provide a bullet jacket of highly lubricous material, which material, if left or deposited in a bore through the bullet is fired, will vaporize cleanly in the presence of the heat generated in the rifle and is therefor such that it will not burn and leave harmful or undesirable residue in the bore.

An additional object and feature of my invention is to provide a jacket or jacket-like coating of the character referred to which effectively protects the bullet from moisture and which effectively hermetically seals the interior of a related casing, about the forward open end thereof adjacent and about the bullet.

It is an object and feature of my invention to provide a jacket structure or jacket-like coating of the character referred to which is extremely easy and economical to establish and/or apply to ammunition.

The foregoing and other objects and features of my invention will be fully understood and will become apparent from the following detailed description of the invention throughout which description reference is made to the accompanying drawings in which:

FIG. 1 is a side elevational view of a round of ammunition embodying my invention;

FIG. 2 is an enlarged detailed sectional view of the structure shown in FIG. 1, taken as indicated by line 2-2 on FIG. 1;

FIG. 3 is a view illustrating the structure shown in FIG. 2 related to the chamber and bore of a firearm;

FIG. 4 is a sectional view taken substantially as indicated by line 44 on FIG. 3;

FIG. 5 is an elevational view substantially illustrating one state or condition of the bullet after it leaves a firearm; and

FIG. 6 is a diagrammatic view of a method of establishing my new structure.

When viewing and considering the drawings, it is to be understood that the proportioning of elements, parts and/or portions of the structure illustrated are not necessarily correct and have, where appropriate, been exaggerated so as to better illustrate the invention.

Referring to the drawings, I have shown the invention embodied in and/or with a standard or conventional round of ammunition A such as is used in military and- /or hunting rifles.

The ammunition round A includes an elongate cylindrical shell or casing C having an open front end 10 and a closed rear end 11, and a projectile or bullet B engaged in the open front end 10 of the casing.

The casing C is a hollow shell-like part established of metal, preferably brass. The rear end portion of the casing is formed to establish a radially outwardly opening extractor groove 12 and has a central rearwardly opening recess 14 in which a detonator cap D is engaged. The cap D is hermetically sealed in the recess 14 by the application of a suitable sealing compound (not shown) in the recess and about the cap.

In the drawings and for the purpose of illustrating a preferred form and carrying out of the invention, I have elected to show the casing C as being that form or class of casing which is characterized by a forward neck portion of reduced diameter to receive and hold or carry the bullet B.

The bullet is an elongate metal projectile having a substantially straight cylindrical rear portion and a forwardly convergent cylindrical front portion 21 terminating at a substantially pointed target or object engaging front end.

The rear portion 20 of the bullet is of a diameter which permits that portion of the bullet to be freely slidably engaged in the front portion of the of the casing C, at its open front end 10. The bullet B is releasably gripped and/or held in the casing by the front edge portion X of the casing which is suitable crimped, radially inwardly into tight engagement with the rear portion of the bullet.

In the case illustrated, the cylindrical rear portion of the bullet is provided with an annular, radially outwardly opening groove 25 to receive and in which the crimped portion or edge X of the casing is engaged.

The groove 25 is dimpled, or, in effect, serrated about its circumferential extent to define malleable or readily formable projections which the crimped edge of the casing forms to establish snug and/or or tight mating engagement between the bullet and casing. While the serrated groove 25 in the bullet effects desired engagement with the crimped edge of the casing, it pre vents the establishment of a moisture proof seal between the bullet and the casing.

In some ammunition, the bullets are ungrooved and are simply press fitted into the casings to be held thereby, or the casing is crimped to engage the straight cylindrical surfaces of the bullets. In such structures, while a seal is more readily established between the bullets and the casings, any seal which is established is not sufficiently strong or tight to prevent the movement of moisture between the bullets and casings, and into the casing.

In FIG. 2 of the drawings, the clearance between the rear portion of the bullet and the forward portion of the casing, rearward of the crimped edge thereof is exaggerated or shown excessive for purposes of illustration.

The interior of the casing C, rearward of the bullet, is filled with suitable explosive powder P.

The ammunition round A thus far described is a typical, conventional type and/or class of ammunition.

The round A, as shown in FIGS. 3 and 4 of the drawings, is, when used, engaged in the barrel R of a related firearm or rifle with the front portion of the bullet projecting forwardly from the casing C and entered in the rear end of a longitudinal bore extending through the barrel. The front portion of the casing C is engaged in an enlarged casing receiving chamber 31 at and communicating with bore 30.

The bore 30 is provided with a plurality of circumferentially spaced radially inwardly projecting, longitudinally extending, helical rifling ribs 32 with substantially radially inwardly disposed, flat, lands 33. In practice, the lands can, as shown, be inclined planes with respect to their radial planes whereby they are greater in radial extent along their longitudinal leading edges than along their trailing edges, with respect to the movement of bullets relative thereto.

The bore 30 is greater in diametric extent than the bullet B and the radial extent of the rifling ribs 32 is such that the lands 33 thereof establish positive frictional sliding engagement with the rear portion of the bullet B and in such a manner that they turn or rotate the bullet in and relative to the bore 31 as the bullet is moved longitudinally therethrough.

The extent to which the rifling ribs or lands engage the bullets is sufficient to notch and/or score the exterior surface of the bullet, substantially as indicated at Z in FIG. 5 of the drawings.

The chamber 31 is shaped or formed similar to the exterior of the casing C and is slightly larger than the casing whereby casings can be freely engaged in and extracted or removed from the chamber, but not so large that when the round is fired and caused to expand, the chamber will not engage and support the exterior of the casing and prevent its rupturing. Accordingly, substantial clearance exists between the surfaces of the chamber and the casing before the ammunition round is fired. When the round is fired, such clearance is substantially eliminated. After the round is fired, the casing, due to the resiliency of the metal, contracts to near its original size and shape. It does not return completely to its original size and shape and frequently will remain in sufficient partial contact with the chamber to be frictionally held or stuck therein.

The above noted structural and cooperative relationship of the ammunition round A and the rifle barrel R is illustrative of a standard or conventional combination and relationship of parts in the art to which my invention relates and in which or with which my invention can be advantageously incorporated or related.

The instant invention includes an ammunition round, such as the round A illustrated in the drawings and described above and in addition thereto and/or in combination therewith, includes a jacket .I on and about the forward portion 21 of the bullet B. The jacket I can continue rearwardly about the forward part of the rear portion 20 of the bullet and can further extend rearwardly about the forward portion of the casing C.

The jacket J includes a body or inner layer L of soft lubricous material of substantially uniform thickness on and about the portion of the bullet which the jacket encloses and a hard, dry, frangible outer layer, shell or skin S about the inner lubricous layer L.

The lubricous material is material having excellent lubricating characteristics between bearing metal parts or surfaces and which, under normal conditions and to temperatures up to at least 200 F is a stable, non-fluid or solid material. It is sufficiently plastic that it will, under appreciable applied force readily flow. Further, the material of the layer L is such that when it is heated to, for example, 500 F. to 700 F it vaporizes.

It is important that the material of layer L vaporizes at a temperature well below that temperature where it will burn and so that it will not carbonize or and/or leave appreciable deposits of carbon and/or varnishes on heated surfaces with which it comes into contact.

The lubricous layer L is established of hydrogenated, organic oil, such as vegetable oil.

In the process of hydrogenating organic or vegetable oils, that is, in the process of scrubbing and mixing such oil with hydrogen gas, the viscosity of the oil is increased to an extent that it becomes non fluid and is in a plastic solid state. Further, the range of temperatures at which the oil will liquify vaporizes and burn is increased or elevated.

In carrying out of my invention, the solid, plastic, hydrogenated vegetable oil is hydrogenated to an extent where its burning temperature is well below and its melting and vaporizing temperatures are within the range of temperatures encountered in the bore and chamber of a gun and within the range of temperatures generated by the friction between the bullet and the air as the bullet travels therethrough.

When such oil is hydrogenated to within the temperature range indicated above, the viscosity is quite high and it is in a rather hard or still plastic state.

In addition to the above hydrogenated oil, the layer L includes a binder of Carnuba wax which serves to further stiffen the hydrogenated oil. In practice, the layer L can contain or include approximately /4 hydrogenated vegetable oil and A carnuba wax. Carnuba wax, in a pure state, is a hard, extremely brittle material with a vaporization point near l,OO F., and is generally considered to be totally inappropriate as a lubricant and an incompatible, if not a deleterious substance for use in firearms.

It has not been determined What molecular, grain and/or crystalline structure the noted oil and wax mixture creates, but the material is quite hard, stiff and wax-like. It is a considerably stiffer and harder material than the hydrogenated oil alone. Further, when the oil is vaporized, the carnuba wax is apparently vaporized with it or is present in such finely divided particles that it is effectively carried away by the vaporized oil. If traces of the wax are left and are to be found in the barrel and/or chamber of a gun in which the ammunition A is fired, it is in such small quantities and in such a fine state that it is substantially non-detectable and insufficient to cause any adverse effects.

The outer layer or skin S of the jacket structure J is a hard, dry, thin, frangible layer or skin of carnuba wax. The skin S is sufficiently hard, dry and tough that it does not pick up and carry foreign matter, and is not subject to being penetrated or broken down to an appreciable extent through ordinary handling. It is sufficiently hard and tough or strong so that when it is related to or combined with the layer L and when normal effort is exercised to remove the jacket J from a related bullet, one must engage the jacket with a rather hard, sharp or fine-edged object, such as his fingernail, and scrape the jacket free from the bullet with deliberately applied and directed force.

The layers L and S of the jacket J are established and applied to the bullet B and casing C of the ammunition round A by dipping and removing the bullet end of the round into and from a body of heated molten, oil and wax mixture.

After the bullet is dipped and the mixture clinging thereto cools, the carnuba wax at the exterior of the coating and which has a higher melting point than the oil, solidifies first, coalescing with other of said wax adjacent to the surface to create the thin, hard, frangible skin S.

The skin S is extremely thin, is hard and is frangible. The skin S is such that when it is forcibly acted upon, it breaks up in such a manner that it cannot be readily segregated from the material of the layer L which is forcibly acted upon therewith and, like that wax within the oil of the layer L, is carried away by the oil when the oil is vaporized.

The skin S is extremely thin and need only be sufficiently thick to provide the inner layer L with a dry, impervious skin which is non-sticky and on which foreign matter will not stick to foul the ammunition.

In practice, and as illustrated in FIG. 6 of the drawings, the bullet B of the round A is dipped in the hot molten mixture up to the front end of the casing C. Capillary attraction causes the molten material to flow up about the casing about inch.

The molten mixture is at about 300 F. (below the cook-off temperature of the ammunition which is about 350 F.) The dip period is sufficient to heat the round enough to drive the moisture ladened air from the interior of the shell. (This can be detected by bubbles escaping from between the casing and bullet).

When the round is extracted from the oil and wax and is cooled, the portion of the jacket about the open front end of the casing hermetically seals the casing.

When ammunition round A, as provided by the present invention, is advanced into engagement in the chamber 31 and bore 30 of a related barrel R, the portion of the jacket J about the rear portion of the bullet is engaged by the rifling ribs 32 in the bore and is displaced thereby, lubricating the ribs and tending to deposit certain of the material of the jacket in the chamber. The portion of the jacket about the forward end of the casing occurring in the chamber combines with that material that is displaced therein by the rifling ribs (if any). (See FIGS. 3 and 4 of the drawings).

When the round is fired, the casing expands and the material of the jacket in the chamber is displaced in the chamber and about the casing and in such a way as to effectively lubricate the chamber and the casing and to prevent the casing from sticking in the chamber.

The heat generated by the burning of the powder heats the casing sufficiently to vaporize the lubricous material and to such an extent that it rapidly disappears. As the lubricant vaporizes and disappears, it carries with it considerable heat, with the result that the rifle or gun heats less than a gun firing conventional ammunition.

As the bullet B is forced longitudinally through and from the bore 30 of the barrel R, the jacket material lubricates the lands 33 of the rifling ribs 32. The heat of the expanding burning powder and gases vaporizes the jacket material deposited or left in the barrel and it has been determined that the vaporized material tends to pick up ash or residue from the powder and to carry it out of the barrel as it vents therefrom.

In a test made with my new ammunition, 600 rounds were fixed in time and rapid fire groups in and from an Armalite AR 18 rifle. The bore of the rifle was, prior to the commencing of the test, dirty and in need of cleaning. Following the test, the barrel was clean and not in need of cleaning.

In the 600 rounds fired, not one round of ammunition became stuck in the gun, despite the fact that every effort was made to create those firing conditions where jamming, due to excessive heating of the rifle, normally occurs.

When the bullet leaves the front or muzzle end of the barrel, the jacket J on the forward tapered portion thereof and which is not engaged by the rifling ribs, remains in tack, substantially as indicated in FIG. 5 of the drawings.

As the bullet travels through the air, friction heat is generated which heat is conducted through the skin S to the layer L. As the heat increases, the material of the layer L vaporizes leaving a visible trail behind the bullet.

The heat which vaporizes the jacket material left on the bullet B after it leaves the bbarrel of the gun does not build up sufficiently to vaporize the material until it has traveled a substantial distance.

In practice, and by varying the heat range of the jacket material, it can be made so that it will commence to vaporize when it reaches a certain distance from the gun and where an anticipated or known temperature will be generated. For example, it can be made to vaporize when the bullet is about 25, 50, 75 or 100 yards from the muzzle of the gun.

The vapor trail left by the jacket J is substantially white, dense and visible.

By varying the thickness of the jacket, the denseness of the trail and its potential length can be varied as desired.

In practice, by varying or changing the period of dipping to establish the jacket, its thickness can be effectively varied and its thickness throughout its longitudinal extent can be varied. For example, the thickness of the jacket at the front portion of the bullet can be made thicker than the rear portion of the jacket. The front portion of the jacket might be 1 /2 mils and the rear portion thereof /2 mil in thickness. or the entire jacket may be established at /2 or 1 mil in thickness, as desired or as circumstances require.

The principal advantage to be found in the use of my new ammunition round is the extention of bore life. Anticipated bore life through use of my new ammunition is at best two times and in many instances three or more times the anticipated bore life if conventional ammunition is used.

The second most important advantage found in the use of my new ammunition is lubrication of the chamber which effectively prevents freezing or jamming of casings in the chamber.

The other advantages to be found in and by the use of my new ammunition, such as the tracer effect afforded and other advantages not specifically mentioned are generally of secondary significance though such advantages are or can be of primary importance when and in those situations where such advantages are particularly sought to be attained.

Having described my invention, I claim:

1. Self-lubricating vapor-trailing ammunition round for use in a barreled firearm, comprising an elongate, cylindrical, hollow casing with an open front end and a closed rear end, an elongate bullet with a substantially straight cylindrical rear portion engaged in the open front end of the casing and a forwardly convergent front portion projecting forwardly from the casing,

explosive power within the casing, detonator means at the rear end of the casing, and a jacket having an inner layer of hydrogenated vegetable oil on and about the forward portion of the round, a thin and outer skin of normally dry, hard frangible wax, said vegetable oil being hydrogenated to that extent where it vaporizes at that range of temperatures generated by the friction between the bullet and ambient air after the round has been detonated in a related barreled firearm and the bullet leaves the barrel thereof.

2. A structure as set forth in claim 1 wherein the jacket is coextensive with the front portion of the bullet.

3. A structure as set forth in claim 1 wherein the jacket is coextensive with the portion of the bullet extending forwardly from the casing.

4. A structure asset forth in claim 1 wherein the jacket is coextensive with the portion of the bullet extending forwardly from the casing and extends rearwardly therefrom about the forward portion of the casing to seal between the bullet and the casing and to lubricate a chamber in the firearm in which the casing is engaged.

5. A structure as set forth in claim 1 wherein the thin, hard and dry, frangible outer skin is established of carnauba wax and has a higher melting point than the vegetable oil.

6. A structure as set forth in claim 1 wherein the wax establishing the outer skin extends into the inner layer of hydrogenated vegetable oil to reinforce and contain said layer.

7. A structure as set forth in claim 6 wherein said jacket structure comprises about three-quarters hydrogenated vegetable oil and one-quarter carnuba wax.

8. A structure as set forth in claim 6 wherein the jacket is coextensive with the front portion of the bullet.

9. A structure as set forth in claim 7 wherein the jacket is coextensive with the front portion of the bullet.

10. A structure as set forth in claim 9 wherein the jacket is coextensive with the portion of the bullet extending forwardly from the casing and extends rearwardly therefrom about the forward portion of the casing to seal between the bullet and the casing and to lubricate a chamber in the firearm in which the casing is engaged.

Claims

1. Self-lubricating vapor-trailing ammunition round for use in a barreled firearm, comprising an elongate, cylindrical, hollow casing with an open front end and a closed rear end, an elongate bullet with a substantially straight cylindrical rear portion engaged in the open front end of the casing and a forwardly convergent front portion projecting forwardly from the casing, explosive power within the casing, detonator means at the rear end of the casing, and a jacket having an inner layer of hydrogenated vegetable oil on and about the forward portion of the round, a thin and outer skin of normally dry, hard frangible wax, said vegetable oil being hydroGenated to that extent where it vaporizes at that range of temperatures generated by the friction between the bullet and ambient air after the round has been detonated in a related barreled firearm and the bullet leaves the barrel thereof.

4. A structure as set forth in claim 1 wherein the jacket is coextensive with the portion of the bullet extending forwardly from the casing and extends rearwardly therefrom about the forward portion of the casing to seal between the bullet and the casing and to lubricate a chamber in the firearm in which the casing is engaged.