BULLET

Abstract: In an ammunition round a bullet (1) has a plurality of elongate grooves (4) either helically formed or parallel with the longitudinal axis of the bullet and a sabot (6) which has a body (7) and fingers (9) which engage with the grooves and seal the bullet in a casing, the sabot having a slightly larger diameter than the bullet so that the sabot is engraved by the rifling slots in the barrel through which the round is to be fired, in order to rotate the bullet. A slug has grooves of the same kind as well as a sabot-like part or wad having fingers seated over the full length of the grooves, to prevent fitting of the slug on its way down the non-rifled barrel.

Description: BULLET The present invention relates to ammunition and is particularly useful in ammunition for use in conventional small arms weapons having rifled or non-rifled barrels. Conventional rifle bullets usually have a lead core with a surrounding copper jacket of a diameter which is slightly oversize with regard to the diameter of the barrel of the weapon with which it is intended to be used, the copper jacket of the bullet being engraved during its passage down the barrel of the weapon by the helical rifling grooves in the barrel. The bullet is spun by the rifling grooves to stabilize its flight, but a considerable proportion of the energy from the ignition of the cartridge containing the bullet is lost through friction between the bullet and the rifle barrel caused by the engraving of the bullet, the friction generating heat in the barrel. Particularly with weapons that fire fully automatically, heat generated by the friction of the bullets passing through the barrel can be a serious problem, causing the weapon to jam and firing to stop and, at its worst the barrel to bulge or burst. A conventional shotgun slug is a hollow, cylindrical lead cup with a domed end (ogival shape), but as a shotgun has no rifling grooves the. slug does not spin and is accurate only upto a range of about 100 metres or even less, partly due to the lack of spin and partly due to its unstreamlined shape which slows it quickly. According to a first aspect of the present invention an ammunition round comprises a casing for containing a propelling charge, a bullet which has a plurality of flutes or grooves in its outer surface extending helically around or substantially parallel to the longitudinal axis of the bullet, and a sabot into which the bullet seats and which seals the bullet into the casing, the sabot having at least a part with a diameter greater than the diameter of the bullet and a plurality of fingers engaging respective ones of the grooves in the bullet to cause the bullet to spin as the sabot is rotated by engagement with rifling grooves in a barrel through which the round is fired. According to a second aspect of the present invention an ammunition round comprises a casing for containing a propelling charge, a slug which has a plurality of flutes or grooves in its outer surface extending helically around or substantially parallel to the longitudinal axis of the slug, and a sabot into which the slug seats and which seals the slug into the casing, the sabot having a plurality of fingers seated in respective ones of the grooves in the slug, the fingers having a thickness substantially the same as the depth of the grooves and extending substantially the length of the slug thereby to stabilize the slug and prevent it from tilting off axis as it travels down the barrel through which it is fired. Preferably, in this case, when the slug is for a shotgun, the slug is formed from lead and weighs the same as the conventional shot within a shotgun cartridge. Preferably, the sabot comprises a resilient plastics moulding. The fingers of the sabot may be hollowed out to lighten the round if required. The invention also includes a bullet which has a plurality of flutes or grooves in its outer surface extending helically around or substantially parallel to the longitudinal axis of the bullet. Additionally the invention includes a sabot having a cylindrical body part and a plurality of fingers parallel to the axis of the body pdrt or helically formed about the axis. Such an ammunition round generates considerably less friction than a normal bullet in the barrel of a gun as the sabot is more easily engraved by the rifling grooves in the barrel and thus generates less friction as it travels along the barrel. The result is that a greater part of the initial energy, is put into the bullet as kinetic energy (velocity) and less of the initial energy is converted into heat in the barrel. Preferably the sabot has a body which is short in comparison with the length of the fingers, the fingers being flung radially outwards from the longitudinal axis of the bullet after it leaves the barrel by the spin of the bullet and sabot the outward motion of the fingers thereby releasing the sabot from engagement with the grooves of the bullet and allowing air pressure to disengage the sabot completely from the bullet shortly after leaving the barrel. The sabot may have an axial bore which allows the pressure of the propelling charge to force the sabot against the walls of the barrel into engagement with the rifling grooves. Alternatively, the rear of the bullet may have a tapered engagement with the body of the sabot to produce the same effect. By forming grooves in the surface of the bullet the bullet can be spin and/or fin stabilized during its passage through the air, when formed with helical grooves the spin rate being matched to the forward velocity 6f the bullet in flight so that as the forward velocity diminishes so does the spin rate. Preferably the bullet is formed of steel or a similar hard metal. By extending the grooves to the nose or leading end of the bullet the cross-sectional or frontal area of the bullet is decreased thus increasing armour penetration and range. According to a third aspect of the present invention an ammunition round comprises a casing for containing a propelling charge, a slug which has a plurality of flutes or grooves in its outer surface extending helically around or substantially parallel to the longitudinal axis of the slug, and a plurality of elongate elements seated in the grooves and having a thickness substantially the same as the depth of the grooves and extending substantially the length of the slug thereby to stabilize the slug and prevent it from tilting off axis as it travels down the barrel through which it is fired. Preferably in this case the slug and elements are formed of steel. Three examples of ammunition rounds constructed in accordance with the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a side elevational view of a bullet; Figure 2 is a section on the line fII-II in Figure 1; Figure 3 is a side elevational view of a sabot; Figure 4 is an end elevational view on arrow IV in Figure 3t Figure 5 shows the sabot assembled on the end of the bullet and the assembly fitted into the end of a casing; Figure 6 is a cross-section of a shotgun slug; Figures 7a and 7b are an axial section and a radial section through a first shotgun cartridge; Figure 7c is an elevation of the sabot of the cartridge of Figures 7a and 7b; and, Figures 8a and 8b are a radial section and axial section through a second shotgun cartridge. When seen in elevation as in Figure 1, the bullet 1 has a conventional outline having a parallel sided portion 2 and a tapered nose 3. However, unlike a conventional bullet the surface iof the bullet is not a smooth cylindrical/tapered surface, but rather a plurality of V-shaped grooves 4 are formed extending parallelto the longitudinal -axis 1' of the bullet, in the present embodiment there being four grooves and each of the grooves having a. substantially 90.0 included angle at. its base. This leaves, therefore, four elongate flanges .5 in a cruciform shape as shown in Figure 2 The grooves 4 extend to the nose 3 of the bullet and the bullet thus presents a much smaller frontal area than a: conventional bullet with a corresponding increase in the ability of the bullet to penetrate armour plating or the like. At the end of the bullet remote from the. nose, hereinafter called the rear, a sabot formed of as resilient plastics material such as nylon, is mounted in use. The. sabot 6, as seen in Figure 3 and 4, has a generally cylindrical body part 7 with an enlarged diameter raised portion 8 which is of a diameter just slightly larger than the nominal diameter- of the bullet 1. This is best seen in Figure 5. Extendingfrom the body part 7 are a plurality in the present embodiment four, fingers 9, each of which extend generally parallel to the central axis (7') of the cylindrical body part 7 and each of, which, when, viewed in cross section as in Figure 4, comprises a substantially 900 segment which is a close fit within a respective groove 4 in the bullet. At its free end each leg has a reduced thickness portion 10 which enables a casing 11, into which the assembly of the sabot and bullet are mounted together, to be crimped onto the assembled bullet 1 and sabot 6 (as shown at 12) at its smaller diameter end portion 13 into which the assembly of bullet and sabot is fitted. The plastics material of the sabot seals the casing at the crimp to make the round watertight during storage. The fingers of the sabot fill the grooves of the bullet behind the crimp to prevent gas leakage through the grooves at ignition. By way of example, a standard 5.56 military or .223 Remington barrel has a nominal bore diameter of .219 inches and the diameter to the base of the rifling grooves is nominally .224 inches, the width of the rifling grooves -being .07 inches. The diameter of a bullet (as shown in the drawings) to fit is of nominal diameter .21875 inches and the width of the flanges 5 is .060 inches. The overall length of the bullet 1 is 1.127 inches. The nominal diameter of the sabot body 7 is .216 inches and that of the enlarged diameter portion 8 .224 inches, the length of the portion 8 being .062 inches and the length of the whole of the body 7 .125 inches. In Figures 6 to 8 parts similar to those in Figures 1 to 5 are given the same reference number. The slugs 1 have an ogival shape, the ratio of the length of the slug to its diameter approaching unity. Each of the fingers 9 in the first slug has a hollow in its radially outer surface to lighten the sabot in order to reduce the weight of the cartridge to that of a conventional cartridge. The metallic elements 14 shown in figures 8a and 8b comprise steel elements of equilateral curved triangular shape fitting congruently within the grooves 4 in the second slug 1.

Claims: CLAIMS 1. An ammunition round comprising a casing (11) for containing an propelling charge, a bullet (1) which has a plurality of flutes (4) or grooves in its outer surface extending helically around or substantially parallel to the longitudinal axis of the bullet (1) and a sabot (6) into which the bullet (1) seats and which seals the bullet into the casing (11), the sabot (6) having at least a part (-8) with a diameter greater than the diameter of the bullet (1) and a plurality of fingers (9) engaging respective ones of the grooves (4) in the bullet (I) to cause the bullet to spin as the sabot (6) is rotated by engagement with rifling grooves in a barrel through which the round is fired. 2. An ammunition round comprising a easing (11) for containing a propelling charge, a slug (1) which has a plurality of flutes or grooves (4) in its outer surface extending helically around or substantially parallel to the longitudinal axis of the slug, and a sabot (6) into which the slug seats and- which seals the slug into the casing, the sabot having a plurality of fingers (9) seated in respective ones of the grooves in the slug, the fingers having a thickness substantially the same as the depth of the grooves and extending substantially the length of the slug thereby to stabilize the slug and prevent it from tilting off axis as it travels down the barrel through which it is fired. 3. An ammunition round comprising a casing (11) for containing a propelling charge, a slug (1) which has a plurality of flutes or grooves (4) in its outer surface extending helically around or substantially parallel to the longitudinal axis of the slug, and a plurality of elongate elements (14) seated in the grooves and having a thickness substantially the same as the depth of the grooves and extending substantially the length of the slug thereby to stabilize the slug and prevent it from tilting off axis as it travels down the barrel through which it is fired. 4. A round according to any of the preceding claims, wherein each groove has a substantially V-shaped cross section. 5. A round according to any of the preceding claims, wherein said bullet is made of steel. 6. A round according to claim 1 or claim 2 or any claim when dependant thereon, wherein the sabot comprises a body part (7) which is short in comparison with the length of the fingers (9). 7. A round according to claim 1 or claim 2 or any claim when dependant thereon, wherein the sabot (6) comprises a resilient plastics moulding. 8. A, round according to claim 1 or claim 2 or any claim when dependant thereon, wherein each of the fingers (9) of the sabot has a reduced portion (10) adjacent its free end. 9. A round according to claim 1 or claim 2 or any claim when dependant thereon, wherein the fingers (9) of the sabot each have a part-cylindrical radially outer surface (9'), the fingers filling the respective grooves or flutes (4), and with the portions (5) of the bullet between the grooves, forming a solid substantially circular section. 10. A round according to claim I or claim 2 or any claim when dependant thereon, wherein the sabot (6) comprises a cylindrical body part (7) having an enlarged diameter raised portion (8), the diameter of which is greater than the diameter of the bullet (1). 11. A bullet or slug (1) having a plurality of flutes or grooves (4) formed in its outer surface extending helically around or substantially parallel to the longitudinal. axis of the bullet. 12. A sabot (6) having a cylindrical body part (7) and a plurality of extending fingers (9) parallel to the axis of the body part or helically formed about said axis.

Inventors: SULLIVAN, LEROY JAMES
Applicants: BRANSCOMB CORPORATION N.V.
Application year: 1983
Main classification: F42B31
IPC codes: F42B7, F42B14, F42B5, F42B10, F42B12