PLASTIC-COATED BULLET

Abstract: A bullet which is particularly suitable for use in situations where it is desired to disable a living target in a ''close quarters'' situation, comprises a body part made of a material having a density lying in the range 5.0 to 1.5 grams per c.c. and preferably in the range 2.6 - 2.9 grams per c.c., e.g. an aluminium base alloy and the body part may have a coating of synthetic plastics material. The bullet may have a planar leading end surface followed by a frustoconical part, a shoulder of planar annular shape, and a cylindrical part.

Description: PLASTIC - COATED BULLET Description of Invention This invention relates to bullets. An object of the invention is to provide a new and improved bullet, and a more specific object is to provide a bullet which is particularly suitable for use in situations where it is desired to disable a living target in a "close quarters" situation. According to one aspect of the invention, we provide a bullet comprising a body part made of a material having a density lying in the range 5.0 to 1.5 grams per c.c. Preferably, the density lies in the range 2.6 - 2.9 grams per c.c. Preferably the material of which the body part is made comprises aluminium base alloy. The aluminium base al loy may comprise not less than 50-60% aluminium. The aluminium base alloy may comprise:- Silicon 0.25% max. Iron 0 0% max. Copper 0.05% max. Manganese 0.05% max. Magnesium 0.05% max. Zinc 0.07% max. Titanium 0.05% max Incidental Impurities 0.03% max. (each impurity) Aluminium Balance and not less than 99.5% The body may have a coating of synthetic plastics material. The synthetic plastics material may comprise PTFE but preferably comprises nylon. The plastics material may have been applied by an electrostatic powder coating operation followed by baking. The bullet may have a nose of semi-wad cutter configuration. By semi-wad cutter configuration we mean a configuration having a planar circular leading end surface followed by a frusto-conical side surface which increases in diameter away from the leading end surface. A shoulder of planar annular shape may be provided between the larger diameter end of the frusto-conical side surface and a following cylindrical side surface of the bullet. A bullet embodying the invention is of relatively light weight and hence a relatively large number can be carried conveniently without weighing down the carrier or without being noticed. The bullet avoids leading of the bore of a weapon from which the bullet is fired and does not give rise to toxic gases such as lead vapour which is significant, particularly when a lead bullet is used in a enclosed environment such as indoor shooting ranges. Because of its low density, very little recoil is encountered and hence the time taken to return the aim of the weapon from which the bullet is shot back to the target line is very small and indeed for all practical purposes a user finds that his weapon is not pushed off target by the recoil. The wounding capability is very high. It has been found on tests conducted by firing the bullet into Swedish soap, which simulates the effect of firing the bullet into a human body, that a wound eight times the volume of a wound produced by a conventional lead bullet is made. It has also been found that an exit wound is not produced thereby avoiding risk of any secondary target behind a primary target being shot. In addition, the possibility of use of the bullet in an enclosed environment, such as in a pressurised aircraft cabin, arises since the bullet will not pass through, for example a primary target. The bullet has been found to be of relatively high accuracy, for example within a four and a half inch group at twenty five metres. Because the bullet is coated with synthetic plastics material, the bore of a weapon from which the bullet is fired is not corrupted by the aluminium alloy which otherwise be the case. In addition, the plastics coating provides a good seal between a cartridge case and the bullet. This is important because of the need to achieve a good gas seal and the need to retain the bullet until the charge in the cartridge has fully ignited. It has been found that a coating of nylon or other plastics material is the best material for this purpose. In order to ensure that the nylon or other plastics material remains in contact with the bullet, thereby avoiding stripping of the coating during pαssαge of the bullet through the barrel of the weapon, it is necessary to ensure that the tenacity of the plastics material to the bullet is high. It is also desirable, ai least in certain uses of the bullet, to ensure that the plastic remains on the bullet in a wound since whilst the bullet can be detected using X-ray techniques, any plastic material which has stripped off the bullet within the wound would not be. In order to ensure good tenacity, the bullet is treated with a chromate conversion coating. According to another aspect of the invention, we provide a cartridge comprising a case containing a propellent and a bullet according to the first aspect of the invention. The invention will now be described in more detail, by way of example, with reference to the accompanying drawing, wherein:- F1GURE I is a longitudinal cross-sectional view through a die block in which a bullet embodying the invention is manufactured; FIGURE 2 is a side elevation of a punch for use with the die block of Figure I ; and FIGURE 3 is a side elevation of a stripper rod for use with the die block of Figure I . There is taken a rod of cylindrical shape made of aluminium alloy of the following composition:- Silicon 0.25% max. Iron 0.40% max. Copper 0.05% max. Manganese 0.05% max. Magnesium 0.05% max. Zinc 0.07% max. Titanium 0.05% max. Incidental Impurities 0.03% max. (each impurity) Aluminium Balance and not less than 99.5% The aluminium alloy is in the H8 condition to BS I 75 and has the following properties:- 3 Density g/cm 2.71 Melting range C _35 Coefficient linear expansion (20 - I00°C) IO '6o C Ik Thermal conductivity W/m°C 230 Thermαl conductivity % IACS 58.4 Electrical resistivity jυ -Λ-ch (20°C) 2.8 Electrical conductivity (20 υ C) % 1ACS 61.6 0.2% Proof Stress * MPa 133 Tensile Strength MPa 146 Elongation on 50mm % 5 Shear Strength MPa 78 Fatigue d -Strength 50 x 10 cycles MPa 45 Hardness Brinell 40 Hardness Vickers 43 Modulus of Elasticity GPa 69 If desired, other aluminium based alloys may be used having properties lying in a range of - 10% of the values set out above. Short cylindrical blanks are sheared from the rod stock and are introduced into a die 10 as shown in Figure I . The diameter of the cylindrical blank is generally such as to be a small clearance with the die to permit of insertion o the blank in the die. "if desired, however, the diameter of the blank may be significantly smaller than the diameter of the die if it is desired to form the blank to increase the diameter to the final desired diameter. The length of the blank is chosen to give the final bullet a desired weight. In the example illustrated the weight of the bullet is 40 grains. In order to form the bullet to the desired weight the die 10 is provided with a radially extending bleed passage 21 and the length of the blank is chosen so that the weight of the blank is slightly greater than the desired final weight of the bullet. In the example illustrated the blank is cut to give a weight of 41 grains. Thus, on forming of the blank with the punch I I as hereinafter to be described, excess material is caused to bleed through the passage 21. The bled off material is stripped from the bullet when the bullet is driven out of the die by the ejector rod 13. The punch 1 1 is then driven into the die to perform a single blow cold heading operation to form the blank to the final desired bullet shape 12. To facilitate removal of the bullet from the die, the rod is coated with a suitable lubricant, such as a drawing lubricant, for example Crown Draw 2710. The bullet is then displaced out of the die by moving the ejector rod 13, shown in Figure 3, to the left from the position, shown in Figure I , which it occupies during the cold heading operation. The resultant bullet has a body 14 having a nose portion 15 of semi-wad cutter configuration having a planar circular leading end surface 16 followed by a frusto-conical side surface 17 which increases in diameter away from the leading end surface. Between the larger diameter end of the frusto-conical side wall portion 17 and a cylindrical side surface 18 of the remainder of the bullet is a planar annular shoulder 19. The trailing end surface of the bullet has a shallow recess of part-hemispherical configuration formed therein as shown at 20. Alternatively, the bullet may be cast to the above described shape by casting into a mould suitably dimensioned to allow for shrinkage on cooling. Thereafter the as cast bullet is sized in a die to the desired final size and the sizing operation removes any casting defects. Alternatively the blank may be mechanically treated, e.g. shot blasted or otherwise mechanically abraded to provide a high tenacity. After removal of the thus formed blank from the die, the formed blank is deburred by tumbling to remove flash and then degreased, for example by dipping in trichloroethyiene. Thus the treated blank is then subjected to a chromate conversion coating operation, such as that known as Alocrom 1200 of ICI Industrial, this is to provide the treated blank with a suitable base for a coating of nylon to ensure that the nylon is bonded to the aluminium with high tenacity. If desired, the blank may be chemically treated in another suitable manner to provide the high tenacity. The nylon is applied in conventional manner using an electrostatic powder coating operation followed by baking. The resultant nylon coating has a thickness of .006 inches. The resultant bullet is then introduced into a generally cylindrical cartridge case which is open at one end to receive the bullet and closed at the other end to provide an enclosure within which the explosive charge is housed. The open mouth of the case is crimped onto the bullet and it has been found that the nylon coating ensures that the bullet is retained within the cartridge case sufficiently long for the explosive charge to ignite fully before the bullet is discharged from the cartridge case. Tests have been performed by shooting cartridges as described above from a pistol into Swedish soap which simulates the effect of a bullet in the human body. It has been found that a bullet embodying the invention produces a wound having approximately eight times the volume of a normal wound. It is thought that the main reason for this is because of the high velocity of the bullet compared with that of a conventional lead bullet. For example, a bullet embodying the invention travels at a speed of approximately 1700 feet per second compared with a speed of 850 - 1 100 feet per second of a conventional lead bullet. It has also been found that the bullet does not exit from the wound which is of advantage where it is desired to use the bullet to immobilise, for example a target in a close quarters situation, where otherwise there is the possibility of a secondary target being wounded by the bullet as it leaves the primary target. Although the invention is primarily concerned with a bullet made of aluminium alloy, particularly an aluminium alloy having a composition falling within the range mentioned hereinbefore, the advantages of high wound volume are thought to be achieved because of the low density of the bullet and accordingly the invention can be made with alloys or other materials, such as plastics material, having relatively low density. In particular, it is considered that a bullet having a density lying in the range of 5 grams per c.c. to 1.5 grams per c.c. will give the main advantages described hereinbefore and in particular, that of high energy transfer on impact which arises from the high velocity and hence low density of the bullet. The bullet may have a calibre lying in the range 0.1 70" to 12.95" and may be fired from a pistol or a rifle. In this specification the composition is expressed in % by weight. The features disclosed in the foregoing description, or the accompany¬ ing drawing, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims: CLAIMS 1. A bullet comprising α body part made of a material having a density lying in the range 5.0 to 1.5 grams per c.c. 2. A bullet according to Claim I wherein the density of the material of the body part lies in the range 2.6 - 2.9 grams per c.c. 3. A bullet according to Claim I or Claim 2 wherein the material of which the body part is made comprises aluminium base alloy. 4. A bullet according to Claim 3 wherein the aluminium base alloy comprises not less than 50-60% aluminium. 5. A bullet according to Claim 6 wherein the aluminium base alloy 10 comprises Silicon 0.25% max. Iron . 0.40% max. Copper 0.05% max. Manganese 0.05% max. 15 Magnesium 0.05% max. Zinc 0.07% max. Titanium 0.05% max. Incidental Impurities 0.03% max. (each impurity) 0 Aluminium Balance and not less than 99.5% 6. A bullet according to any one of Claims I to 5 wherein the body has a coating of synthetic plastics material. 7. A bullet according to Claim 6 wherein the synthetic plastics material comprises nylon or PTFE. " 8. A bullet according to Claim 6 or Claim 7 wherein the plastics material is applied by an electrostatic powder coating operation followed by baking. 9. A bullet according to any one of the preceding claims wherein the bullet has a nose of semi-wad cutter configuration (as herein defined). 10. A bullet according to Claim 9 wherein a shoulder of planar annular shape is provided between the larger diameter end of the frusto-conical side - surface and a following cylindrical side surface of the bullet. 1 1. A bullet according to any one of the preceding claims wherein the bullet is treated with a chromate conversion coating. 12. A bullet made substantially as hereinbefore described with reference to and as shown in the accompanying drawings. 10 13. A cartridge comprising a case containing a propellent and a bullet according to any one of Claims I to 12.

Inventors: JOHNSON PETER IAN, JOHNSON, PETER, IAN
Applicants: JOHNSON PETER IAN, JOHNSON, PETER, IAN
Application year: 1986
Main classification: F42B11
IPC codes: F42B12