GB2223833A

GB2223833A - Bullet trap

Info

Publication number: GB2223833A
Application number: GB8912576A
Authority: GB
Inventors: Norman Clifford Smith
Original assignee: Galt Composites Ltd
Current assignee: Galt Composites Ltd
Priority date: 1988-06-02
Filing date: 1989-06-01
Publication date: 1990-04-18
Also published as: GB8813065D0; GB8912576D0

Abstract

A bullet trap has a head 14 and a shaft 12 which retains a penetrable wall in a chamber which lies in front of a conical stop wall 50. The penetrable wall comprises progressively harder layers 44, 46, 48 of aluminium, glass reinforced polyester and ceramic. The chamber has an entrance passage of lesser diameter than the chamber. <IMAGE>

Description

BULLET TRAP The invention relates to a bullet trap (a projectile).

It is known to construct such a projectile by connecting a hollow shaft to a solid bulbous head. The shaft is fitted onto the end of a rifle barrel, or onto an extension thereof such as a flash tube. Until now, either blanks or special rounds had to be used to avoid the risk that the solid heads which are currently used for bullet traps could cause an uncontrolled destruction of a normal bullet on impact with the head, resulting in some material rebounding in the direction of the firer.

In an attempt to overcome this problem there is provided, according to a first aspect of the present invention, a bullet trap having a penetrable wall which lies in a chamber in the path of the bullet in front of a stop wall. The penetrable wall performs both a retarding and distorting function on the bullet, and assists in a controlled transfer of momentum to the projectile and in preventing escape of its material.

Preferably, to give greater control, the penetrable wall will be made up of a number of layers of materials of different characteristics; the laminate will preferably contain one or more layers of material which will cause the jacket of the bullet to be stripped from the case as the bullet penetrates through them.

Normally the layers will be of progressively increasing hardness in the direction of travel of the bullet; a three-layer structure may include a first metallic (e.g. Al Alloy), a second GRP armour and a third ceramic (e.g. fused alumina) layer.

Preferably the chamber will have a front wall (i.e. in the direction from which the bullet enters) which surrounds a shaft passage of a diameter less than that of the chamber.

An embodiment of the invention will now be described by way of example and with reference to the sole figure, which shows a diametrical cross-section through a bullet trap.

A bullet trap 10 has a cylindrical shaft 12 which extends between a bulbous cylindrical head 14 at its front end and a stabiliser assembly 16 at its rear end. The stabiliser assembly 16 comprises six axially extending fins 18 which project radially outward from points spaced regularly about the circumference of the shaft 12. Each fin 18 extends perpendicularly from a curved base plate 20 which rests against the cylindrical outer surface of the shaft 12. The base plates 20 extend beyond the fins 18 in both forward and rearward directions, and the assembly 16 is retained in place upon the surface of the shaft by two collars 22,24 which ring each of the forward and rearwardly extending parts of the base plates 20 respectively. Two fins 18, situated diametrically opposite to each other, are provided with holes 21 to enable a line to be attached to the bullet trap.Of course other materials and means for providing stabilising fins, e.g. an integral moulding with the shaft, or use of hard plastics or rubber materials can be adopted.

The shaft 12 is made of aluminium alloy (e.g.

HE30TF) and is hollow, having a through passage with cylindrical front, centre and rear chambers. The centre chamber 30 has a smaller diameter than the rear chamber 32 and the two chambers 30 and 32 communicate with each other via a frusto-conical portion 34. The front chamber 28 has a larger diameter than centre chamber 30, but a smaller diameter than rear chamber 32, and extends from the centre chamber 30 to the front end 36 of the shaft 12. The front end 36 of the shaft 12 is stepped and has a smaller external radius than the main body. This feature enables easy engagement of the head 14 with the shaft 12.

The head 14 has an aperture at its rear end, into which the stepped front end 36 of the shaft projects.

Screws 38 extend radially inward from the surface of the head 14, and project into the stepped front end of the shaft 12 to secure the head 14 and shaft 12 together. The front end of the head 14 is semi-spherical. However, the head may be part of a larger entity such as a gas canister or an anti-personnel grenade, or may be adapted to fit into such an entity.

The head 14 is partially hollow, having a cylindrical passage 40. When the head 14 and shaft 12 are connected, passage 40 communicates with the passage through the shaft 12; passage 40 has a larger diameter than the cchamber 28 in the shaft passage. The passage 40 is partially filled with a penetrable wall made up of three disc-shaped layers 44,46 and 48, which are retained in it by the nose of the hollow shaft 12. More specifically the wall comprises layers of progressively increasing hardness: an aluminium alloy (NS8) disc 44, 4mm thick at the rear (i.e. first impact) end of passage 40; a disc of "Galt Glass Armour" (a glass reinforced polyester material) 46, 12mm thick adjacent disc 44; and a ceramic (A102) disc 48 at the front end of passage 40. Passage 40 has a conical front wall 50 to act as a stop wall.

In operation, the bullet trap 10 is placed over the open end of the barrel or flash suppressor of a rifle so that the barrel projects into the rear shaft chamber 32.

When the rifle is fired, a bullet leaves the barrel and passes through frusto-conical passage 34, centre and front shaft chambers 30 and 28, whereupon it comes into contact with aluminium alloy disc 44. The bullet's momentum causes it to penetrate through aluminium alloy disc 44.

During penetration through disc 44 the bullet's jacket (e.g. copper, steel) is stripped from its lead/steel core.

This process is completed when the bullet penetrates through Galt Glass disc 46, so that by the time the bullet reaches ceramic disc 48 it is a ballistic core. This core is distorted by and distorts the ceramic disc 48, and may distort material of the disc into the conical stop wall 50 transferring all of its momentum to the bullet trap 10.

In this arrangement, back-scatter is largely prevented because the three discs 42, 44 and 46, are not sufficiently unyielding to cause the bullet to rebound.

Any material rebounding will find itself trapped in the chamber 28 by the face 29 at its step transition to central chamber 30.

Control of the energy-transfer characteristics can be achieved by the choice of materials in the respective layers and by the shape and volume of any gap chamber in front of the final portion of the penetrable wall, into which in the last stage of the trapping of the bullet material of the wall and/or of the bullet will be forced.

Claims

1. A bullet trap having a stop wall and a penetrable wall which lies in a chamber in the path of a bullet in front of the stop wall.

2. A bullet trap according to Claim 1 where the penetrable wall has at least two layers of material which are of respectively different hardness characteristics.

3. A bullet trap according to Claim 2 therein the penetrable wall is at least two layers of material which are of hardnesses progressively increasing in the direction of travel of the bullet along the path.

4. A bullet trap according to Claim 2 or Claim 3 wherein the penetrable wall has three layers.

5. A bullet trap according to Claim 4 wherein the three layers are, in order of increasing hardness, of metal, of GRP and of ceramic.

6. A bullet trap according to Claim 5 wherein the metal is an aluminium alloy.

7. A bullet trap according to Claim 5 or Claim 6 wherein the ceramic is an alumina ceramic.

8. A bullet trap according to any one of preceding claims wherein the chamber has an entrance passage of a diameter less than that of the chamber.

9. A bullet trap according to any one of the preceding claims wherein the stop wall is of conical shape with its apex directed away from the penetrable wall whereby a conical-ended chamber is formed between the penetrable wall and the stop wall.

10. A bullet trap according to any one of the preceding claims wherein the bullet trap comprises a head and a discrete hollow stem fitted to it, the penetrable wall being provided by one or more discs of material retained in the chamber by the stem.

11. A bullet trap substantially as herein described with reference to and as illustrated in the accompanying drawings.