GB2343239A

GB2343239A - A training bullet

Info

Publication number: GB2343239A
Application number: GB9823416A
Authority: GB
Inventors: Michael Ernest Saxby
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-10-26
Filing date: 1998-10-26
Publication date: 2000-05-03
Also published as: AU6353799A; WO2000025083A1; GB9823416D0

Abstract

The invention provides a training bullet 2 having a maximum length of 12mm and a minimum length of 9.5mm, the bullet 2 comprising a rounded nose portion 4, a cylindrical mid portion 6 and a cylindrical or tapering tail portion 8, the cylindrical mid portion 6 having at one end thereof a first circumferential flange 10 and at the other end thereof a second circumferential flange 12, each of the first and second circumferential flanges 10, 12 having a maximum axial thickness of 0.1mm and a minimum axial thickness of 0.5mm, the axial distance between the first and second flanges 10, 12 being in the range 3.15mm to 3.25mm, the bullet 2 being formed from a turned metallic material having a specific gravity in the range 2.6 to 2.8.

Description

A TRAINING BULLET This invention relates to a training bullet which is suitable for use with rifles, pistols and machine guns at very low safe energy levels.

There is a recognised need for training ammunition which is light in weight and is non-penetrating but which nevertheless has sufficiently good aerodynamic properties to enable it to be fired accurately.

A major problem with such training ammunition is in obtaining good aerodynamic properties with bullets made from lightweight materials such as plastics. It will be appreciated that a training bullet which is significantly less accurate than the corresponding non-training bullet will be of greatly reduced training value.

A further problem with bullets made from a plastics material is that the barrel can become contaminated with the plastics material and this can lead to loss of accuracy.

It is an object of the present invention to provide a training bullet which is light in weight, has good aerodynamic properties, does not leave contaminating residues in the barrel after firing, and which can accurately simulate the properties of a standard 5.56mm NATO bullet.

Accordingly, in a first embodiment, the invention provides a training bullet having maximum length of 1 2mm, (preferably a maximum of 11. 5mm and more preferably a maximum of 11.3mm), and a minimum length of 9.5mm (preferably a minimum length of 9.75 and more preferably a minimum length of 10.0 mm), the bullet comprising a rounded nose portion, a cylindrical mid portion and a cylindrical or tapering tail portion, the cylindrical mid portion having at one end thereof a first circumferential flange and at the other end thereof a second circumferential flange, each of the first and second circumferential flanges having a maximum axial thickness of 0. 1mm and a minimum axial thickness of 0.5mm, the axial distance between the first and second flanges being in the range 3.15mm to 3.25mm, the bullet being formed from a turned metallic material having a specific gravity in the range 2.6 to 2.8, more preferably approximately 2.7.

The metallic material most preferably is aluminium or an alloy thereof, and in particular aluminium of a grade corresponding to DIN 3.1655.

The tail portion is configured so as to be affixed to a cartridge in a typical taper lock fixing, and hence can either have parallel opposing sides or have a tapering profile. The maximum diameter of the tail portion is typically no more than 5.65mm and the minimum diameter is typically no less than 4.00mm.

The tapering tail portion typically tapers at an angle of from 0 to 10 degrees with respect to the longitudinal axis of the bullet, more usually less than 5 degrees, for example approximately 3 degrees.

The training bullets of the invention are formed by turning on a suitable micro lathe, which can be of known type. A major advantage of turning the bullets rather than casting them is that it enables more or less perfectly concentricity to be achieved, which is highly important to the aerodynamic characteristics of the bullet. In addition, it enables the first and second circumferential flanges (driving bands) to be made sufficiently thin to engage the rifling in the gun barrel correctly, resulting in greater accuracy.

Furthermore, the split lines which inevitably arise when casting, and which contribute to poor aerodynamic properties, are avoided by making the bullets through turning.

An embodiment of the invention will now be described in more detail by reference to the accompanying drawing Figure 1 which is a side elevation of a bullet.

As shown in Figure 1, the bullet 2 has a rounded nose portion 4, a circular cylindrical mid portion 6 and a tapering tail portion 8.

At the two axial ends of the mid portion 6 are circumferential flanges 10 and 12 which function as driving bands for engaging the rifling in a gun barrel. In this embodiment, both driving bands have an axial thickness of 0.05mm, and a diameter of 5.55mm to 5.65mm. The axial distance D between the two driving bands is in the range 3.15 to 3.25mm. The thin axial dimension of the driving bands 10,12 enables them to engage the rifling in the gun barrel more positively thereby ensuring the correct spin rate and minimum barrel dispersion.

The nose portion of the bullet is rounded, the radius at the tip of the nose being of the order of 1.4 to 1.5mm, whereas the curvature of the bullet towards the rear end of the nose portion is of the order of 5.5 to 5.6mm.

The tail portion in this embodiment tapers at an angle of approximately 3 degrees with respect to the axis of the bullet. The shape of the tail portion is such as to enable it to be force fitted (in a taper lock connection) into a cartridge casing (not shown), for example a training cartridge casing. The tail portion is bored out to create a recess 20 which has a cylindrical region of 2.5mm depth at the rear end thereof leading into a conical region of approximately 0.8mm in length, the included angle of the cone being approximately 120 degrees. The recess 20 serves to move the centre of gravity towards the front of the bullet.

The bullet shown in Figure 1 is formed from aluminium DIN 3.1655 grade by turning on a lathe. The resulting bullet has an approximate weight of 7.7 grain 0.2 grain. Bullets of the type shown in Figure 1 are particularly suitable for use with barrel rifling twist rates of 1 turn in 6 inches down to slower twist rates such as 1 turn in 70 inches. The bullets have a stable velocity range of 200 feet per second upwards.

Claims

CLAIMS 1. A training bullet having maximum length of 12mm and a minimum length of 9.5mm, the bullet comprising a rounded nose portion, a cylindrical mid portion and a cylindrical or tapering tail portion, the cylindrical mid portion having at one end thereof a first circumferential flange and at the other end thereof a second circumferential flange, each of the first and second circumferential flanges having a maximum axial thickness of 0.1 mm and a minimum axial thickness of 0.5mm, the axial distance between the first and second flanges being in the range 3.15mm to 3.25mm, the bullet being formed from a turned metallic material having a specific gravity in the range 2.6 to

2.8.
2. A training bullet according to claim 1 having a maximum length of

11. 5mm.
3. A training bullet according to claim 2 having a maximum length of 1 1. 3mm.
4. A training bullet according to any one of the preceding claims having a minimum length of 9.75mm.
5. A training bullet according to claim 4 having a minimum length of 10. 0 mm.
6. A training bullet according to any one of the preceding claims wherein the metallic material has a specific gravity of approximately 2.
7 7. A training bullet according to claim 6 wherein the metallic material is aluminium.
8. A training bullet according to any one of the preceding claims wherein the tapering tail portion tapers at an angle of from 0 to 10 degrees with respect to the longitudinal axis of the bullet.
9. A training bullet according to claim 8 wherein the angle of taper is less than 5 degrees.
10. A training bullet according to claim 9 wherein the angle of taper is approximately 3 degrees.
11. A training bullet substantially as described herein with reference to the accompanying drawing.
12. A round of ammunition comprising a cartridge casing having affixed into a forward end thereof a training bullet as described in any one of the preceding claims.