Abstract
A number of commonly used and available 12 bore shotgun cartridges were fired at paper targets for the purpose of evaluating their lead shot pattern density and uniformity. These results are compared to published literature to establish which factors are most important in influencing the nature of the shot pattern and limiting its effective range. Other ballistic considerations, including pellet energy, are then reviewed to see if there are any recurring trends which might suggest the types of cartridges best suited to shooting a variety of South African game bird species.
Introduction
The performance of a shotgun may be defined by three important factors, namely pattern density, pattern uniformity and pellet energy. It is well documented that not all shotguns produce the same pattern with the same shot charge or pellet size, since a number of variables inherent in the manufacture of the gun and the cartridge influence the shot pattern. These variables include the forcing cones in the barrel, the diameter of the barrel and how the barrel is choked. The barrel then interacts with the fired shot load to further influence the pattern produced. As regards the cartridge: shot size, shot mass and hardness, shot consistency, velocity, type of wad (traditional fibre or the more modern plastic cup) and the burn rate of the powder all potentially influence the pattern. Given the number of interactive variables, all of which potentially affect performance, it is important to identify the specific purpose for which a cartridge is to be used and to then test a variety of cartridges in order to find one which best suits the objective.
It should be recognised that shot patterning tests are not a true reflection of the potential of a particular load under all circumstances. The pattern, as it appears on a flat target surface placed at right angles to the path of travel of the shot charge, represents a ‘frozen’ two dimensional (vertical and horizontal) representation of the pattern. On the target, it appears that the pellets have arrived at their destination as a ‘wall’ and all at the same time (Illustration 1).
In reality, however, the pattern comprises a third (longitudinal) dimension resembling a ‘cloud’ of pellets, some of which arrive at a target later than others (Illustration 2) rather than all simultaneously in a ‘wall’. This phenomenon of a pattern is referred to as ‘shot stringing’. The consequence of shot stringing is that any consideration regarding the effectiveness of a shot pattern derived from a two-dimensional representation is unrealistic, as this method of testing cannot reflect the delayed striking of some pellets on target. Therefore, such a representation is only an indication of the best that the pattern can ever be.
For bird shooting, it is the cumulative effect of the striking energy and the penetration of pellets in a pattern that ultimately determines their effectiveness or lethality. The nature of the pattern is the result of many factors, including pattern density, pattern uniformity and the stringing of a shot charge as well as pellet size and velocity. Here, pattern uniformity is of particular significance, since the more uniform the distribution of pellets, the greater the likelihood of achieving a desired number of pellets on target and, particularly in the case of live quarry, within a vital area. Likewise, shot stringing must be considered, as this affects the time it takes for some of the pellets to reach a moving target. Unless the pellets maintain sufficient energy to effectively penetrate, the bird will not be killed efficiently.
Regardless of the potential implications of shot stringing and pellet energy, these are taken into account by reviewing and making reference to published information. Although, in this study, no tests were undertaken.
Please note: Under no circumstances is it suggested that my findings constitute any form of definitive research on this subject. On the contrary, sample sizes are far too small, and in the light of the limited use of random sampling,
