When a shotgun cartridge is fired and the shot pellets leave the muzzle of the gun they will remain in flight for the relatively short time that it takes the forces of gravity to bring them back down to the ground. As the pellets fly downrange, they are subject to drop as their velocity slows and the distance to the intended target increases.
This is similar to the trajectory of a rifle bullet – although they tend to have a better shape, retaining velocity better and travelling further for the same amount of drop when fired with the same initial velocity.
Smaller shotgun pellets lose their velocity more quickly than the larger sizes, so their drop (due to gravity) is greater at the same distance – simply because it has taken them longer to get there. This also means that the smaller pellets will travel a shorter distance for the same amount of drop. When fired horizontally, positioned five feet above the ground (average shoulder height), typical number 7.5 pellets fall (five feet) to the ground at 110 yards. By comparison, typical number 9 pellets will drop the same five feet at the shorter distance of 104 yards.
At the shorter ranges, any problem with pellet drop due to gravity tends to be offset by the overall spread of the pellets. If the pellet drop chart is consulted, it is clear that the longer-range shots are most affected by the gravitational pull – gravity has more time in which to exercise its forces upon the pellets. This downward pull is exerted on the entire width of the pattern and along the full length of its string.
Distance and spread
The width of pattern spread at any given distance is an important factor in when it comes to drop. Skeet shooters for example, have no need to worry about pellet drop even when using number 9 lead shot, as at 30 yards, the drop off from the aimed centre bore line is only 1.6 inches low. With a skeet choke at this distance and around 70% of the pellets held within the standard measured 30inch circle, there will be an overall pattern spread of approximately 38 inches. When all of this is considered, a pellet drop of 1.6 inches is not going to matter very much.
Things start to get more interesting as the range increases however, because the effects of pellet drop are much more pronounced. A good example of this other extreme would be a long distance FITASC target at 70 yards, because at this range the number 7.5 pellets will drop by 14inches — virtually half the width of the 30inch pattern circle.This is a much greater pellet drop and it is going to make a real difference at this extended range. In the USA it is not unknown for some shooters to use modified trap guns for FITASC competitions as they are built to place their shot charges about a foot or so high of the aiming point at 40 or 50 yards.
However, although undoubtedly useful at 50-plus yards as a way of keeping the clay target in sight at the moment of firing, this approach does bring its own difficulties at closer ranges where the shot charge will be distinctly high of the aiming point. Pellet drop only becomes an issue at the longest ranges.
George’s long range feat
On a rather interesting side-note, consider George Digweed’s epic long-range clay busting feat that involved a very considerable amount of pellet drop. At the quoted 130 yards range, the front runners in the shot cloud will have dropped by around 6.5 feet from the aiming point, with the slower rearward pellets will have dropping still further. This is even despite Digweed using the larger than usual number 5 pellets