Field Target - Physics and Technique

Physics and Technique

Pellets from a .177 inch rifle running near the UK legal limit of 16.27 joules (12 ft.lbf) will drop around 11 cm over 55 yards (50 m) – more than enough to miss the kill of a target completely – so it becomes necessary to compensate for range by adjusting the elevation of the barrel. Two common methods used are: moving the crosshairs above the center of the target by a lesser or greater degree (hold-over), often using markings on the reticle of the scope for reference, or adjusting a knob (turret) on the scope to drop the crosshairs onto the point of impact for a given range such that the pellet appears to go exactly where you point the gun (windage excepted). Competitors will often carry a small printed table of different ranges with their appropriate drop compensation or calibrate their elevation knob (often using an enlarged knob) – combined with the range-finding ability of the scopes, this allows for very accurate vertical placement of the pellets.

Wind presents probably the largest challenge for an FT shooter – while it is not too difficult to hit even the furthest targets on a perfectly still day with a little practice, mastering shooting in wind can take many years. Pellets can be blown sideways by even a light breeze. At longer distances this can start to cause misses, as the pellet will often be blown onto the faceplate if you aim centrally. In stronger winds it is not uncommon to have to aim completely off the faceplate in order to score a hit, and judging the amount of compensation to apply takes a lot of practice and experience. Head and tail winds can also have an effect on the trajectory of the pellets, causing them to hit high or low. It is common to fit a “windicator” to the barrel of the rifle – a piece of light cord with a feather on the end will provide a good indicator of general direction in light winds when it may not be entirely obvious, but it does not tell you what the wind will be doing on the way to the target. Competitors may choose to lift the reset cord of a target off the ground to get a feel for this wind – it will arc gently in a steady crosswind, and may even reveal changes in wind direction caused by nearby trees and foliage. Although many scopes have mechanical adjustment for horizontal offset, it is primarily used to ensure the rifle is shooting straight ahead in still conditions. The variable nature of the wind means it is often easier to aim off target (sometimes called “Kentucky windage” in the US) than to try to adjust the calibration of the crosshairs.

One measure of the difficulty of a field target shot is the Troyer (named after Brad Troyer). At its simpliest, a Troyer is the distance to the target in yards divided by the kill zone diameter in inches. (Obviously, this can be adjusted to meters/mm by multiplying by 2.32.) Thus, if a target is at 45yds and the kill zone is 2in, the difficulty is 45/2 or 22.5T. In practice, there are additional multipliers for various conditions such as targets over 45 yards, wind, "extremely" dark/light conditions, standing/kneeling positions, and uphill/downhill shots. A typical course would have a difficulty averaging about 25T with a spread of difficulties from as low as 10T to perhaps as high as 60T. A well-designed course can be used for all field target classes although the PCP shooters will typically outscore the piston shooters. When one is practicing for a match, a good approach is to shoot at targets (whether paper or actual field targets) with a difficulty of about 20T to start. As one gets better, the difficulty is increased (either by increasing the distance or reducing the size of the kill zone) -- a good rule-of-thumb would be to increase the difficulty by 5T when one can successfully hit the target 90% of the time. Eventually, one should practice at about 45T if they expect to be competitive at local matches and 60T for national matches.