Editing the Current Data for the Quarry, Accuracy and other parameters

To change the quarry type, use the I (Input) and then Q (Quarry) keys to bring up the Quarry Selection panel. As previously, use the & keys to select, and press the (enter) key to load the relevant data. To view the characteristic of the quarry, at the Current Data panel, press Q (Quarry): an explanation of the data then shown can be found in the Part 2 of this manual.

The 'Probable X-speed' (crossing speed) and 'Maximum Entry Energy' can both be edited in the Current Data panel.

The crossing speed refers to the speed at which the quarry crosses the shooter's field of view: this affects both the amount of forward allowance required, and may cause a reduction in accuracy. The maximum crossing speed usually equals the typical flying speed of the quarry: a typical flying speed of 15m/s is roughly 34 miles-per-hour. Going-away shots clearly have lower crossing speeds, as do birds flying into strong headwinds. Note that whatever value of crossing speed is specified, it remains the same for all computed ranges. In practice, however, it is likely that the field skills (decoying etc.) which contrive shorter ranges may also promote much lower crossing speeds, and so when computing for shortened ranges then do adjust the crossing speed to suit.

The 'Maximum Entry Energy' refers to the typical kinetic energy per square millimetre required for a pellet to penetrate past the thickest layers of feathers and skin. For wildfowl the thickest layer is usually on the breast, and the required 'kinetic energy density' will vary between species… and indeed will vary both from bird to bird and through the season. Other areas of the bird are less well 'protected', and this is accounted for by the quarry datafile.

Note that the predicted Hit Rate changes when the Maximum Entry Energy is changed: this is because the program only counts pellets as effective 'Hits' if they penetrate, rather than being stopped by the feathers and skin.

The section of the Current Data panel on Accuracy quantifies the accuracy of the shooter.

The four contributory parameters are

	Basic error …	the basic shouldering and pointing of the gun,
	Swing error	because target movement undermines the accuracy,
	Lead error	due to incorrect judgement of how far ahead to shoot,
and	Range error	arising from estimation of range.

The shooter is generally not aware of these contributions, but with increasing experience and skill will probably improve each of the four parameters. For just one shooter, the detailed testing required to quantify these parameters is rather complicated, so the program datafiles include representative data for shooters of varying skill. For the worked example the shooter accuracy datafile was 'Accuracy versus gamebird: Very good'. The datafiles include data for 'Poor' shots (i.e. a beginner) up to 'super'. Press I (Input) then A (Accuracy) for a reminder of the available datafiles. You will see that the artificial environment of clay pigeon ranges requires separate datafiles. For example, a competent duck shooter is also likely to be a good clay shot, so both 'Accuracy versus clay: Good' and 'Accuracy versus bird: Good' datafiles reasonably apply to the same shooter -select the datafile according to the target. 'Super' accuracy is used to describe the most accurate shooters. The inclusion of the 'Perfect' accuracy datafile allows for assessment of experimental work where the shotgun is placed in a solid mount and fired at centralised test targets.

To check whether the Accuracy datafile you select for yourself is reasonable, see whether the hit rate predicted for standard clay pigeon is roughly comparable with your achievement on the clay range … keeping in mind that this program is not a precision tool for assessing performance against clay pigeon.

The only remaining Current Data aspect not discussed so far is the Drag Factor.

The aerodynamic data used by the program assumes that the pellets are smoothly spherical. However, the pellets may be deformed or rough, so the Drag Factor has been introduced to account for the effect this may have on the pellet flight. For perfect pellets the Drag Factor value is 1.000, but for misshapen pellets the aerodynamic drag is greater, so the Drag Factor is increased to, say, 1.100. Some surface finishes may actually reduce drag (as is achieved by the dimpling of golf balls), so the Drag Factor may vary between 0.9 and 1.15.

It is only possible to estimate the true Drag Factor by comparing the predicted down-range velocity with that measured or sometimes declared by the manufacturer. To do this, in the Current data panel edit the Drag Factor and then examine the predicted velocities listed by pressing T (Table). If in doubt, use a Drag Factor value of 1.000.