Spitfire Gunsight adjustment?

[SEE]

Having the cross hairs fixed in IL1946 has been useful in that one learns to estimate distance for a wide variety of ac without reliance on using/adjusting the crosshairs. Fortunately, the gunsight Ring is accurate in CoD (which is the most important thing for me personally) as firing bursts at the precise convergance distance seems to be essential in CoD but when you are closing in at a high rate of knots only a percentage of that burst is focussed.