[Metatron]

You need to enable the sight by assigning a key to this function. There are three modes you can cycle through, a)plain gunsight, b)gunsight and gyro and c)gyro only.
You then have to assign a key for 'decrease sight' distance and one for 'increase sight distance''. You then adjust the sight so that it corresponds to the enemy aircrafts wingspan. You can also cycle through various axis aircraft wingspans with the arrow keys.
Then you put the dot on the enemy and track him for a second. The sight calculates the lead required, and you shoot him.

Check the picture I posted in the 'Askania photos and information' thread.