A little off topic, but can anyone tell me why two .303 machine guns were used as "aiming" devices/strafing weapons on the Hurricane Mk. IID and the Mk. IV's universal wing? I can understand the argument that Britain had an excess of .303 machine guns for craft, but wouldn't a larger round be more conducive to helping the aim of rockets, bombs, and 40mm guns? To me at least, it would seem like the lighter .303 round might not be very predictive of the path of the heavier weapons. I understand that there were sights and markings on the Hurricane's to help with aiming, but I know I've read about pilots somehow (can't remember the exact method) using the 2 machine guns to line up their target before firing the heavy weaponry.
Note: If I sound redundant in any of my questions, its because its a test day and I'm working on exactly 0 hours of sleep (mind was too active the night before with math equations).