Leadership points

[podcat]

F4U Corsair never used cannons.

Is the italian plane linked a 202 or a 205? 205 had cannon mounted variants

as for Corsairs, there actually was cannon variants:

the F4U-1C was similar to the F4U-1D but its six machine guns were replaced by four 20 millimeter (0.79 in) AN/M2 cannons with 231 rounds of ammunition per gun.[101] The F4U-1C was introduced to combat during 1945, most notably in the Okinawa campaign. Aviators preferred the standard armament of six .50 in (12.7 mm) machine guns since they were already more than powerful enough to destroy most Japanese aircraft, and had more ammunition and a higher rate of fire.[102] The weight of the Hispano cannon and their ammunition affected the flight performance, especially its agility, but the aircraft was found to be especially potent in the ground attack role

http://en.wikipedia.org/wiki/Vought_F4U_Corsair