btw, I have often read that japanese pilots were unhappy with the MG/cannon
(A6M, J2M) firing with different ballistic behaviour, but never heard about
Spit pilots complaints except about the early Hispano jamming and recoil
shake.
Any hints ?

Yann

I am unable to tell exaclty from pictures, but are there seperate
triggers to fire the cannons only, the machine guns only, and both the
cannons and MGs at the same time?

Early spitfires had machine guns only, and had a round button on the
stick. Later on when they went to a mixed machine gun/cannon armament[1]
they fitted a rectangular button. If pressed in the centre it fired both
types of gun, if pressed at the top it fired one sort and if pressed at
the bottom it fired the other (can't remember which way round tho!).

Later on they went cannon-only and I suspose went back to the round
buttons?

[1] That's the 4x 303 and 2x 20mm combination. There where some high
altitude conversions done with 2x .50 and 2x 20mm, and I don't know
what arrangements they had ...
--
These opinions might not even be mine ...
Let alone connected with my employer ...