40mm:
1 barrel: 1 px thick.
2 barrel or more: 2 px thick.
57 mm:
1 barrel: 1px thick
2 barrel or more: 2px thick
since when? I have never heard, seen or used that rule.
IIRC, 40m and 57 mm both should be one pixel, although there might be some mixing in with the 'water cooled' rules which dictate thicker barrels. 76mm would be the 2 pixel gun.
which 40mm guns have 2 pixel thick barrels?