F6F .50 cal. Loadout

Tracers have a red tip, AP have a black tip. Not sure about API (armor piercing incendiary). The ratio of round types depends upon the armorers/ordnance handlers. Those are the guys who link up the ammo. I have read of some pilots who did not like to use tracers at all in order to not spook their target in case they missed with the first burst. Others may want a particular ratio of say 3 Ball, 1 Tracer, 1 AP or API. 

stikpusher

Tracers have a red tip, AP have a black tip. Not sure about API (armor piercing incendiary). The ratio of round types depends upon the armorers/ordnance handlers. Those are the guys who link up the ammo. I have read of some pilots who did not like to use tracers at all in order to not spook their target in case they missed with the first burst. Others may want a particular ratio of say 3 Ball, 1 Tracer, 1 AP or API. 

I remember a family friend who'd served as an armorer on flattops saying that they always liked to have API (silver tip) in the mix, since Japanese planes on the whole were so prone to catching fire. But alot of the particular mix of rounds was down to the pilot; as Stik said, some (almost certainly the better marksmen) didn't like tracers, to keep the element of surprise.

BTW, the Wikipedia entry for the .50 cal BMG has a list of rounds and indicator colors here.

Thanks Gentlemen, that's what I was looking for.