Hello Lefty,

No real training comes to mind, they were used in belt fed machine guns, for us it was the .30 water cooled, .30 light air cooled, and the .50's, either a.p. or ball, there were incendiary rounds as well, aircraft used them 1 in 3 or 4.

I think they were loaded 1 round to 4 rounds ball or a.p., referred to as 1 in 5, or 1 in 4 in some boxes, not much use really, no accuracy to them, they lost weight in flight as they burned, when they hit something solid they would zing off in any direction. Effectively, they also point out the weapon's position in the dark of night, which would draw return fire. Some gunners would pull tracers from the belts, when time permitted, sometimes there was no choice other than grab a can or belt and keep the weapon going. When manning one it's was a good idea to run the thumb of your free had along the heads of each round to ensure none of them had backed out of the belt, those cloth/canvas .30 belts would get loose when they were wet or slimy.

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All the Best
Jack