But sometimes the shot cloud looked grey, and at other times bright silver. Why?

Mike George
I noticed this, too, and believe the silvery effect was due to the fact that the majority of shooters, particularly in the trap disciplines, were using nickel-plated shot.

As to why, some shooters will tell you that nickel-plating makes shot harder.

It doesn?t, but it does give the surface of each pellet a more slippery, lubricated film.

This helps prevent shot becoming oval, particularly when forced through the tight chokes preferred by trap shooters, and therefore give better patterns.