Painting question for Brunswick Napoleonics

[Baron von Wreckedoften]

A request to all those who have painted a unit in all-black outfits (needn't be period-specific - could be anything from Ancient Arabs, through Napoleonics, or mid-/late-19th Century, to modern riot squads).

I've just prepped, greenstuffed, and primed (in Halfords dark grey) a load of 28mm Perry Peninsula Brunswickers - about 80 in all.  My question now is how to proceed, given that I want to end up with a "dusty" look -
(a) overspray them all black and start from there, or
(b) do a simple black wash over the dark grey primer, allowing the grey to "come through" to represent fading (but possibly spray officers/NCOs black to replicate finer cloth)?

I'm more inclined to go with (b) for all ranks.  Details of how you did it would be appreciated; photos even more so.

[bandit86]

This was a good tutorial.  To bad she does not seem to post anymore