Thinking of weapons packs - is there any chance of seeing some seperate weapons from Boothill at some point?
On the subject of loose revolvers - Warlord do (or atleast did) a set of WW2 webley revolvers with attatched hands which might be useful (and, whilst the webley is not an authentic period pistol, atleast it's a revolver of some sort

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I've seen a mixed colonial/pulp period weapon sprue on the Irno-Wind metals site, but I can't think of any others off the top of my head (Maybe Blaze-away miniatures, as the old CFM range had some loose weapons)