From what I've been told, lump wood charcoal has clay binders too....I'd avoid that, just a mess and silicates can't be good in a bore.
The CIA ( wet mix method ) is simple, but the powder is never as good as a good ball mill can make. Good pure chems and Willow or Alder charcoal, milled for 3-5 hours in a good mill, will make better powder than most commercial consumer grades.
And yes, it's safe to mill dry BP chems. Only a spark or flame can ignite BP, it's not notably pressure, shock or static sensitive and it has a moderately high ignition point, so it's one of the safest "explosives" (if you call it that) to work with. I'd check the old threads on this, we discussed it extensively back in the winter.