Yes, of course water will clean black powder fouling and warm water even better. Not all fouling is equal,the residue left from SWISS is a lot less than what is left from Goex or Elefant/ Then again is powder fouling all you are cleaning? How about a mix of powder fouling and your lube? That's why adding dish washing detergent to the water works so well.For a while an equal mix of peroxide, alcohol and Murphy's Oil Soap was popular but the the peroxide had a habit of causing rust although I still see it used in shoots. I've been shooting black powder for 61 years and I'm stilll learning new things.
beagle6