jaybe
Everything you say is correct - my point, if there is a point, is the use of flammable materials in the barrel of a ML containing residue should be approached very carefully. It does not happen often but it could. Muting the IPA with water/windex will certainly help alleviate the problem. The water/windex will slow and raise the flash point of IPA.

Using pur IPA to clean oil from a barrel prior to shooting - can not imagine that being a problem. Using pure IPA between shots I think you a raising the level of probabilities there.