Well, I guess if I have a choice between blood, sweat or urine, I'll call it blood. What I thought is strange is that the spots where the bluing is missing on the cylinder are on opposite sides and correspond to the patch that is missing on the frame, like there was a glob of something there. The middle photo shows what are almost certainly finger prints. The stories that a 42 year old service revolver could tell... (Maybe nothing more romantic than a fair amount of neglect?)