After one range day of shooting spit patches this last year, I think I agree with your theory Keb. Out hunting I never really noticed a difference, but hunting, I'm only shooting a few rounds at most. (which is most of my limited experience) It was at the range that I really noticed the difference. If I remember correctly, someone here at the TMA stated that BP residue, after firing, actually has an oily base. I noticed it when I first started shooting BP, but thought the oily residue was from my pre-lubed patches. I might be switching to buying only dry patches in the future.