This section of the link offered by Mike38 poses a question related my previously described experience:
"Our customers have fired thousands of rounds through various guns without ever cleaning the bore, or needing to. When you use our bullets and the right load combination, you'll be surprised at how clean the bore stays. Run a dry patch or two through it after use and you might never need to do anything else. You can brush the bore with a brass brush, but this is usually unnecessary."
If I run a dry patch through any of my guns after firing, the patch will be black to some degree, due to carbon from powder burn. If this coating is moly, that, too, imparts a black coating on the patch. That one "might never need to do anything else" raises the question of what might one need to do? And what is expected of the use of a brass brush?
"For these reasons, one of the biggest advantages of using BCS bullets is cleanliness. Clean to handle, clean to load, clean to use. The small amount of black you get on your fingers is harmless, and this molybdenum-disulfide washes off easily and is a good reminder that using BCS bullets will keep everything else clean."
This is exactly what I experienced with my moly'd bullets - it washed off easily from my fingers, but I could never wash it off the barrel bore, and over time, I think it accumulated to adversely affect the accuracy.