I don't know what a crud ring looks like, but this thing looked like a spot of spattered candle wax on the wall of the bore.
I was telling the salesman at Bass Pro that I thought my sabot was melting, and he started nodding before I finished talking. He said that this is very common and that treating the barrel with about 30 rounds with swabbing BB in between would do the trick.
I trust y'alls opions, so I figured I would ask y'all too.

Thanks,
Deerplague