Hi mate i use molly pills on everything and yes it does leave a small amount of black on the target however if you are only mollying for this purpose, give it some thought.
With 6mm pills the slightest mirage and you can't see them anyway, the reason i molly is cleaning i get through the whole day without having to clean and when you are running two guns this is a sensible thing to do
cheers Les
shooting well is more a mental control of your thoughts than just pulling the trigger........