That is what I have found, rilfes usimg patched balls go back past the middle of the 18th century it would seem that there would be some duplication of useage in the smoothguns, not looking for a if they had it they would have used it mindset just thinking out loud. A thin patch is a quick way to load and keep the ball in place, it seems odd that there would be no usage as many smoothbores as there were from say 1730 on, I suspect at some time some period evidence will arise to validate this practice thou it be the uncommon approach.