Interesting....
I wish you had mentioned this in your original reply.... Totally different animal, a pipe versus a water bottle,,,,, and a different but interesting subject. I'd certainly like to know more, but it is a subject for another topic thread.
It also would have tempered your very "irrefutable" sounding answer.
After I cast round balls, I put them in a plastic bottle and let it bounce around int the bed of the truck for a 30 miles or so. I wonder if the same approach could be used for gourd cleaning.
It's funny you posted this now, I've never been to a rendezvous or any living history event, but I'm curious and thinking about trying it on for size. I was just googling last week how to make a gourd canteen because I figured I'd need water if I do.