I made my first sling around 1965, when I was in the army. Took me a few tries to keep from flinging stones into the ground or directly overhead, but I soon got to the point I could get them going more-or-less in the right direction and achieve very impressive distances.
I joined the "slinging.org" site a few years ago... We have a lot of discussions on all sorts of primitive weapons.
Lately, I have been slinging tennis balls in the back yard for the dogs, who dutifully chase them down and save dad some running...
My accuracy has greatly improved since I adopted the "Apache" style....
My target is the padlock/hasp on my outbuilding and I can hit it a few times out of ten most days from about 50 feet.