I did a search to make sure this wasn't posted before, so, if it was, my apologies. Ray Mears did a series about the U.S. two years and lo and behold a sling pops up. His technique needs some practice and it's funny to see that he tied a second finger loop to shorten the sling. It looks to be made out of genuine Braintan. The segment of the slinging starts at 31:46, but the background story starts at 29:46.
https://www.youtube.com/watch?v=7goxZ6ihdzU

Great sling, very accurate to ones I have seen in US museum collections online. The diamond holes make the pouch fold easily across the widest point. The cords have a slit cut in their end and loop through the pouch and back through themselves.

Prerty cool

Why does he keep referring to a sling as a slingshot?  Is that British terminology, such as some of the older people around where I live referring to a slingshot as a "flip"?

because he doesn't really know anything about slings.
Pretty much everyone seesm to start out calling them slingshots - until you correct them :-)

The chap with him was clearly not convinced lol
It does seem unlikely that at that stage slings were still used.
Shame really, they could have done some real damage with slings and grenades.

Nothing British about calling it a slingshot I'm afraid... too many people on this side of the pond call it a slingshot as well.
I'm happy to correct them. 8-)