I hunted big game with them as a kid growing up on the ranch. Whittled out of a crotch branch with inner tube power bands and piece of heavy leather for the pouch all tied off with sinew. BTW, the big game was usually grasshoppers, stink bugs, pine squirrels, snakes and an occasional lizard, rabbit or bird. Never had a store bought slingshot. When I got older I made and used slings instead and really got quite good with them. A lot more powerful than any slingshot and capable of some pretty impressive results. Never got pushed into trying them on a "Goliath", but killed quite a lot of small game, upland birds and waterfowl with them up through my teens.
Made slings again when my son got tired of his store bought slingshots and showed interest in them. But we only used them for entertainment on camping trips and outings. Pine cones out of the tallest trees was a favored target, as was anything in the middle of a lake, pond or floating down a river.