I have harvested rabbits and squirrels with my hunting slingshot (I have small backpack model, a mid-sized folder, and a big extended-fork hunting model)
Pardon my doubting ways. There is no better evidence than meat in the pot.
I assume you are using steel shot and not pebbles out of the local streambed?
I do carry about 12 - 6mm steel balls with me, weighing in at about 1 1/2 ounce. One of the gifts of the glaciers here in MN is the deep and common deposits of smooth gravel. Appropriately sized round-ish pebbles can be surprisingly accurate due to the 'golf ball effect'.
Don't get me wrong, I'm not advocating that anyone depend on a slingshot as their primary survival tool. I am a big fan of the .22 and if I'm not carrying a shotgun, that's what I usually have with me. That said, there are places and times, such as big state parks and public hiking trails, where any firearm would be problematic, so I have my slingshot.
The little one weighs only 4 oz, and the balls weigh 1 oz for 8. If a person is gram-conscious, they could just carry a replacement power band and a couple of rubber bands to make a slingshot from a tree branch with the knife and saw on their Wave.
Some past postings here recount an incident where coyotes got bold along a public hiking trail, and killed a female hiker. If she had been able to deploy a slingshot with a marble-sized pebble at 10 yards, that coyote would have run howling into the woods.
All this rationalization aside, my wife has diagnosed that I never really grew up all the way. My latest quarry was ice formations along a partially frozen creek in the backwoods last weekend.