I have a bit of experience slinging. My thought is that the shape allows for the projectile to leave the sling pocket in a fairly repeatable orientation thus eliminating one of the many variables that affect accuracy. Achieving accuracy when throwing, slinging, shooting, hurling, tossing, or chucking is a matter of practice and eliminating variables, i.e. grip, distance, sight alignment, breathing, consistent projectile weight, shape, powder charge, warhead weight, number of windups, etc. Quarterbacks throw the football only one way so the toss is predictable. Pitchers throw unpredictably with myriad variables to confuse.
Check out this guy slinging:
https://youtu.be/RzDMCVdPwnE
Interesting video ... pasty-skinned dude needs to spend some time in the sun.
Of course accuracy would improve with practice but I would hope that the slingers had a backup weapon like a sword because unless you were very close, it would very likely only stun a target. You or someone with you would need to take that moment to incapacitate the target.
When I was young I played with slingshots, both the ‘Y’ shape and the kind in the video. I learned the bible story of David and Goliath and was surprised that David slew Goliath with the rock and sling. It was not until I was older that I learned that David terminated Goliath by removing the head, not because of the sling shot.
That was a fantastic video! You can make a sling from tree bark and other plants in a day with knowledge in finding, plaiting, and knotting their fibers. The slinger never used the almond-bullet (that I could see) and just whatever spheroid stone was at hand. He was aiming for an approximately 12”x12” target through most of the video. He rarely hit but came close a lot. Were he slinging rocks at a formed body or large animal, he’d hit most every time. I imagine professional/cultural slingers from antiquity with their formed bullets and constant practice could hit the small targets enough to have rabbit or squirrel stew whenever they liked!
Love that website. Watched all the ones on building hut and tools.