It probably isn’t even all that dramatacized,

It is not hard at all to do serious damage with a genuinely made sling, there’s a reason people wielding those things operated as a military unit in ancient times, and they were pretty mean spirited folks too!

They’d actually write insults and jokes on the stones like “CATCH ME!”, “HEADS UP!” “OUCH!” “BONK!”

Basically the historical inaccuracies would be in terminology rather than exact action, and also in David not following the shot up with “THINK FAST CHUCKLENUTS!”