Some vids detailing historical use of slings. Again, in most version of D&D, this is a Simple Weapon that anyone can use. Halflings usually get some nice bonuses with slings, and some editions of D&D go absolutely bonkers with halfling-only sling feats that produce some damage potential to easily compete with longbows and crossbows. (I can't find the character sheet, but I had a 4e halfling ranger/rogue who, in natural terrain, take 5 foot step at the start of her turn, then use her sling to cause 5d6+4 damage. That was awesome.)
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