Is it just me or does it bother anyone else that a sling is continuously called a "slingshot"

[David Davidson]

In the game Jack's sling is always called his slingshot, however a slingshot uses elastic potential energy (much like a bow does) rather than stored kinetic energy by spinning a stone around in a pouch then releasing it at the right moment sending a stone in the direction of a target.
Elastic and rubber was only discovered with the new world so a slingshot would be an impossible invention historically.
It always annoys me when everything else fits the century (almost) but a simple sling is called a slingshot throughout all 3 books. The original book was written in the 80s a mistake like that would be noticed less, however personally I'm an okay shot with a slingshot but if I used a sling the stone/metal ball could go anywhere as letting go of it at the exact right time is about as hard as precision archery with an English (Welsh) longbow.

It's like calling an atlatl (a wooden spear throwing device that gives mechanical advantage but doesn't store energy) or a throwing string (basically a string which gives more mechanical advantage to the spear and used infrequently in European medieval times) a longbow to me because both put pointy things down range.