Got a Real-World Weapon, Armour or Tactics Question? Mk. XXX

[Gnoman]

Plenty of records of the Spanish dealing with deaths at long range (up to 400 meters)from Aztec slings let alone point blank blows and the Romans has special tools for removing sling shot from the wounded.

Don't extrapolate too much from this. The Spanish abandoned a lot of their armor because the environment they were in was so hot and humid. This is well documented. There's also a lot of second-order reports from people who weren't there making assumptions on what happened that have been heavily conflated with the eyewitness reports. Not to mention, of course, that the vast bulk of the forces used by Spain against the Aztecs were locals - the relatively small number of Spaniards allied with many of the Aztec's long-term enemies, who never had late-era steel armor in the first place.

That the Spanish took casualties from slings is almost certainly true. That doesn't mean that the slings punched through armor meant to stop musket and pistol fire. There's a good chance that the casualties in question were unarmored entirely.

If slings could punch through a 16th century breastplate at all, no difficulty in learning the weapon would have stopped ancient empires from imposing sling training by force. Because if a Spanish breastplate won't stop it, absolutely nothing will. Guns probably would never have been adopted at all.