hi tricocloud
you could be right, but it's a bit late in the day to be sure, the Bible is probably as vague/wrong about the type of sling as it is about various other things.
the thing is, in remote parts of the world shepherds still use slings as they have done for 1000s of years and as far as i know, these are all variations on the usual sling - not staff slings.
since david was a shepherd before he discovered his military and political genius, it's safe to assume that he was an adept with the sling which is still favored by today's shepherds, for it's lightness (less hassle to carry) and ability to work with small stones at low power. staff slings were, according to records, military weapons of some size with a typical large projectile - it's one thing to dissuade a sheep from straying, another to crush it's skull like an eggshell
you might be right, but on balance it's more likely that since D was a shepherd he used a shepherd's sling (like shepherds still use) and not a staff sling (which they don't)
welcome to the forum
SV