Did David Use A Stone?

During my research into 18th century small bar lead, I came across some interesting info on slings and their ammunition. It seems that David may not have picked up a stone to slay Goliath, he may in fact have used one of three sizes of lead bullets.
There were three types of lead bullets made for slings, one for killing, another to break shields, and yet another to smash the timber boarding on ships. All of these were wielded in the common sling of that time.

http://www.historyofinformation.com/expanded.php?id=2485;

http://www.ancientresource.com/lots/roman/weapons-sling-bolts.html;