Brant Gardner notes that slings were an important part of the Mesoamerican offensive weapon set:
Completing the projectile triad were maguey fiber slings (tematlatl) used to hurl stones at an enemy. The stones thrown by the slings were not casually collected at the battle site but were hand-shaped rounded stones stockpiled in advance, and these also were sent to Tenochtitlan as tribute.
Comparative data indicate that slings have a range in excess of 200 meters (660 feet) with randomly selected stones, exceeding 400 meters (1320 feet) with lead pellets in ancient Greece; slingers in the imperial Roman army could pierce chain mail at 500 paces. As with arrows, standardizing the pellet shape and size increases velocity, distance, and accuracy, and such pellets could be lethal against even armored targets. Diaz del Castillo admired the Indian's use of bows, lances, and swords, but he commented that the sling stones were even more damaging, the hail of stones being so furious that even well-armored Spanish soldiers were wounded. Slings were sufficiently effective that the slinger and the archer were essentially equals; when both were used, they were complementary and usually served close together. (Ross Hassig. Aztec Warfare, p. 80)
[Brant Gardner, Book of Mormon Commentary, [http://www.highfiber.com/~nahualli/LDStopics/Alma/] Alma43.htm, pp. 13-14]
Alma 43:20 [The Lamanites] had only their swords and their cimeters, their bows and their arrows, their stones and their slings ([Illustration]): Weapons and Armor. [John L. Sorenson, Images of Ancient America, p. 130]
Alma 43:20 Their slings ([Illustration]): A figurine of Late Pre-Classic age (the late centuries B.C. to A.D. 300) from west Mexico pictures a man preparing to use his sling to cast a stone. Of course the sling was spun in a circle over the warrior's head before one side of the leather holder was released to allow the projectile to sail toward its mark. [John L. Sorenson, Images of Ancient America, p. 131]