sling bullets

[D B Campbell]

in what shapes could you get lead sling bullets? are they always oval in length and round in width?

Völlig* has diagnosed six forms, one with three variants and one with two variants (= 9 in total), but the majority are basically "oval in length and round in width", as you said. Völlig's Typ I ("ovoid") is basically the classic lemon-shaped bullet; his Typ II ("bikonoid") is very similar; his Typ III ("doppelpyramidenförmig") is more angular, but is known from only four sites; his Typ IV, a more rounded version of III, is known from only three sites; his Typ V ("eichelförmig") is the well-known acorn shape, known only from Birrens, Burnswark and surroundings; and his Typ VI are the spheroids from Gellep.

or could they be for example oval in length and square in width?

This sounds a little like Völlig's Typ III (5 examples from Asculum, 1 from Volubilis, 1 from Utrera, 1 from Ursao), pointed at each end, but square cross-section in the middle.

* Th. Völlig, "Funditores im römischen Heer", Saalburg-Jahrbuch 45 (1990), pp. 24-58.