Large arrows are the original type of ammunition used for torsion artillery. The weapon type was originally intended as a way to store more than a single human's draw strength in a bow; the earliest form of "artillery" is the gastraphetes or belly bow, which can be drawn with two hands. In other words, artillery was invented as a more powerful way to shoot arrows, not as a way to hurl stones. With the development of torsion artillery, such arrows could become larger and heavier, taking the form of solid metal bolts, which could be fired at ships, battlements, or army formations.

It was only after the appearance of these giant bolt-shooters that the Greeks began to find ways to project round balls as well. The two types of ammunition remained in use throughout antiquity and into the Middle Ages, with neither ever replacing the other. It's only in the modern imagination that catapults and trebuchets form the full range of Medieval artillery. Indeed, the earliest depiction of a cannon in Medieval Europe depicts it firing a pointed, arrow-like projectile, suggesting that it was not immediately obvious that cannon were most effective when firing balls.