Price varies: light 806 gp; standard 1,966 gp; heavy 4,006 gp; Slot none; CL varies; Weight 1/2 lb.; Aura moderate or strong transmutation
A boulder bullet appears to be a magical sling bullet when held, but it is actually a shrunken piece of catapult ammunition.
A boulder bullet expands rapidly when launched from a sling or sling staff, increasing in size and dealing greater base damage depending on the version used. This doesn’t affect the bullet’s range or any of the normal mechanics for using a sling bullet, though the boulder bullet is treated as siege weapon ammunition for the purposes of wind effects and similar penalties. Similarly, if a boulder bullet is launched and misses its target, roll 1d8 to determine the adjacent square in which it lands. Once it has been thrown and has expanded, a boulder bullet loses its magic and remains boulder-sized thereafter.
Pathfinder Player Companion: Ranged Tactics Toolbox © 2014, Paizo Inc.; Authors: David N. Ross, David Schwartz, and Kaitlyn Sprague.