House Rules, Character creation, Misc rules
Spell modifications, clarifications and errata
Magic Stone
Elemental Evil Player's Companion , pg. 160
Regardless of being used in a sling, or thrown, the magic stones have a range of 60/120. When thrown, you use your spell-casting modifier. When using a sling, you can use your ranged attack modifier to hit. As a clarification, the stones deal bludgeoning damage, not magical, for the purpose of damage vulnerabilities and resistances. The spell does not work on musket bullets or weapon ammunition, so can't be used with firearms.