Gunslingers automatically gain the Gunsmithing feat at level 1, which allows them to craft ammunition at a reduced price. This seems like a rather important feat.
Unfortunately, the Guide to PFS Organized Play says the following about crafting:
Additionally, except for specific examples cited in this guide or the Pathfinder Society FAQ, the Craft skill is not legal for play and crafting of mundane items is not allowed in Pathfinder Society.
The "specific examples" in the document only refer to using Craft for your Day Job, and the FAQ only discusses Craft in the context of alchemists.
Do PFS gunslingers really have to buy ammo at full price?