Need Ammo Advice for an Eldritch Archer Magus

[Nosta]

I have 1200 Gold to spend and need to buy some ammo for my +1 Reliable pisto
I am not sure what type I should get.

[Eldaran]

I'd just stock up on all the relevant materials: cold iron, silver, adamantine. Maybe get a few holy bullets depending on your alignment.

[Snowbluff]

I'd just stock up on all the relevant materials: cold iron, silver, adamantine. Maybe get a few holy bullets depending on your alignment.
This. However, the wepaon should get Distant and Holy on it as a rule.