For long-term stays in nullsec, laser-using ships like the Armageddon, Apocalypse, Zealot or Legion have the added benefit of not Rohan Gold consuming ammunition. Similarly, dedicated drone ships like the Dominix and Ishtar will never need to restock on ammo, with the added advantage of being able to field any damage type they want. If you're using a ship that needs ammo, you'll need to keep a stock of it nearby. For ratting in NPC systems or your alliance's territory, you'll have the luxury of being able to store ammo in the nearest station. If you're ratting somewhere more remote, I'd recommend hauling a giant secure container or two full of ammo to the target system and anchoring them in space for easy respelling.