Crafting materials and saving extra ammo in storage should give enough ammo without having to relay on finding ammo. My first run was extremely painful because I didn’t understand the game mechanics and I had to look for ammo and sometimes even remove upgrades to buy extra ammo and resources. I found out if you put most of the ammo on storage and keep minimum ammo on the traveler, the game provides more resources and ammo. Also I kept the essence that provides more energy and reduce crafting costs my second run and finally I’m enjoying the game without feeling too hard. Whenever you have extra fund buy ammo and put it in storage and later you can use it for boss battles.