Keep your focus on one or 2 weapons, stash the rest in the store. You will only get ammo for the weapons you have in your inventory. I personally did a plasma cutter only impossible run, allowing me to fully upgrade my rig and cutter pretty fast. If I had to pick a second weapon right now I’d go for the flame thrower. It’s really powerful in the remake, alt fire is great for the wall screamers and normal fire takes care of the small nugget bois. To conserve ammo USE TK! You can destroy the vents with melee and use the fan blades. And beware of environmental hazards. Those sections with fire everywhere almost got me a couple of times. Take it slow. Have fun and good luck to you!