[MatthewRayfield]

I found ammo in boxes next to the guns. But I didn't at first see it as ammo, I thought it was some kind of barrier and moved on. So maybe it's a matter of making that more obviously ammo looking ? Like a stack of bullets ?

[TeMPOraL]

Seconded. It took me a while until I noticed that the small colored squares are ammo - I only realized it after I noticed a label popping up and disappearing as I moved over them.