Enable "both"(or just %, doesn't matter) in the per player section for ammo and set how much you want to load, i.e 80 mags, so you set "ammo load, percentage" to 80
For fuel use the /f4m.max_percent command like it says on the main page, i.e /f4m.max_percent 20
Useful if you're using AI combat vehicles, this will load 80 ammo and 20 fuel as a result
