Ammo Scavenger is a gear perk that gives you extra ammo whenever you pick it up. It helps when you run weapons that burn through rounds or use special ammo types.
Each ammo pickup gives you more rounds than normal, so you go longer between trips to ammo boxes or Arms Dealers.
Wear one of the gear pieces that carry it: Moto Urbano Gloves. Each piece only takes one body slot, so plan around the other perks you want.
Worth it for machine gun and launcher users, or if you often run low in long base fights. Less useful if you mostly use a bow or a pistol.