When I activate unlimited ammo, it acts as 'no reload' instead, and ammo still depletes. Tested with basic weapons (i.e. Sawed-off, crossbow), "H4mmer" "Marshall" and "magnum" all same result.
[Edited by woolhide, 10/7/2016 11:24:46 PM]
This. And when you pick up new weapons they have no ammo.