On the level called "Intercept Nasri the Arms Dealer" there is an area that you can pick up unlimited ammo. When you finish the objective "Defeat Nasri's Guards" do not leave that room. There are three sets of stairs with a door behind two of the and one with a table across the top. In front of the table is an ammo pick up. This pick up will res-pawn every thirty seconds indefinitely. The type of ammo is random.

During "Investigate Marburg's Villa", in the garden at the end of the level there are two ammo piles on the north and south sides that re-spawn if you move back to the doors.