Have damaged (worn, damaged or badly damaged) and pristine ammo. Split damaged and pristine ammo into small piles and repeatedly combine small ammounts of pristine with 1 small pile of non-pristine ammo until it is all pristine(badly damaged ammo will become damaged, then worn, then pristine.) This can be done repeatedly with most likely unlimited rounds of damaged ammunition, always coming away with larger amounts of pristine ammo. Combining all ammo at once (in the case of pristine vs badly damaged) will average out the pile (35 pristine rounds + 35 Badly damaged come out as damaged.)