Ammo recovery rate refers to the chance that your ammo (bolts, thrown weapons) will drop on the floor after use for you to pick up and re-use.
Of course I've failed to disarm a 45% chance trap 6 times..... so it really depends on how much Krong wants you to get your bolts/thrown weapons back.
I think they should make the killing bolt 75% drop with level 3 archery. Most of the time I don't even kill stuff with bolts.
What's the base percentage for drop before adding any of the abilities? Also if the ammo recovery rate only gives back the killing bolt 15% is still pretty poor. It should be for every ammo fired,not just the last one,so each arrow/thrown item has a chance to drop under the monster regardeless whether it hits or not.