You need way more Treasure Hunt. You should easily be able to hit 200+ without using optimized equipment or Tactica. Your dedicated Treasure Hunt division should eventually aim to have double that.
The following formula is used to calculate drop "value":
(A + B) * (C + D)
A = highest enemy LV defeated
B = highest total Treasure Hunt of any division (only counts living allies)
C = highest enemy Cost defeated
D = number of units defeated, up to 6
Drops are calculated per division, but use the highest values among the battalion. For example:
D1 has LV 100, Cost 10
D2 has LV 120, Cost 5
D3 has LV 100, Cost 12
If you defeat all three enemy divisions, the game will calculate drops based on LV 120 and Cost 12 for the entire battalion.
You need a minimum drop value of ~9900 before the game will have a very slight chance to drop R9 ore, and ~12500 to drop the first piece of R9 equipment (~15500 for the full range of R9 equipment). Bounty hunter never becomes useless because you can always trade up.
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