Talk:Akashi's Improvement Arsenal/@comment-24786587-20150502191751/@comment-25534439-20150504135758

Was just talking about this with someone else. Such bonuses are hidden, and determining whether or not there is a hidden +1 Hit stat on a +10 equipment is atrociously time consuming (around 1000 sorties time consuming). Determining a hidden FP bonus is far easier (which is why we have some numbers). So we can only consider the possible options and whether it is worthwhile to upgrade in each circumstance. One of four possibilities exist based on the presence or absence of a bonus to FP and a bonus to Hit.

If improving provides neither +FP nor +Hit, Upgrade for the higher Hit and FP of Type 1.

If improving provides +Hit only, Upgrade for the higher FP

If improving provides +FP only, Upgrade for the higher Hit

If improving provides both +Hit and +FP, don't upgrade.

Given that no other equipment is yet known to provide double bonuses for improvement, the last case would make improvement on shells exceptionally effective. Personally, I doubt that would be the case and thus I would suggest upgrading from +10 Type 91 to Type 1.