Jhin's reload time should scale based on the amount of % Damage he is receiving from the Crit+Att Speed part of his passive
Lets say you're getting a +275 Bonus Attack Damage from your passive with full build+level 18
Your reload time is 2.5 seconds I believe so it would read his--
275 Bonus attack damage from passive and multiply that by .0025 as the ratio, that would be his reload time going from 2.5 - 0.6875 = 1.81
DEATH IN 4 ACTS: Jhin's basic attacks utilize ammunition and his attack speed cannot be improved except through growth. Jhin can attack 4 times before having to [1] reload for 2.5 seconds, and automatically does so after 10 seconds. The reload timer is reset back to 10 seconds upon attacking or using an ability. The reload timer is reduced by 「 0.0025% of his bonus attack damage from EVERY MOMENT MATTERS.
EVERY MOMENT MATTERS The final shot is a guaranteed [2] critical strike that also deals 15 / 20 / 25% of target's missing health bonus physical damage.
EVERY MOMENT MATTERS: Jhin's [3] critical strikes deal 25% reduced damage, but grant 10%(+ 4% per 10% bonus attack speed) movement speed for 2 seconds.
Additionally, his attack damage is increased by 2% - 40% (based on level) (+ 4% per 10% critical chance) (+ 2.5% per 10% bonus attack speed).
It wouldn't break him early/mid game, but it would allow players to not feel completely useless and squishy as hell late game. You could not exploit it either because it would require you to build normally in order to receive any benefit.