Forgive me, I have not taken the time to read all the posts here. I am tired and have to work early. But in reading the Investigator, if you take the Steel Hound Archetype, there is no modification in RAW for getting Studied Combat bonuses to your ranged attacks.
Also, with the Gunslinger Archetype - Bolt Ace, it's missed a LOT of stuff that would apply specifically to a crossbow that would/would not apply to a gun. In fact, I would say it needs to be a separate class with the same mechanics that would qualify for any existing Gunslinger class Archetypes. (As I am unable to make a Kobold Bushwacker that uses crossbows...as an extreme example)
Again, tired, on pain killers, just wanted to bring it up.