Well, I'm playing right now similar build.
First - I would not take Grenadier and Mad Chemist, at least in early game.
Looks like there are better feats for such build.
Then you can consider about Sharpshooter, which require 10 Perception.
I don't know if it worth it or not, but I did that.
I can say that .44 Hammerer is my main weapon, with 7.62 Hammerer as secondary.
I'm using firearms for now (and possible I'll use it till the endgame), but I don't pick feats which are specifically for them.
Instead, I picked Aimed Shot (guaranteed crit on first turn) and Practical Physicist (and Sharpshooter, Critical Power and Opportunist, Execute will be next).
Pistols get good crit chance, they can damage as good as sniper rifles (at close range), and can fire faster, have special tricks like Electro Pistol, or Plasma Pistol (the last is devastating in comparison to firearms), chemical (didn't used it yet).
Also pistol uses not so much bullets obviously, which mean less hussle which is good for me.