Let me first say that I really like the new gunslinger. It's interesting, flavorful in it's own right and looks to have a great feel in it's class abilities. So I'm looking forward to it.
That said; there are some minor issues that could use a tweak or a twinch.
Starting from the top I will have to mention the skills. Adding Perception would seem like an appropriate thing to do, since the class would make an excellent sniper with a musket and would therefor need to be able to spot it's targets from afar.
It would also suit the class to have 4+int mod skill points, instead of the regular 2. The class seems to be meant as a suave, skillful kind of swashbucklar, not a dumb, clumsy warrior. In that aspect I would also consider adding Diplomacy and Knowledge (Nobility) to the skill list.
The "Firearm" ability is very appropriate, if a little unbalanced on the economic side. But I wouldn't change it, it's very much needed to allow the flavor of the class.
About Grit; I'd find another name as soon as humanly possibly. The name conjures images of Clint Eastwood (whom I kinda like as an actor) standing in the dusty street of a small western town. It's not the kind of image I want to have when thinking of my my awesome gunfighter pirate robbing inner sea merchants.
Besides that, I'll join the people already advocating for the points comming from Charisma instead of Wisdom. And I must ask that the points benefit from ½ level, as the Magus' Arcane pool. As they are now, I would be very careful when I use my points.
All of the Deeds abilities are interesting and flavorful. But I'd probably go for shifting the "Targeting: Body" with the "Targeting: Head", since being hit in the head by a one ounce ball of lead is way more dangerous than being hit in the - probaly - armoured torso. Though having the wind knocked out of you by a lead ball is probably more akin to being Dazed than actually Confused. But as I've read it so far it doesn't cost Gri points to use this ability anyway, so downgrading it to dazed isn't a great loss. Besides, I'd much rather shoot for the more dangerous location and having that being the head would make it look great in a movie ;)
I like the "Brave and Tough" ability. It seems a bit unnessessary though, since it will take the Gunslingers Fortitude save almost to the same level as a regular Fighters, instead he would have about the same benefit for just having the Saves of a Ranger. The "Bravery" ability of the Fighter is still very Appropriate though.
A minor question on the bonus feats: Since the Gunslinger is a variant of the Fighter, it could be seen as he may use his bonus feats for Weapon Specialization. Is this correct?
Gun Training is great. But it seems appropriate that the bonus to hit should go up by 1 every time they get this ability for another firearm, otherwise they will inevitably end up being behind a regular bow-using fighter on both the hit scale, and attacks per round.
True Grit seems a little underpowered to me, but I can't think of anything better at the moment.
All-in-all a mighty fine piece of work. I applaud it.
Should I have missed anything important, I appologise, the flu isn't making this easier ;)