I've noticed that a lot of people have been complaining about the damage that the guns used by the gunslinger does (quite the mouthful), so I went and looked back through some of the old stuff that came before the gunslinger and lo and behold there was the pathfinder chronicles campaign setting.  True, some of the rules are a little dated now, what with Pathfinder RPG but the section I wanted to draw attention to was the section called Firearms.  Now we have rules for misfire and after a quick double check, we don't have the exploding dice rule.  
Basically when rolling the damage dice of a gun you kept rolling damage if you rolled maximum dice (in the case of the playtest this would be 8 on a d8), which I think would help balance the some what low range and other problems that people have pointed out.  
From a fluff point, Alkenstar have other types of firearms due to the lack of magic (it being non-existent) so they have developed fantastical weapons of war.  That said, I think it would be fair to say that they musket and the flintlock pistol are but the tip of deep and dangerous iceberg of destruction.
Just some food for thought for you all to think over.  
Please try not to eat me
Nighteyez