So now I got the concept down for dwarf guntank/pistolero
How can we get him to fire as many rounds as possible as her progesses through levels. What's the feat tree?
Your first problem is figuring out how to reload your guns.
Please search on the forums as this has been discussed to death. And look at recent threads because the Pathfinder Development Team has purposefully nerfed a lot of options to make it more difficult to perform the shenanigans some people were doing.
Which was/is two weapon fighting with double barrel pistols.