So I've been looking over the Occultist class and with the Battle Host archetype would a firearm wielding one be viable? I figured Half Elf race for firearm proficiency (whichever one you pick to use) and Gunsmithing for 1st lvl feat.
Other than that bit about the broken condition, the Battle Host can be a decent gun user. A fair amount of their focus powers work at range, and they have a lot of the good firearm spells on their spell list.
If he gets 2 misfires, his gun is destroyed. He can fix the first misfire in 1hr with gunsmithing. So going no dip route, he would also want to take amateur gunslinger. At which point, I think, a dip is the better choice.