| Migobrain |
One possibility would be to simply remove the misfire mechanic from advanced firearms. You could rule that rifles, shotguns, and revolvers don't misfire, but keep the misfire mechanic for early firearms. Of course IRL all guns can hangfire or misfire, but Pathfinder doesn't deal with broken bowstrings or other major weapon failures, so I think you would be well within your rights to rule advanced firearms don't misfire.
Other than that, use the "Commonplace Guns" setting from UC for pricing and modifications to the Gunslinger Class. Gun Training at first level rocks.
You might also want to consider adding double rifles and repeating rifles to your campaign. Double guns were extremely popular during the last couple of decades of the 19th century, (In Victorian England, double barreled shotguns were very popular for fowling/wingshooting and large caliber double rifles were popular for big game hunting.) The Winchester repeating rifle was also extremely popular.
yeah, i have tought about that, but what to put in place of that in the gunslinger class? because of nothing works having anti-misfire rules in the class, maybe adding thins like scopes and silencers, and where anti-misfire mechanics are giving things like speed of changing them or things like that, toughs?