
Twomugg Aleslosh |

Gunslingers target touch AC, and people notoriously ban them because of this obvious power gap, if not because they break setting immersion.
Just because he can do good damage with his guns doesn't mean he's a good switch-hitter. Against enemies with stupid-high AC (which he probably doesn't have Weapon Finesse or equally-magical side weapons, meaning his to-hit bonus isn't anywhere near as high enough to reliably hit), or Damage Reduction, his side weapon would prove as ineffective as crying over spilled milk.
First, I think the combats you are relating are sounding like either a)your DM plays monsters like they are an opposing football team, lining up perfectly or b) you have no idea how to position your character.
Second, Gunslingers do have access to the Bolt Ace archetype which changes out the guns for crossbows and you can apply all of the archery feats.
I very rarely see a combat where we run face up against an equal line of monsters. We typically get scattered all over the battlefield and the archer is, bar none, one of the most critical components. Are you telling me that every monster you encounter is within move range of your fighters? No enemy takes an elevated position that your melee can't reach?
In my last campaign night, the party encountered 7 kobolds - 1 caster, three brutes and three snipers. The snipers ate the party, and pretty much the only way they got taken out in their 30-foot-high tree perches were the ranged combatants.
So, when you say ranged combat isn't feasible, I truly have no idea what you are talking about.