Not sure if this should be suggestion or balance. Please move it if need be.
Guns feel like they're in a very weak position right now. Why?
1)Generally low scaling and damage
They don't particularly have any skills that does % SWA, making the low scaling just completely weaken their damage on all accounts. It could be argued that their scaling is low due to range, however mages can have nearly the same range with 120-150% scaling tome combined with un-dodgeable (I know you can evade but it still does damage) spells with choices of AoE. *edit* I nearly forgot. Their damage is actually even considered lower in PvP. Since every bullet is counted seperately, it applies Matador's feel no pain or just flat out DR in general to each shot. That could be a potential 60 damage cut off (or just 0 if each bullet hit less than 20) right off the bat.
I suggest either creating a class that is fully focused on gun skills or just upping their scaling in general. Maybe 20% higher scaling on each gun?
2)Little "special" effects
As far as I can tell, there are only 3 really used guns with effects. Corvis cannon for wind damage, Quick draw for turn order (and rounds), and then Ryeser for lowering momentum which can be countered by just having rubber gear. Excel weapons effects are okay as well, but considering it takes 2 turns to fully charge, but then can be negated by null shell makes it hard to actually use them against any gunner (since most seem to go MG or DH).
I would suggest adding more innate effects for each weapon.
Shotgun: If a shotgun has 3 range, if you are within 1 or 2 range your damage increases, but if you are 4+ range away your hit increases as bullet spreads. Maybe make them into axe type weapons? Not really sure if that would be needed but would be interesting.
Handguns: Perhaps steal Quickdraw's turn order/UL as an overall, without stacking. Or you could turn them into fist weapons for some close range gun combat creating synergy with monks.
Rifles: Negates the longshot penalty and instead gain damage, crit, and hit chance for being further away. You, like bows, gain a close shot penalty. Perhaps also turn them polearm like weapons, as if there were a bayonet on it.
3)Not very much variety in terms of weapons
Again, as far as I can tell very few different guns are used (not that there are much gun users). I believe the list is: Quick draw, Excel sniper, Moonlight mercy, jackhammer, handgun, ryeser, and corvis cannon. I'm no expert so maybe more are used.
Create more guns with their own "role" in combat. I can't think of much, these are just two suggestions.
LMG/HMG: Perhaps with a support fire role, you can "prep" your attack at an enemy. If the enemy plans on moving you can shoot and lower their movement, or if they want to attack an ally they'll have lower crit chance as they're going for a quick strike rather than precise. You can even make it that when an ally goes for an attack they have increased power/crit chance since you'll fire at the enemy near the same time distracting them.
Assault rifles: The mid range damage role. They can gain increasing damage against the same target.
4)No actual class in my opinion
As much people agree, the current gun classes are quite spread out and even makes it impossible to destiny if you want to mix them. My opinion is there just isn't any gun class period. The closest would be MG, but they focus more on using magic shells rather than actual skills/tactics. Demon Hunter seems to be more focused on a sword and gun (since we know what that's from) and only has 2 moves in general for guns. Both of which are just some AoE.
I personally want to be a gun man that doesn't have to somehow get in contact with the black market and get these special shells or whatever demon hunter could really be. A simple gun class with skills, dodges, maybe a shovel smack would be nice.