So i've seen a lot of combinations of mixing spellcasters with guns but most of them to work had to focus more on either martial or magic combat. The Arcane Gunslinger is good at both (not perfect though). I hope that no one already posted anything similar to him ;D.
Nad Ilztril
Drow: Gunslinger (mysterious stranger) 7/ Rogue 1/ Assassin 1/ Wizzard (spellslinger) 1/ Arcane Trickster 10
My rolls (standard) / 15 point buy:
Str 10 / 7
Dex 19 / 18
Con 10 / 10
Int 12 / 14
Wis 12 / 9
Cha 15 / 15
(+4 via level progression)
BAB +16
Traits: Magical Talent - Mage Hand, rich parents
Feats (11): rapid reload, weapon finesse, point blank shot, rapid shot, desperate evasion (gunslinger level 7 feat), extra grit, arcane armor, critical improved, craft wondorus item, skill focus: survival, eldricht heritage: orc bloodline
Gear: +1 Rifle or +1 Musket with far reaching sight, sniper googles, +1 pistol or revolver, +1 rapier
So what exactly he can do?
For example snipe target from 160 feet - 1st increment (rifle range 80 feet x2 from spellslinger's "distance" mage bullet) dealing with Dead Shot deed: 5d10 + 7d6 sneak + 15 (focused aim deed), (4d10 +12 if your DM wont let you add rapid shot to total potential attacks number), and you roll d20 five times, with crit chance 19-20, so there is quite high chance for crit :] If enchance gun with "shocking burst", we get: 20d10 +8d6 + 3d10 + 15 on crit!
Oh, and your target is flatfooted and denied of armor bonus to AC, and you even dont need to be hidden to sneak attack him (impromptu sneak attack from AT). Whats more you can try assassinate him, though Fort. DC 15 isnt hard to fail, but always something. But attack like this is costfull (2 grits), but no worries, Arcane Gunslinger is 11 lv. caster, disintegration? maybe once per day only, but quite deadly 22d6 + 7d6 (sneak attack) + 29 (orc bloodline) and if you chose to have just one arcane gun you get x3 on crit, but i preffer to have two arcane guns. Besides this, he can turn invisible, throw darkness, use variable mage bullets, shot cone/ranged touch spells from his gun, teleport and all the cool stuff that every proper Arcane Gunslinger should have :]
Please let me know if you have some ideas to upgrade this character, or if you noticed some mistakes.
How i was able to chose Arcane Tricster as prestige class, with just one wizzard level? - Drow starts with Darkness spell like ability (level 2 arcane spell) + trait Magical Talent (mage hand spell like ability), wasnt sure if its possible but i checked on Paizo FAQ, and it is 100% legal :]. If you wont like to play evil drow, you may chose for example elf (look for traits with lv.2+ sp), and replace assassin with master spy.