So, I'm thinking of making a rogue sniper/ Spellslinger just because I happened to stumble along this archtype (usually I try and stay away from casters due to people wanting to play them so much). Any ideas of how to make this... actually good? Or should I stick with the rogue sniper/ waves oracle as I was planing?
Mixing a 3/4 bab class with a 1/2 bab class is going to leave you with issues hitting anything. Here's what I would recommend:
rogue (sniper)6 (9)/ Bard (arcane duelist)4 [7]/arcane trickster 10 [(7)]
The bard levels give you:
continues your 3/4 bab
good skill points
the ability to cast in light armor, which meshes with your rogue abilities
arcane strike to help damage output
combat casting
inspire courage +1 [+2]
[blade thirst, which helps beat DR]
[disruptive]
[arcane bond]
changes your casting stat to charisma which meshes better with rogue skills
access to bard spell list. This list is probably better than the wizard list for this type of character. you get spells to heal and buff and control the battle field all of which avoid enemy resistance/saving throws so your lower caster level won't matter as much
The rogue levels give you:
sneak attacks at 50 (60) ft
1/2 range penalties
3d6 (5d6) SA
3 (4) rogue talents
uncanny dodge
evasion
(improved uncanny dodge)
The arcane trickster:
Continues to increase your spell casting
adds 5d6 [(3d6)] SA
allows rogue skills at range
Impromptu sneak attacks 2/day
Tricky spells 5 [(4)]/ day
Invisibility 10rds/day [(n/a)]
SA on spells [(n/a)]
I would personally recommend going to 7 on the bard or going maybe a full 10 in the arcane trickster to keep your spell casting advanced. If you cut out at level 7 to add rogue levels you get 10ft extra range, +1bab and an extra rogue talent which is not worth giving up 5th level spells. If you want to play a sniper the extra range sounds good but I think that you really run in to an issue of diminishing returns. depending on the campaign you may be in doors or in a city where long range is difficult, also enemies will close distance pretty fast so all that extra range is useless after the first round. 50ft gives you the ability to stay out of the range of most melee enemies and behind your meat shields. I think the best option would be going to 7 in bard for more buffing ability with your performance. You'd lose out on 2d6 damage and adding sneak attack with you spells but you'd make up for it with increased versatility in and out of combat.
Your stats would go Dex>Cha>Str>Con>Int>Wis. Dex gives you a boost on your skills and adds to your to hit, Cha rounds out the rest of the skills and gives you spell casting, you'd want at least a 15 eventually, the rest are all secondary a bit of strength will help the damage but most of it is coming from the arcane strike and SA so not a big deal, Con is less important since you'll be out of melee for the most part, You have plenty of skill points so Int is not really needed and Wis just controls your saves.
With this build you want to realize that you are not going to be the star of the show, rather your job is to be the best supporting actor. You are the scout, the party face, striker, buffer and back up healer. You can start combats by getting a SA at range to take out the mooks or soften up the BBEG then as the enemies close distance you buff up your tanks or cast a spell to control the battle field. In later rounds you add damage with your arrows and heal if needed. You probably won't get many kill shots yourself but you'll make it a lot easier for everyone else in the party.