Gunslinger Class Help!

[IZ42]

I'm currently building a gunslinger focusing on long-range damage, and decided to come here for help. My question is, are there any good PrCs, or just regular classes that I can use that mesh well with Gunslinger? 3.5 Material is pretty much a no-go, but there is a tiny chance I can convince my GM of it, so keep those suggestions to a minimum, please.

Some starting information:

- Have not decided between base Gunslinger or Musket Master yet, open for discussion on that, but I'll likely be able to reload as a free action anyway(rapid reload+cartridges I think drops it to a free action, might be wrong on that), so one of the archetype's features would be relatively useless.
- Advanced and Modern Firearms allowed, I want to be using a rifle mainly, but am up to secondary weapon suggestions.
- Starting Level 19, non-gestalt.

[grarrrg]

I'm currently building a gunslinger focusing on long-range damage, and decided to come here for help. My question is, are there any good PrCs, or just regular classes that I can use that mesh well with Gunslinger? 3.5 Material is pretty much a no-go, but there is a tiny chance I can convince my GM of it, so keep those suggestions to a minimum, please.

Some starting information:

- Have not decided between base Gunslinger or Musket Master yet, open for discussion on that, but I'll likely be able to reload as a free action anyway(rapid reload+cartridges I think drops it to a free action, might be wrong on that), so one of the archetype's features would be relatively useless.
- Advanced and Modern Firearms allowed, I want to be using a rifle mainly, but am up to secondary weapon suggestions.
- Starting Level 19, non-gestalt.

Starting at 19? Then Gunslinger 11 is a definite, may as well bump that to 12 for the Bonus Feat and rounding off the Save bonuses.
Being able to get Signature Deed (http://www.d20pfsrd.com/feats/general-feats/signature-deed-grit) is usually well worth 11+ levels.


As far as PrC's go, the only one that directly does anything with Guns is Shieldmarshal (http://www.d20pfsrd.com/classes/prestige-classes/other-paizo/e-h/grand-marshal). It stacks 1/2 levels with Gunslinger for Gunslinger Deeds, and grants a few decent bonuses itself. But Straight Gunslinger is good too.


Musket Master yet, open for discussion on that, but I'll likely be able to reload as a free action anyway(rapid reload+cartridges I think drops it to a free action, might be wrong on that), so one of the archetype's features would be relatively useless.
If reloading Muskets the Fast Musket ability from the archetype _IS_ necessary.
2-hand Firearms reload as a Full-Round action. Fast Musket drops it by one step to Standard, Rapid Reload drops that to Move, and Cartridges drop that to a Free.
1-hand Firearms are already a Standard, so they're good with Rapid Reload+Cartridges.

Of course, all of this is kind of a moot point because:

Advanced and Modern Firearms allowed
Which already reload much better than "old timey" guns do.

[IZ42]

Grand Marshal looks pretty cool, seeing as my concept in mind is an intelligent sniper with actual common sense instead of what most gunslingers have. Should I pick up a few levels in rogue for the sneak attack damage or go Gunslinger 11/Grand Marshal 8, or some variation thereof?