I have a few bits of information that I would like to share with you gunslinger aficionados. Firstly, keep in mind that these rulings are using the Open Gaming License from Pathfinder RPG and using abilities from 3.5 Dungeons and Dragons to make the gunslinger a little more proficient until further test material comes out or a finished product has been worked.
For those wanting more gun choices than the two listed in the beta testing there are a few sources you can look up. In the Pathfinder Chronicles Campaign Setting, on page 212 there are 6 types of firearms with variant rules for 'exploding dice' that, depending on your GM, can be used with the misfire ruling from the Alpha testing of the gunslinger.
Not quite so common is a Monte Cook product entitled Ptolus, City by the Spire. This huge city/campaign module/setting is 3.5 compatible and created from the famous Monte Cook himself! Detailed under the technology chapter( page 559, chapter 29) there are 13 more firearms with rulings for double and triple barreled guns, repeaters, cannons, and many more. There are a few magical enhancements to guns as well in this book, one of which, in particular, is SUPREMELY useful for all us gunslinger players thusfar. Let me introduce you to, the Demon gun.
Demon Gun: Rather than a dragon's head(the standard pistol depicts a dragons head for the end of the barrel and are thusly named dragon pistols), this +1 dragon pistol sports a demon's head at the end of its barrel. The gun itself is a demon bound magically into the form of a gun. It produces its own ammunition internally, so the wielder can fire as many times per round as he has attacks, and it never needs reloading. Twice per day, upon the wielder's mental command, it can produce an unholy bullet.
Moderate Conjuration. CL 10th; Craft Magical Arms and Armor, Summon Monster III, Unholy Blight; Price 24,550 gp.
This opens up gateways for alot of players to have that high BAB and use it to its full potential. If this item is out of your price range i have an even cheaper solution for you.
Located in the 3.5 Dungeons and Dragons product entitled Magic Item Compendium, for 8,000gp you can buy yourself a pistol or musket with a weapon enhancement named Quick Loading.
Quick Loading: +1 Bonus, CL 9th; Moderate(DC 19) Conjuration.
(Please note this is designed for crossbows, but with the beta testing they look to be improving feats related to crossbows and including firearms in them, myself as a GM and fellow GMs i play with allow this use of the weapon enhancement)
A quick loading crossbow accesses an extradimensional space that can hold up to 100 bolts(or bullets), allowing you to reload the crossbow more rapidly than normal. Reloading a hand or light crossbow is a free action, and a heavy crossbow as a move. Different types of bolts can be held in the extradimensional space, and you can select freely from these when reloading the crossbow. Adding or removing a bolt by hand from the extradimensional space is a move action. Prereqs: Craft magic arms and armor, Leomund's secret chest, shrink item.
This works especially well if you have the rapid reload feat making pistols a free and a musket a move action.
Last note, if you are looking along the same lines as wanting to keep everything Pathfinder RPG specific and do not want to use these tools[and keep your pockets full >:) ] Keeping in mind i am allowing my players to use crossbow feats for firearms as well(mechanically i think this makes sense and apparently so does Paizo dev team) there is a feat in the Advanced Player's Guide Entitled Crossbow Mastery.
Crossbow Mastery (Combat)
You can load crossbows with blinding speed and even fire
them in melee with little fear of reprisal.
Prerequisites: Dex 15, Point-Blank Shot, Rapid Reload,
Rapid Shot.
Benefit: The time required for you to reload any type
of crossbow is reduced to a free action, regardless of the
type of crossbow used. You can f ire a crossbow as many
times in a full attack action as you could attack if you
were using a bow. Reloading a crossbow for the type
of crossbow you chose when you took Rapid Reload no
longer provokes attacks of opportunity.
Special: Starting at 6th level, a ranger with the archery
combat style may select Crossbow Mastery as a combat
style feat.
Thank you for your time and please don't hesitate to give me your point of view on the subject or anything you find to help while it is still under development :)
Found another source book for people to try looking at.
Its from the Legends and Lairs source book entitled sorcery and steam.
D20 compatible, more of a splat-book but has some pretty decent rules for firearms, steam powered armor, ext. new skill munitions where you can reload faster, perform tricks, ext with a high enough DC. Musketeer is a base class in that book, very reminiscent of the gunslinger but more of a anti gunslinger gunslinger. ignore cover bonuses, bonus to AC vs ranged attacks close to the monk unarmored ac progression. reloading durring a move action like quick draw, ext. Definatly should check it out if you are worried about waiting for round 2 of the play-test.