Ok so here is the situation. One of my players has made a gunslinger. Musket Master is the archetype. He is lvl7 atm. One of his goals for this character is to create a better gun for him to use and introduce it into the world. He has asked me what would be the benefits of a lever action rifle.
For the life of me I can't think of anything useful that this gun would be able to do that his class and especially with his archetype can't do anyways.
If anyone has any ideas as to what would be a good special ability I'd appreciate the feed back. The best thing I've come up with is being able to make an attack of opportunity on someone that moves through his occupied area. But that doesn't seem right some how.
Eh... there's already a rifle in Pathfinder, and since that's the only "rifle" available, I assumed that the one weapon covers all types of real-life weaponry. A lever-action modified version may not be necessary.
Making attacks of opportunity with a ranged weapon is already possible with the Snap Shot feat.
The real questions you should ask (yourself) are "do I really want 19th century weapons in my game?" and "how the hell does the player manage to make the developments from over three hundred years in a few weeks while adventuring?". Oh, and of course "what will I do when the other players quit the game because I allow one player to get a ridiculously anachronistic weapon that utterly wrecks game balance?"!
The rules for guns currently (and probably will continue into 2nd edition) suck in general.
But I had some rules for a sort of "Wild West" as alternate rules for firearms.
For lever-action rifles and revolvers I set it so that you could reload one bullet as a Move Action, half the Capacity (rounded up) as a Standard Action, and total reload for a Full-Round Action. Quick Reload made it so that you could reload one bullet for as a Swift or Immediate Action, half the Capacity (rounded up) as a Move Action, and total reload for a Standard Action.
Also Lever-Action Rifles can also be fired (but not reloaded) in one-hand at a -2 penalty, you can even dual-wield `em if your nuts enough to try (or are built for that kind of crazy stuff), as they count as a one-handed weapon for the purpose of how much your penalized in two-weapon combat.
That's all I can give you.
The real questions you should ask (yourself) are "do I really want 19th century weapons in my game?" and "how the hell does the player manage to make the developments from over three hundred years in a few weeks while adventuring?". Oh, and of course "what will I do when the other players quit the game because I allow one player to get a ridiculously anachronistic weapon that utterly wrecks game balance?"!
Just saying but they were more late 18th century, but more importantly you may have forgotten that the Pathfinder also has SUPER ADVANCED SPACE AGE Technology too.
Historically guns made ranged combat more accessible to the untrained folk not the ones already highly trained. So a lever action rifle would likely make reloading faster and he has likely already spent the feats, class abilities, etc. on getting free reload.
If he built a lever action rifle it would be undeniably a better weapon than the currently available muskets. But we all know he wouldn't be happy with it since it wouldn't make his character any better.
Soo... my advice is not thinking in terms of what is best next historically. Either look at his character or ask him about what would be a gun that would make his character better. The answer is normally going to be some mechanical advantage that is replicating a magic ability of some kind. That's good. Base the improved weapon off that... prototype weapons SHOULD be expensive and keeping it inline with magic effects helps keep some semblance of balance in place.
Make sure you think about how you want it to stack (or not) with magic effects as well. Weapons are required to be masterwork to be made magical but the +1 to hit from being masterwork doesn't stack with the +1 to hit from being a +1 weapon. I would try to follow that same vein.
Anyway... that is my advice on it.
The simplest answer I could give him is "it would be similar to a repeating crossbow, but your build already makes that unnecessary". And honestly, the pepperbox rifle already touches on that role.
The only real problem here is that he might insist on advanced firearm rules (which would be quit a boost to power). Whether or not that jump is appropriate for your table is up to you. Personally... I wouldn't do it. Firearms alone can be a handful already, no need to add fuel to that fire.
If he wants to 'say' he has a repeater, then let him. But in terms of gamebalance, muskets are already fine. Hell, just rebranding the musket as a cartridge based item would make it easier to mentally accept for free action reloads.
Just saying but they were more late 18th century
Well, I was going by wikipedia, "Probably the first lever-action rifles on the market were Colt's 1st and 2nd Model Ring Lever rifles, both cap and ball rifles, produced by the Patent Arms Mfg. Co. Paterson, N.J.-Colt's Patent between 1837 and 1841." I'm sure there were earlier experimental designs, but since the player wants to "introduce it into the world", we're talking about a market-ready weapon. The player is probably thinking about the rifles used in the american civil war, like the Spencer repeating rifle and Henry rifle, both designed in 1860 (the two of which Wikipedia calls "the first significant lever-action designs").
you may have forgotten that the Pathfinder also has SUPER ADVANCED SPACE AGE Technology too.
Well, there's a difference between playing e.g. Iron Gods where you know to expect futuristic weaponry (and can plan your character accordingly), and suddenly having advanced firearms that make every other martial a joke.
Seriously, don't underestimate the game-warpingness of advanced firearms. Even if using the rifle from the book (which is not yet as advanced, actually), as a +2 weapon (+1 reliable) it never misfires, is a free action to reload with Rapid Reload, and targets touch AC at 400 ft.
On a side note, your use of an abnormal action progression for reloading (normally, it's full-round -> standard -> move -> free) makes your design worse than a musket, because if you can't reload a firearm as a free action, it might as well not exist in Pathfinder. THis of course flips over when you use Shadowshooting, at which point you got TWF at good range.
Historically guns made ranged combat more accessible to the untrained folk not the ones already highly trained.
That's true for real life early firearms, but not for Pathfinder firearms. Here, they do basically the exact opposite, they reward heavy investment (i.e. 'training') to an extreme degree. This is actually even more true for early firearms, advanced firearms need way less specialized training (basically, switch Manyshot for Rapid Reload on an archery character and you're good for a rifle).