Alright, so I'm going to start simple with the Sereth Rifleman Gunslinger Archetype. I won't fill the post with background info about the archetype, just class info. This archetype is based off of the Musket Master archetype for the Gunslinger class found in Ultimate Combat. I considered using the Cavalier archetype Musketeer as the basis, as they gain a gifted firearm, which would fit better with the lore of the Sereth Long Rifle, but yeah. Actually, I think I'll start by listing the info for a the Sereth long rifle first.
The Sereth Long Rifle does 1d12 damage, crits on a 19-20 (most firearms crit only on a natural 20) and does x4 damage (the norm for most firearms when not using the scatter ability). It has a three round capacity, misfires on 1s, and has a 150 ft. range increment. It also has the advanced special quality along with the masterwork, sights, and scope upgrades. Basically it is a well made rifle with a long ass barrel that can only easily be wielded by races with long ass, multi-jointed arms like the Sereth. It requires the Exotic Weapon Proficiency (Sereth Long Rifle) to wield without a penalty to attack rolls.
Alright, like I said, this is basically the Musket Master archetype.
Weapon Proficiency: A Sereth Rifleman only gains proficiency with two-handed firearms, this includes the Sereth Long Rifle. He must take the Exotic Weapon Proficiency (Firearm) feat to gain proficiency with one-handed firearms and firearm siege engines.
Deeds: The Sereth Rifleman swaps a pair of deeds for the following.
Sniper Shot: At 1st level, when the Sereth Rifleman hits a target with a Sereth long rifle, he can spend 1 grit point to deal 1d8 points of extra damage on a hit. If he misses with the attack, he grazes the target, dealing half the extra damage anyway. He must choose to spend the grit point before he makes the attack roll. This is precision damage and is not multiplied if the attack is a critical hit. This precision damage increases to 2d8 at 5th level, to 3d8 at 10th level, to 4d8 at 15th level, and to 5d8 at 20th level. This precision damage stacks with sneak attack and other forms of precision damage. This deed replaces the Gunslinger's Dodge deed.
Fast Rifleman: At 3rd level, as long as the Sereth Rifleman has 1 grit point, he can reload any two-handed firearm as if it were a one-handed firearm. This deed replaces the utility shot deed.
Rapid Reloader: At 1st level, a Sereth Rifleman gains Rapid Reload (Rifles) as a bonus feat.
Long Rifle Training: Starting at 1st level, a Sereth Rifleman increases his skill with Sereth long rifles. He gains a bonus on damage rolls equal to his Dexterity modifier, and when he misfires with a Sereth long rifle, the misfire value increases by 2 instead of 4. Every four level thereafter (5th, 9th, 13th, and 17th), the bonus on damage rolls increases by +1. At 13th level, a Sereth Rifleman never misfires with a Sereth long rifle. This replaces firearm training 1, 2, 3, and 4.
Alright, nothing exactly game breaking there. I kept the majority of the Musket Master archetype in play, modified some stuff to match up with the Guns Everywhere rule we use. On that topic, it seems like a gross oversight that Paizo didn't include alterations that needed to be made to the various archetypes in the event the Guns Everywhere rule is used. Most of the Gunslinger archetypes have various effects tied to firearm training, the Gunsmithing feat, and battered firearms. The Guns Everywhere rule changes those a bit.
Anyway, I kept Fast Rifleman from the Musket Master, but instead of using the Steady Aim ability, which would just further increase the massive range of the Sereth long rifle by a whopping ten feet, I used a variant of the Up Close and Deadly deed from the Pistolero archetype. I upped the damage on it to 1d8 from 1d6 to kind of go along with the increased punch of rifles over pistols, but I suppose keeping the d6s as the precision damage wouldn't hurt. You don't get bigger sneak attack die for using an axe instead of a dagger, so maybe when it enters the campaign book I'll make it d6s.
Granted, most of the punch from this class comes from the weapon they wield. I mean, the sights make its long range much more attractive. I mean, you can shoot targets 1050 feet away with only a -5 to your attack roll (-6 for six range increments beyond the first, +1 for masterwork), so you can essentially reach out and touch anyone on any battlefield. The scope on the weapon isn't a big deal to me, it just increases the threat range by one, but if I remember correctly, you can't combine the keen weapon ability with improved critical feat, so I would think that carries over to the scope upgrade, as it is based on the keen weapon ability. The three round capacity isn't a big deal either, with metal casings and Quick Reload, most firearms can be reloaded as a free action. Gob does, which is why I only randomly mention he is reloading in combat. The Sereth long rifle would reload as a move action, but the Fast Rifleman deed takes care of that.
I dunno, I think I'm pleased with it. It gives the archetype a little flavor beyond that of the normal Gunslinger, but doesn't completely alter the way the class plays and functions.