Mine wasn't River Kingdoms specific, but I'm sure it could function there. I was going with more of a Mana Waste or Nex theme. I'm not sure if I was within the word count parameters either. I built the class with the blunderbuss in mind, but I'm sure with DM discretion different abilities may work with siege weapons such as bombards.
Gunner (Alchemist)
The Gunner is an alchemist that specializes in artillery. The gunner combines range with the devastating art of alchemy. These skills make them particularly devastating during tactical combat. Whereas most alchemist’s have an affinity towards bombs and poisons, the gunner works with munitions and firearms in the pursuit of making them even more potent.
Class Skills: The Gunner gains Knowledge Engineering, but loses Knowledge Nature.
Weapon and Armor Proficiency: At 1st level, a Gunner becomes proficient in the use of firearms.
This ability replaces Throw Anything feat.
Gunsmithing (Ex):
At 1st level, gunsmithing replaces brew potion.
Alchemical Munitions (Ex):
A gunner can use an alchemical item as ammunition in his blunderbuss. Treat this ammunition as a bullet for the purposes of range. Once the item strikes its target, the ammunition is treated as if it were thrown. In addition, the gunner gets to add his Intelligence modifier to the damage being dealt with all firearms. He then gets to add an additional +1 to damage where there would have normally been an addition to the bomb dice pool. All discoveries and extracts that would normally affect a bomb can now affect the ammunition of the blunderbuss (within the limitations of the normal bomb allotment). Example: The Gunner has the discovery Acid Bomb, all damage dealt with the Blunderbuss using standard ammunition deals acid damage and creatures that take a direct hit from an acid shot take an additional 1d6 points of acid damage 1 round later. This is limited by the standard bombs per day formula. So a 2nd level Gunner with an intelligence modifier of +3 can use acid shot (bomb) 5/day.
This ability replaces the Alchemist bomb ability.
Rapid Reload (Ex):
At 2nd level, the gunner is faster at reloading his firearms.
This ability replaces poison use.
Capsule Munitions (Ex):
At 2nd level, through experimenting with various resins the gunner has developed a way to encapsulate elemental damage within a resin bullet. These bullets can be crafted by the normal alchemical or gunsmithing means. The cost of each bullet is 40 gp. He can make these bullets acid, cold, fire, or electric based, and they deal standard gunner firearm damage of that elemental type. These bullets increase the misfire chance by 2.
This ability replaces poison resistance.
Fill the Barrel (Ex):
At level 6, the gunner has realized that he can use the space within his blunderbuss more efficiently. He can now put two alchemical items within the barrel and deploy them at the same time. The additional damage from the Alchemical Munitions ability is still only added once. Example: The gunner loads an alchemist fire and an acid flask into his blunderbuss. He successfully shoots the enemy dealing 1d6 fire (starting the enemy on fire) and 1D6 acid damage + intelligence mod + 3 (being 6th level) plus appropriate splash damage to its neighbors. Half of the additional damage is fire and the other half is acid.
This ability replaces swift poisoning.
Hurtling Blast (Ex):
At 10th level, a gunners knowledge of gunpowder proportions is so accurate that the effects can be increasingly devastating. When a gunner scores a successful critical hit with his blunderbuss (bullet, capsule, alchemical item), the initial attack roll is then applied vs the creatures CMD. From there treat the creature as being bull rushed. Meaning that the target is pushed back 5 feet plus an additional 5 feet for every 5 points that the gunner exceeds the creatures CMD. Example: The Gunner shoots his Blunderbuss at a Succubus and scores a critical hit. Along with the standard critical bonuses to damage, the attack 20 + 7 BAB (level 10) + 3 Dex Mod = 30 is applied vs the Succubus’s CMD (22). The attack succeeding the targets CMD by 8 knocks her back 10 ft.
This ability replaces poison immunity.