Bow Gun, heavy (3.5e Equipment)
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A bowgun is a technological marvel, developed as a colaboration between the expert dwarf weaponsmiths Tundlewar Badgerbeater and gnome engineer and alchemist, Roary Bodwingle. This weapon is in many ways similar to a repeating crossbow, although it is made mainly out of steel. The bow gun is loaded from the bottom with a magazine - similar to modern firearms - which holds 10 specially-designed bolts. However, a major differnce between the bow gun and a standard crossbow, is that as the bowstring is released, it strikes a flint, which causes a spark, wich then in turn ignites an alchemical substance in the base of the bolt, causing it to be propelled forward like a modern bullet.
A heavy bow gun can be fired one handed at a -4 penalty on attack rolls. You can shoot and load (due to it's automatic reloading, see below) a heavy bow gun with each hand, but you take a penalty on attack rolls as if attacking with two one-handed weapons. This penalty is cumulative with the penalty for firing one handed.
Due to a contraption of springs held within the body of the bow gun (similar to the bolt from a modern firearm), it automatically reloads after each time it's fired as long as there is still a bolt within the magazine. This means a full-attack action can be taken, allowing you to attack with a bow gun as man times as your base attack bonus would allow.
It requires a full-round action which provokes an attack of oportunity to load a new magazine of bolts into a heavy bow gun, although a character with the Rapid Reload feat can do so as a move action. A case of 10 bolts for a heavy bow gun costs 50gp, due to the alchemical substances required for each bolt.