The Sigurdian style Bowgun's construction is not complex in any way, nor is it hard to use. It was inspired by the invention of a breach loaded archenbusse, and the rifle-esque design of the stock reflects that imitation. Though slightly more expensive to produce (it requires two bows instead of one) it offers a substantial boost in puncturing power, accuracy and range over contemporary bowguns or arbalests.
The design came about during the reign of King Caelehad II, a Caernian king, who had a love for the arbalest. He notoriously squeezed as many men onto a single castle wall as he could, to put as many bolts in a volley as humanly possible. His personal love for the weapon, was overshadowed by the overarching issue with the way warfare in Caern was being conducted - with Equiux mounted light cavalry that would perform lightning quick bombings at the base of the castle walls. Regular arbalests just didn't have the kick necessary to travel fast enough to either penetrate an oncoming cavalryman's carapace armor. By the time the Cavalry started suffering casualties, the bombs had been set, and the cavalry had began their retreat. He commissioned a team of Coggite engineers to make something with the kick of the much feared "Caernian Tallbow" that wouldn't require years of training to operate. The Bowgun was the result of nearly three years hard work - but it paid off.
The bowgun could easily pierce the armor of oncoming cavalrymen at staggering distances. The result; less Cavalrymen made it to the wall with explosives. Those who did, quickly found that the bowgun had all the pep required to chase down fleeing cavalry, and punch through their armor and flesh. It was a roaring success and Caelehad required that all his castle armories be stocked to the brim with nothing but Bowguns. A slightly unrealistic request, considering the demand for this new item was understandably high.
Like a normal arbalest, it features just four main parts. The Bows, the strings, the stock and the reciever.
Unlike normal arbalests, it features two shortbows mounted vertically as opposed to horizontally. This allows for more men to stand shoulder to shoulder across a castle wall, with more bowguns, firing more bolts into the ranks. The increased bow size allows for greater length and accuracy and better armor penetration. They are calibrated meticulously, so that when the slide releases, both strings are catapulting forward at the same exact rate, so that the bolt flies straight.
The bolts are notably shorter than conventional arbalest bullets and come in two varieties, which are used situationally. One is a shorter, metal version of a standard bolt, complete with fletching, and used much traditionally. The other, known as "Skippers" are also short, but lack fletching. They are made entirely of lightweight wood, both ends being fashioned into points, weighted down by metal tips coated with bees wax. The bolt tumbles in midair, like a spinning pin. This is not accidental - the tumbling bolts emit a buffetting, thrumming sound as they come down in volleys. Psychologically, this is a damaging tactic, used mostly for scattering formations. Making them more deadly is the tendency for the bolts to either skip off shields (as opposed to lodging themselves in it) and hit other targets, either grazing or planting themselves in something appropriately fleshy. Alternatively, the bolt shatters, sending the dangerous metal ends into ears, eyes, throats or noses.
The bows are mounted on either side of the stock, where both strings attach to a slide plate on the reciever. The strings are, in effect drawn at the same time by a crank winch, which is attached to the slide plate and "hammer" which are used to launch the bolt. To draw, the bow is placed to the ground and a foot is inserted through a loop to hold is steady while the user cranks the strings back. When the slide is drawn fully back, it locks into place and a bolt can be inserted into the channel that guides it down the shaft.
Like regular arbalests, there is a trigger attached to the reciever mechanism, which releases the lock on the slide, which will send the bolt flying. Sometimes this trigger is a simply mounted on the bottom of the stock, though the more luxurious models come complete with a carved out handle, a trigger guard and a front mounted stabilizer grip for steadier aim and better accuracy. The kickback is minimal, though slightly more punishing than that of a regular arbalest, not nearly as violent as an Archenbusse.
Compared to traditional arbalests, the Sigurdian Bowgun can penetrate nearly double the armor thanks to the assistance of two bows working in tandem, which offer a boost in kinetic power that approaches two-fold. Punching through standard carapace armor proves to be a fairly simple task for Bowgunner on a wall, at under 75 yards. Most come with an iron sight that illustrates the arc of the bolt, which is slightly less pronounced than that of a typical arbalest. At 80 yards, the bolt begins to drop, which is impressive, considering most contemporary single-shot Arbalests of the highest quality can only put a bolt 55 to 60 yards before dropping, and suffering an even more severe loss of stopping power. There is an exponential loss of power after this arc, and the effective "killing distance" is a maximum of 90 yards for foes wearing light armor. Still better than the contemporary arbalest's 65 yard kill range.
The one issue with Sigurdian style Bowguns is finding someone with the know-how to make one. It's a jealously guarded secret among Caernian and Sigurdian weaponsmiths, who usually don't consider themselves part of the Society of Makers, and thus are under no obligation to share crafting designs. While the demand for these exotic weapons is high on the continent, the manpower required to fill the orders, just doesn't yet exist.