Crossboom? Boombow?

This is a couple of sketches of one of the characters that appears in the short story... he carries a huge crossbow which actually fires explosive shells instead of long, arrow-like bolts, like a grenade launcher. The arms of the crossbow propel the hammer forward so that it strikes the cartridge and ignites the explosive, sending a shell out which then explodes with fiery concussive force. The weapon can hold up to 6 shells at once (yeah, I need to extend the length of the barrel to accomodate this... I haven't done a mechanical drawing of it yet, so the scale is still a bit wonky) and the person weilding it often wears the armored skirt you see here, with 12 pouches that each carry 6 shells, for a total of 72 shells. In addition he carries various tools and replacement parts in pouches along his belt and in his pack, and is capable of manufacturing his own less-powerful (but still very effective) solid-state or scattershot rounds if he re-uses the casings.

The crossbow must be re-armed after every shot, by placing a foot in the stirrup and hauling back on both arms that extend from the sides of the hammer, just behind the cord, until they lock into place. The draw is heavy, but much less than a regular crossbow, and a skilled user can fire and reload very rapidly. Each shell is loaded into a sleeve beneath the barrel of the weapon like a shotgun, and cocking the bow ejects the old casing and loads a new shell.