Citizens Of Antiford Bolt Actions and revolvers can be considered common in Orr as well as an abundance of lever-action rifles and pump shotguns in Araz. These forms of semi automation have forever changed combat in the world.
However guns employing Blow Forward, Blowback, or gas operated automation is extremely rare. Gas operation for semi or fully automatic fire is under research and has not been perfected. Any weapon utilizing any of these methods would be considered experimental, expensive, and rare. Usually they are not worth the trouble.
For more information on automatic weapons on Orr please check out Steam Powered Weapons.