You indeed do have an Austrian carbine. These were originally made in pill lock, converted to percusson and sold to the Union early in the war. They ended up out in the western theater of the War (Fremont land) and were not well liked. I seem to remember reading that as many as 10,000 were bought, and they sure seem to turn up often. Some of these had poor, soft metal and seem to have worn or broken easily. I think they were made by private contractors, and varied in quality.