Red, that is interesting. The UALR Center for Arkansas studies has a folder of papers that contain a list of the weapons the 8th Missouri turned in by company when they mustered out in the summer of 1865. Each company turned in Union rifles. At the time I didnt think much about it, I'm no CW weapons buff & didnt know what a Union rifle was. In doing a web search today, it seems a Cosmopolitan carbine had "Union Rifle" stamped on its frame, so it was known by that name,as well as 2 or 3 other names.
I could be wrong about the Spencer thing. I had a copy of some document, I assumed it was from the OR but cannot find it in the online edition anyway. Got me to doubting myself.