Who made it and where it was made is immaterial. There were no NC or CNC machines at the time. There weren’t even milling machines as we know them, (they had been invented, but tech at that time wasn’t conducive to proper end mills like we have now). Milling was done by scraping. The common twist drill wasn’t invented until after the civil war, IIRC. Even on into most of the 20th century, revolvers still required hand fitting and tuning.I would think that that would be a matter of when it was made and who made it?
There quite possibly were some scattered individuals that took the time, effort and money to have an extra cylinder, but it certainly was not common. And besides all that, it’s quicker to slide ready made paper cartridges in each chamber and cap the nipples as it was to pull a tight wedge with a tool, disassemble, replace a cylinder and reassemble.
Most anyone that was in the situation to actually need extra firepower would carry multiples. Keep in mind, there were both civilian pommel holsters and saddle bags with holsters commonly available well into the cartridge era.