Frame Size Question
 

I noticed this listing on GunBroker

1030107323

The price listed is way out of line IMHO, but this looks like a relatively high grade pin lifter from about 1874 (haven't looked it up). Only a couple of relevant pictures but it looks to be a 1 frame 12 gauge. Was this very common in that time period?

Usually a gun that early will not have a frame size marking. Guns of that time period do not conform to the later frame sizing system.
I think that the gun was possibly rebarreled or the barrels serviced at a later date. The main clue is that the maker mark appears to be roll stamped. An early gun like this would have a hand engraved legend.