A lot of the OT's and conversions from Uberti have that 1871 on the barrel. Wasn't always there, but they added it several years back. Not sure, but I heard it had something to do with a marking requirement for import.
As for the patent dates, I believe the guns were converted at about that time frame and those markings were on some of the originals. Try looking at some pics of originals and I think you will see those.