As Conder mentioned, there are two different reverse varieties for this date. The variety 1-B is apparently rarer, and appears to match what you have posted. Here is one in the Heritage archives, and the mintmarks appear to match the OP coin. https://coins.ha.com/itm/liberty-ha...2-3783.s?ic4=ListView-ShortDescription-071515 I don't see anything immediately alarming about the OP's coin, but this is a very rare coin and worth a lot of money. I really have to wonder why it has not been authenticated, if it is genuine. A few estimates seem to indicate that there are only about 150-200 examples of 1871 CC $5 in existence.