I should have updated this thread. About 2 weeks later I found out from Colt, that my piece was not one of theirs. Having almost no knowledge in this area, I was trusting the seller. I was able to return it as I did not want a piece, that could not be verified, and may need to be registered. To me it was a lovely piece, but of course looking back all the signs were there that it was a reproduction. Had I posted a picture, I'm sure most would have known it was a reproduction. The seller still has the 1860 Armi San Marco for sale, listed as 38 cal, for a much reduced price. I'm sure it was an honest mistake, probably had no registration paper when brought in.