Here is my Colt Model 1861 serial number 37544. According to the author of the latest Colt Model 1851 and 1861 book, Bob Jordan who was allowed access to Colt factory records, this one was made in the early 1870s. This exact number not recorded but others in the range were being produced about then. Well into the time that the Single Action was being worked up.
This is the other side of Colt Model 1861, serial number 37544.
The book that I am referring to is Colt 1851 and 1861 Navies and Conversions by Robert M. Jordan and Don W. Geri, published last year. The price is $250 plus shipping. To buy it, the author can be reached at [email protected]. Yes, it sounds expensive but you will learn things that will make the cost more than worthwhile. The Nathan Swayze book was good for its time, but this one will be the final definitive work on this subject.