Colt 1851 Navy revolver. Possible experimental. Two digit serial number. These are very unusual guns that no one knows for sure exactly what they are. All of these guns have a two digit serial number; some are all matching, some have a mixture of numbers. All of these guns have small frame trigger guards and are US marked. All of these guns have very sharp cylinder addresses and all of them have civilian grips. There have been theories that these guns were made up for the military to prove part interchangeability, these were guns that were sold to merchants like Stokes Kirk that refurbished guns and numbered them to their likings. No one knows exactly what the case may be. Very interesting guns and very rare. We think there are only about 10 in existence.