It sounds like you have a Colt Army & Navy revolver. It was the first DA, swing-out cylinder revolver adopted for U.S. military service, originally by the Navy in 1899 and then later by the Army. There were a number of changes and each had a different Model year. They are very difficult to work on and finding a qualified armorer has become almost impossible. Parts are equally difficult to find. The design was flawed and led to major changes in Colt DA revolvers.

It's .38LC cartridge was seriously questioned by the Army during the Philippine-USA War and led to the emergency call for a .45 revolver which resulted in the Colt M1909 which was in service for only 3 years when the Colt .45 M1911 was adopted.