Given the gun's history you might want to get it "lettered." To do so you send the following to Smith & Wesson:
1. A copy of at least one picture that you posted here. The purpose is to help confirm identification.
2. A copy of your first post, that contains an excellent description.
3. A check in the amount of $30.00, made out to Smith & Wesson.
In exchange their in-house historian, Mr. Roy G. Jinks, will research and examine the old records (which are not computerized - a search isn't always easy) and find where your revolver was logged. A official letter from S&W will follow, that contains a short overview of the model, and then specific information about your gun, usually including but not limited to:
1. The original caliber, barrel length, finish and type of stocks.
2. The date it was shipped, and to what distributor or dealer.
3. Any special features or circumstances that might be listed in their records.
Additional information will be found at:
www.smith-wesson.com
Expect at least 8 to 10 weeks for a reply, as they are getting a lot of requests for this service.
Early on their production was limited, because they were for the most part using pre-war parts. However they did introduce a new and improved hammer block that was developed during the war, and made the gun safer to carry. If you cock the hammer you may notice a square notch in the hammer face, just under the firing pin. That was for the additional safety. I also suspect that the 1948 date is correct, and a letter from Mr. Jinks would confirm this.