I was hoping someone here could confirm the last year the flat latch cylinder release was used on the New Service.
In about 1932 Colt did a part clean up of old pre-WW1 parts and parts left over from the 1917 military contracts. Many of the assembled revolvers used the flat latches. The so called Civilian 1917s were part of this parts-cleanup. These revolvers were sold for prices below the price of regular commercial model New Service revolvers. This was a way for Colt to use up old parts and sell revolvers in the heart of the Great Depression.I asked a similar question a few years ago. I got several replies. One person indicated that some guns assembled after 1927-28 used left over flat latches.