Originally Posted by Bruce M
I paged through the Standard Catalog of Smith and Wesson last night and did not see anything regarding the ampersand change. My guess is that it might be different for the pistol slide than for revolver barrels and my other guess is that whenever the change was made might not be the most accurate dating method. Especially in that time it seems as if Smith and Wesson may have had substantial stocks of some parts that got stacked up somewhere and not used right away. My guess is that we still see the results of that over the last decade or so when they suddenly reintroduce some discontinued version for a small run.
They probably changed it, but still had many parts in stock of the old style. Like I said, the only other Smith I own with it is my 1955 Target Masterpiece.
You can see it clearly here. Its the only Smith revolver I own with it.