Chinook3,In my experience the term "Flattop" is used to describe the 357 & 44 (non super) up until 1962/1963 when Ruger went to the protected sight version.
The new models above, technically are flattops, but copies of the originals.
JaydaWg
You could be right, I don't know, because I've never taken one apart!!!But JayDawg needs to look a bit closer at the New Models. They use (2) PINS,,,, NOT screws!