were dose the 1917 & the Register Magnum fall under?
Another branch of the Hand Ejector family tree, bigger guns overall, latterly known as the N frame vs .38's K frame.
As I recall without going and getting the book, first came the .44 Hand Ejector First Model, the "Triple Lock."
Some converted to, some made in .455 for WW I British use. They said the shrouded extractor rod was subject to packing with trench mud, so S&W brought out the Second Model without the shroud and without the elaborate three point latch. Also sold commercially in .44 Special.
When the US Army wanted revolvers to supplement 1911 production, S&W devised the half moon clip for .45 ACP, and produced the 1917 in the Second Model pattern. (Colt made .45 ACPs based on the New Service, too. The army called them both M1917s.)
After the war, they continued to make some 1917 Commercials and regular production of .44 Specials.
In 1926 a big distributor special ordered some .44s with extractor rod shrouds, which S&W put in the catalog as the Third Model. They made Second Models alongside for a good while.
The .38-44 Heavy Duty was next, using the big gun to shoot high velocity loads in .38 Special brass. The Outdoorsman has adjustable sights.
They then went hog wild, bringing out the .357 Magnum as a deluxe model. Early ones got you a registration number and certificate, but orders exceeded expectations and they made "non-registered" .357 Magnums until they went over to WWII production. The non-registered guns are actually less common than registered, but that extra number and sheepskin are great selling points, then and now.
Note: A revolver originally sold as a ".32 Military & Police" will nearly always be a .32-20. There are very few .32 S&W Long M&Ps. I think even fewer than the K32 target model, which is itself very scarce and expensive.