Lots of the older models had "names" before they had model numbers.
Well, kinda.
S&W's initial tip-up SA revolvers had model numbers. The first two original models were the Model No. 1 (5-shot .22 Short) and the Model No. 2 (6-shot .32 rimfire). Some time later, they decided to introduce a smaller 5-shot .32 model but wanted to continue numbering models in order of increasing frame size, so the new gun got a rather entertaining designation- the Model 1½, often spelled out One-and-a-Half.
When S&W retired the tip-ups and introduced centerfire top-breaks, the new SA 5-shot .32-caliber revolver was designated as the New Model 1½; the relatively unpopular 5-shot .22 and 6-shot .32 models were dropped. The company introduced a SA large-caliber model and designated it as the Model No. 3. However, they also introduced numerous double-action top-breaks during this time period, and these guns were given names rather than model numbers (e.g. .38 Safety Hammerless). The DA guns were soon outselling the SA models by huge margins.
When S&W started introducing swing-out cylinder revolvers and dropping the top-breaks ca. 1900, the swing-out models were also named. As the SA top-break models were dropped, the model numbers disappeared with them. Initial swing-out cylinder guns were named rather than model numbered, which causes all sorts of confusion among novices because S&W only marked
two of these guns with the name- the .38 Regulation Police and the Highway Patrolman (.357Mag large frame). The model names were shown on the boxes, catalogs, and owner's manuals, but most of this stuff was thrown away or lost by prior owners many decades ago. These guns must usually be distinguished by correlating the chambering, frame size, and sometimes the type of rear sight (e.g. .38Spl + 6-shot + K frame + adjustable rear sight = .38 Military & Police Target).
In 1957, S&W started using the present model-numbering system and marking guns inside the yoke cut. When the system started, the numbers 10-19 were assigned to K frames, 20-29 to N frames, 30-38 to I or J frames (all I frames were later replaced by J frames), and the number 39 was assigned to the 9mm DA/SA semi-automatic pistol.
Subsequent models were assigned model numbers in a haphazard semi-consecutive fashion. 60 thru 69 have SS finish, but for the most part, 40-59 are a mess.