First Model B
The first Model B is fundamentally the 9 mm Luger/Parabellum version of a similar 1922 and first and second Model A pistols. These are transitional guns, with broadly the control layout of the Colt/Browing guns (epitomized by the 1911), but based on the overall layout of the previous series of Star pistols.
The Model B was developed and marketed synchronously with the Largo versions, with production commencing in 1924. The model ceased production in 1931, when it was replaced with the Second Model B, below. This first Model B has a smaller safety lever than later guns, a T-shaped extractor, a large lanyard ring on the left side, a flat backstrap and numerous detail differences from the later, more refined guns.
Only a few seem to have been made, apparently mostly or entirely for export sales.
Second Model B
In 1931, production shifted entirely to this updated version which added several, mostly external,features to make the pistol look and handle more like the Colt 1911A1. The frame was changed to provide an arched backstrap and a larger safety as well as more rugged and higher-visibility sights were fitted. Numerous small changes were implemented across the design, from a shortening of the barrel bushing, to elimination of the separate safety guide bar.
Large numbers of these guns were produced. The image at the top of the page is a typical European commercial model with wood stocks and blue finish. Many variations of finish, stocks and sights were produced. This basic model B remained in production continuously until 1983.
Made from 1946 to the end of classic-model production in 1983, Model Bs with Super upgrades were produced. The major change is the replacement of the swinging link with a Sig 210 (or modern Star) style closed cam path integral to the barrel. Related to this, a full-length guide rod with captive spring, and a quick takedown lever were added as well. All of these models have a magazine safety, but one slightly different from the later S variants, and the extractor is modified to double as a loaded-chamber indicator. Additionally, the sights are improved in shape to make them easier to see, and minor changes were made to the trigger system.
The model BS is a normal, second Model B, except with the addition of a magazine safety, made for individuals, locales and agencies which require one. It was produced from 1957 to the end of classic series production in 1983.
The Model BG is supposedly a small change to the magazine latch; only about 2,000 were made, in 1965 and '66.
Compact Models BKS/Starlite, BKM & BM
The BM, BKS and BKM are shortened, compact versions of the basic Model B pistols. None were made in the "Super" configuration with the linkless barrel.
The BM is steel while the BKS and BKM are alloy framed. The BM and BKM have the same dimensions, and are noticably smaller than the slightly earlier BKS (see the comparison diagrams below). The BKS was also sold in the US under the Starlite name. This is presumably because it was unusual at that time to have an alloy frame, so the light weight was of note. The BKS, at least, had a magazine safety as on the BS.