The model M is the larger of two 9 mm Largo variants of the A/B series of 1911-inspired pistols that led Star design for the next 60 years. The models A, B, P and M had roughly comparable upates over the years.
The model M pistol is essentially the size of the slightly larger model P, and presumably is designed for longer service life or everyday use of heavier loads. Some histories imply this was the original design size, and the A/B size is reduced from this but I have no way to tell.
Pistols marked 9 mm / 38 are designed to fire .38 ACP and 9 mm Largo ammunition, but NEVER .38 Super. Even the model M, with it's extra strength was simply conceived decades before .38 Super or other powerful cartridges existed, so cannot safely fire those cartridges. Read more detail on ammunition for older pistols.
I do not have manuals for every pistol shown on this site. However, in many cases there is a related manual. Partly to make the series relationships clearer, and partly to assist with speed and accuracy of updating, all manuals can be found in one place, the manuals page. All manuals available are provided as downloadable PDFs, or you may purchase a printed copy of the entire set of handgun manuals.
All Classic series pistols strip in the same way. Do not the significant differences between older swinging-link and later "Super" variations.