There were / are no "1950/52 MCA Models" of Mannliucher Schoenauer rifles or carbines. MCA was introduced after the models of M1950, M1952.
Stoeger had declared themselves to be 'sole importers' (to the U.S.) of Steyr products since the late 1920s.
Side safeties were factory installed in postwar models.
The first four models of MS sporting rifles and carbines were not in "early safari calibers", they were each dedicated to their own MS proprietary cartridge. The prototype M1900 and Military ('Greek') Y1903 (and all variants) were in the new MS6.5X54 cartridge, as would be all M1903. All M1905 were 9X56MS, M1908 were 8X56MS, M1910 were 9.5X57MS - known to the Brits as .375 Nitro Express Rimless.
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Model M1924 was introduced as the 'Sequoia', originally distributed only by Sequoia Importing Company of San Francisco and Detroit.
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Model M1924 was built on a longer receiver to accommodate the 'U.S.Cartridge of 1906' (.30-'06) and all were so chambered. Production continued on the same 'action' in a variety of chamberings on rifles and full stocked carbines (Stutzen) through the early years of Anschluss (Nazi occupation of Austria). These were marketed by Stoeger as 'High Velocity' and are now referred to by collectors as 'M1925'.
Eventually production ceased (early 1940s) until introduction of the M1950.
MC and MCA styles came after the M1950 and M1952, and with their introduction buyers were advised to order the M1952 if they did not wand an MC or MCA style stock.
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The designations MC and MCA were "Monte Carlo" and "Monte Carlo Amerikanische" or "Monte Carlo All Purpose".
Model MC:
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Model MCA:
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Models M1950, M1952. The M1952, or 'GK', had a swept back bolt handle, retained the straight comb stock of previous models.
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From 1925 onward, the Mannlicher Schoenauer 'High Velocity' (now referred to by collectors as 'M1925') was offered by Steyr in a variety of chamberings, many retailed to the U.S. through Stoeger. Here are 1939 offerings:
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Much of the reason that "Mannlichers are valuable", for the MS, has to do with the same factors that made them highly desirable when new and still so highly regarded; they were finely crafted, supremely balanced, had stocks shaped for instinctive 'pointability' that was / is unparalleled for 'snap shooting', they absolutely never jam when fed with proper fitting cartridges, the smoothness of action is superior to all others... .
If you have never had the experience of handling / shooting a Mannlicher Schoenauer I'd highly recommend that you do. They are far more than just a 'name' or style of (stutzen) stock.
What basis have you for the assertion that "Their safety is a bit low grade too. [sic]"?