The NO may also have been available in the MC serial number series. Although Mannlicher-Schoenauer production officially ceased in 1968, some examples have been observed with proofmarks indicating 1970 and later as the final year of assembly. For a serious case of confusion, see the Mannlicher-Schoenauer section of the of 1962. The only metric calibers offered to the US market after 1960 are 6.5x54mm, 7x57mm, 6.5x68mm, and 8x68mm.
Therein are listed the 1961-MCA, 1960-MC, 1952-GK, Magnum, and Premier, all have differences. However, unofficially, the 6.5x55mm, 6.5x57mm, 7x64mm and 8x57mm were offered as USA special orders throughout Post War era production. During the M1950-M1952 series production run, Stoegers listed 18 variations of the Mannlicher-Schoenauer in their catalogues. The M1950 NO series was listed by Albrecht Kind as being offered in 6.5x54, 6.5x55, 6.5x57, 6.5x68, 7x57, 7x64, 8x57JS, 8x60S, 8x68, 9.3x62, .243, .244, .270, .280, .308, .30-06. The Model MC appears in catalogues as both 1956-MC, and 1960-MC 15.
Listed for 10 years, that model is number 5 in relative rarity, but, individual calibers will surely take the lead in overall rarity.
Unfortunately, no reliable record has been forthcoming from Steyr to validate the actual numbers thereof.
It is possible that either the M1924 or the NO series included the 9.3x57mm chambering.