Coffenmaker is quite correct,
NOS new old stock does turn up
Its not real common, but
NOS is seen in Auto Parts, Motorcycles and other hardware including Firearms sometimes from the 1920s, 30s.
ASM ceased operation about 2002 was given Life support by AWA to about 2003-4,
** it is not outside the relm of possibility a few survivors exist in someone's safe from a closed old LGS or importer.
I just traded some holster handy work for a Zastava Arms
M57 as NOS
Zastava Arms still makes the M57A Tokarev today. but my milsurp M57 was made in 1981 and never issued or apparently used before it was imported.
Your ASM is a cool survivor,
** AWA was US importer and took on all old stock, perhaps your gun was assembled in the USA by AWA hence no Italian date code,
I had one (AWA) about 28 years ago in 44/40 wish I still had it.