The Carcano 38 rifles of WWII vintage carried a two-letter prefix to the S/N. Later in the war all other manufacturer markings were omitted. My Moschetto 38 is dated 9/42 and carries S/N TW2xx but no manufacturer marks. The TW prefix means the Royal Arms Factory at Gardone Val Trompia. Perhaps the 2 letter codes on MAB38/42s and 44s without the manufacturer's name are equally significant. My MAB38/42 is marked "CS" but that code does not appear in the Carcano listings that I have seen so there is probably a second list somewhere