See if you can track down a copy of "The World of Beretta", by
R.L. Wilson, Random House, NY, 2000.
There is some information within on the 403 Stella.
Apparantly the "Stella" first showed up as the Model 3 Tipo Stella c. 1926, by 1934 it became the Model 103 and post WWII, or at least by 1947, it was known as the Model 403 Stella and
carried in the Beretta catalogues until 1958. It was originally available in 12, 16, 20, 24, 28 and 32 gauge through 1950,but by 1950 was 12, 16, 20 & 28 ga. only and by 1956 in just 12 and 16 ga. A reasonably high-grade hammer field gun with "Special alloy steel - Titania" barrels.
Beretta apparently did not specifically list "competiton/target" guns during this period, other than those devoted to live pigeon shooting. In 1949, the Model 404 Piccione & 405 Piccione Extra hammer guns were available for that sport.