Getting back to the 1944 date- I don't know the reason, but when dating the Beretta post war guns there is generally a roman numeral stamped on the flats. You add that number to 1944 for some reason (unknown to me), to get the mfg date. So my 1961 guns are marked XVII which is 1944+17=1961. Some of the guns of the early 1950's have the actual date stamped like this 1944 on this one, but most have the roman numeral.
Does anyone know why Beretta (and maybe other Italian makers) started with 1944 date?
A second comment I'd make is that Beretta probably had parts available to make guns all through the war. I have a 1948 12ga sxs which is stamped 1948, but the barrels are Beretta marked Krupp Essen and I believe that plant in Germany got leveled by bombs.