The good news, tayous1, is that any Beretta SMG mag will work in the Modelo 38 family of SMGs!
So even the mags for the modern P12 and P12S will work in that Beretta 38/42.
The Beretta 38/42 was a very popular weapon with German forces in Italy. They favored it over either of the so-called 'Schmeisser' MPs!
After Sept., 1943, and the Italian surrender, the Germans continued making 38/42s at the same factory, but instead of being marked BM 38/42, they were marked MP 38/42. There was also a MP 38/44 that was manufactured right up to about 1950, that didn't have the fluted barrel and had a shorter, simpler bolt.
It was also one of the favorite GI 'bring back' weapons from WWII.
Magazines have always been relatively rare due to the Italians' habit of throwing away or damaging their weapons' magazines prior to surrendering.
BTW, the German Army issued MP 38/42, 38/44, and the final model, which IIRC, was called the Model 5, right up until 1969!
MG of The World calls it one of the best SMGs from WWII.
Eric The(MyGreatUncleHasOne!HeWasInItaly!)Hun[>]:)]