The letter O is missed out because of a possible confusion with zero, while Q also leads to confusion when stamped very small. The reason is that the Italian language does not use the full alphabet – J,K,W,X and Y are not used in Italian words. You may wonder why the letter sequence is not logical. Here's the list - and apologies for a rather long post: The first Beretta firearm using this dating system was the Model 1934 pistol (introduced in 1935).
Italian guns are easily dated by a code - not in the serial numbers but next to the proof mark. This practice ended in 1945 with XXIII at the close of World War Two and the chart below takes up from that point.
