I have recently acquired a family handgun, which happens to be a 1942 Beretta 7.65 mm. I had a friend research the model, but there is a small, almost unidentifiable “M” hand-engraved on the left side of the thumb guard. My knowledge of gun history is quite limited, so I was wondering if anybody here could help me?
Your topic will soon be moved to General WW2 Discussion. I wish I knew the answer to your question but sorry I dont. 
Edited: Meant to say Gen WW2 Dis.
Post some photos, and I’ll look it up for you. The hand-engraved M is likely to have been done by the officer/specialist who was issued it.