1937 S/42 Mouser Luger

[Bill_in_VA]

I wouldn’t worry too much about serial font size differences, especially on a straight-out shooter. Remember the number stamps did come in various sizes. On a more collectible pistol I’d scrutinize those kinds of things more closely, but I’d be looking for halos (when/where appropriate), over/double stamps, same matching font (e.g., serif/no serif, flattop/round top “3”), etc.