A lot of Engish DG rifles had shorter lengths of pull than what WE "now" consider normal or like.
Remember, people were smaller, shorter and lighter in those days than they are now.
500, what is an average or common lop on a double of the 1900-1939 era?
Many Original Mausers and HVA Mausers of the 1900-1939 era had lop's hovering around or slightly longer than 14", actually longer than common factory rifles today.