Savage produced over 1 million No4s during WW2. even working 24/7 from the 1st Jan 1941 to 31 Dec 1945 (5 full years) they would have to produce over 3,800 per week, so 1L4072 to 1L 6926 is less than a week of production, they would have used more than a single production line to serialize the rifles & they would have been allocated blocks of serial numbers, the rifle would not have been leaving the end of the line in a numerical order.