Lets go back to school. N frames started real low, probably with a number 1 gun back about 1907 on a triple lock. Those numbers went up to somewhere in the 62000s at the start of WWII. After the war, the number sequence picked up pretty much were it left off, except it had and "S" prefix. Yes, the GCA was the moving force behind the "N" prefix as each gun had to have a unique serial number.
At times in the past, there was probably N, K, and I frame guns with the same serial numbers between 1 and about 62000. The I and K frame guns came decades earlier than the N at 62,000+. Its why someone running a gun through NCIC needs the model and caliber, as well as the maker. Get the maker wrong and you might have a stolen Colt or Winchester that has S&W on the frame!!