In his article on the Springfield .22's in the April-July 2001 edition of the U. S. Martial Arms Collector magazine, the late Fred Ewalt said Springfield Armory records indicate that there may have been as few as 30 of the 1922 models converted to M2 with A suffix added to serial number. As I said in my post above, I believe there were many more converted than that.
Model of 1922 serial numbers only went to a little more than 2000. There is no Springfield .22 with serial number 12799 shown in my SRS data.