DCM had surplus Krag ammo available through the 1930s.  Bannerman had a lot of surplus ammo.  Commercial runs of 220 grain FMJ ammo were made in the 1930s.  You could order it from Stoeger or any other big distributor.  Look at any pre-war catalog.

I have only Volume 1 of Hackley, Woodin & Scranton.  It stops in 1939, but makes references to purchases of small lots of commercial Krag ammunition by the military throughout the 1930s.  As soon as I find Volume 2, I'll buy it.