Apparently, there was no #13. It was to have been printed in the winter of 1945. A few possible reasons for its not being published are WW2 ending, or Fox's trouble with bankruptcy at his company including his printing press company (if he did own it). The cover was printed at Central Printing Company in Pennsylvania, but never used. Information on Fawcett Comics' annual sales of Bulletman from 1941 to the 1946 is taken from the book "Juvenile Delinquency" (from 1950).
CIRCULATION DATA
1941 - 574,794
1942 - 1,544,298
1943 - 245,678
1946 - 680,434