12-Inch Graphical Firing Table is a table series for many kinds of guns and cannon, M31 is for 155mm M1 gun (also known as “Long Tom”).
circa FEB, 2, 1945
Manual: TM 9-524
Stock Number Reference:
Table, Graphical Firing, M31
Stock No: F1-0088048
M31 12-Inch Graphical Firing Table (WWII era)