They stored G7e aft internal!
KTB Schepke - U-100 - Type VIIb - 2nd War Patrol - Sept. 40
http://www.uboatarchive.net/KTB100-2.htm
Page 11 - 23.15 "Firing tube V G7e relative bearing to target 080°, target speed 8 knots, depth 3 meters, distance 54 seconds."
Page 13 - 0050 "Torpedo fired from tube V, G7e. Relative bearing to target 80°, target speed 8 knots, depth 2 meters, distance 53 seconds."
KTB Metzler - U-69 - 1st Type VIIc - 3rd War Patrol - May to July 41
http://www.uboatarchive.net/KTB69-3.htm
Page 7 - 09.49 "To avoid surprises, gave the steamer a stern shot: Bow left, target angle 90°, depth 2 meters, Eto tube runner ejected with mine gear - Crash dive. Running time 127 seconds - 1900 meters. Hit center." (Eto = Electric torpedo)
Page 8 - 00.36 "Coup de grāce: Stern shot Eto depth 3 meters. Again a tube runner - ejected with the mine gear - running time 30 seconds = 625 meters. Hit center: Steamer sinks immediately."
TypeVIIb and Type VIIc - 1940/1941 - both have performed two stern shots with G7e/Eto