
According to the survivors of the U 453 it is specified that in the patrols 7th and 8th she had a new configuration namely, deck gun of 88 and the "Mittelmeerturm" that was turm 0 but elongated to carry two Breda twin machine guns of 13.2 mm (one pair to each band) and to the rear the machine gun of 20 mm C / 30. The Breda machine guns were retractable and were stowed in airtight containers located in the bands of the platform.
As far as I know these platforms were placed in La Spezia from the summer of 1942 to the submersibles that operated in the Mediterranean. According to the history of the submersible I think that this modification was carried out at the end of the 6th patrol when the U 453 moored in La Spezia on October 15, 1942, but I am risking, does anyone have an exact date?
Source: https://historisches-marinearchiv.de/pr ... var2=wert2
http://www.uboatarchive.net/U-453INT.htm
Von Original zum Modell - U Boot Typ VII.
Cheers. Raúl M
