Anybody know what its for, Its where the navigator (at the very front) would sit.
Put up an image of it please, but if it is anything similar to the situation with the German bombers, biased gaijin tends to “conveniently forget” weapons on iconic aircraft from certain factions. For example on the Ju 88 A-4 (bug report):
I recently went to the library (I live in Sweden) and I looked through history books and articles and found the hole on every plane, Then I saw what looked like a 13,2mm or even 20mm in a mount at the front. multiple sources all over mentions that the B18A & B18B had a 20mm as a armament but there isn’t any photos to prove anything but this just might be it! The plane in the photo is a B18B with a radar hanged on its belly.
Photos of the inside of the Completely restored B18B
Also found something interesting on a T18B.