About this detail of the Tiger
It will help to understand the reason for part C-40. It represents a portion of the solid turret wall; but it was made as a separate part to simplify the molding of the kit.
The turret wall is curved, but inside the hole for the escape hatch the German builders milled the wall into a flat surface. The hatch (part C-39) was also flat and so it pressed securely against this surface.
The outer side of C-40 is the flat surface.
When gluing this part into the turret wall, do NOT bend it.
The exposed edge should be thicker in the middle than at the sides.