About this detail of the Tiger
The main gun of the Tiger was held in a box-like steel cradle. This item is missing from the Hachette kit. In this blogger's photo the area to left of center, with the three large white tubes, is where the cradle should be.
The cradle was bolted to the back of the mantlet. This overall plan of the turret shows the it. The gun could slide backwards through this cradle to absorb recoil forces. The cylinders on each side of the gun tube were the hydraulic recuperator and its fluid reservoir.
A useful diagram is posted at one35th.com showing the cradle in perspective.
This badly-scanned German diagram shows the cradle from above. It has a box shape. The front and rear consist of flat steel plates, 25mm thick, with holes for the gun and the other 2 cylinders.
This is the bottom of the cradle, looking forward. At the bottom of the photo you can see the same 4 large bolts from the diagram. The body of the cradle was formed by a large sleeve (280mm diameter) that surrounded the movable gun barrel, and four thin steel plates that added strength to the structure. The bottom surface consists of the plates combined with the sleeve; refer to the diagram.
The overall structure is easier to see in this photo. Again, we can see the front wall, and relate it to the diagram.
On top of the cradle, there were 3 welded bases, 2 vertical fins and 2 long slots; see the German diagram above. These were all leftovers from earlier versions of the Tiger, when sealing equipment was installed there for underwater travel. They remained there because nobody took the time to erase them from the various factory drawings.
In the Hachette Tiger Tank, the front and rear walls of the cradle are misshapen; the top and bottom surfaces, and the gun sleeve, are missing. Refer to this blog photo. You could improve accuracy by building these parts.