About this detail of the Tiger
The Hachette Tiger Tank model provides the gun, and a protective bar on the right side of the breech. In this blog photo you can see these parts. The breech has a circular item on its right side, and the bar makes a detour around it (at the lower left of the photo).
In this photo of a real Tiger, you can see the protective bar [1] does not curve in such a tight circle as in Hachette's model. The photo was taken from below, but it's clear that the bar slants upwards at the front, with no sharp corner.
Another feature in the photo is the breech release lever [2]. This is completely missing from the kit. But it is the reason for the curve in the protective bar.
This detail from a French diagram shows the breech and its lever. The lever opened and closed the breech block itself.
You can improve the accuracy of your Hachette Tiger Tank kit by modifying this area of the gun.