About this detail of the Tiger
The Tiger's gun had a hydraulic recoil system, comprising two large cylinders stored either side of the gun. The rear end of each cylinder was attached to the breech block.
This German diagram shows the bare breech block from behind. It has protrusions on each side where the cylinders attach. Dimensions are written on the original diagram.
This is the right-hand side of the breech (the green paint is not original). You can see the end of the cylinder slotted into place. It was easily removed for maintenance.
Another view of the same gun. The cylinder is blackened where lubricant leaks out. The part to the left of this area, moves back when the gun fires; the rest is fixed to the cradle.
In Hachette's kit, the moving rod is placed off-center. But if you examine these photos, you'll see that the rod was exactly centered in this cylinder. You could improve the kit by moving this part, and adding the protrusion on the side of the breech.
On the left side of the gun, the protective shield hides the moving part of the cylinder. But we can see the fixed part and its valves, thanks to an opening in the guard shield. This opening ends just about where the square corner of the breech block begins. In Hachette's kit, this opening is too long.
You can improve the Hachette Tiger Tank's accuracy by rebuilding the attachment of the recoil cylinders.