Michel,
This is a good solid foundation for your AAA guns ! This is perfection and the first thing that jumps out at me is just how nice the circle cut is on the upper portion. I have tried to cut similar sized circular holes in wood before, and it is not very easy to do unless you have access to a milling machine.

It also matches up nicely with the pictures you posted earlier.

Well done my friend. Very well done indeed.

I worked the base further, so did I with the gun assembly. Pictures on the gun will follow tomorrow; I'll take them in daylight.

The concrete texture was achieved by covering the sanded model in blackboard paint from the rattle can (black color, of course). I then pre-shaded a bit using white colored primer. After that set, I mixed some grey and white acrylics to obtain a light grey concrete finish. I applied a light coat to let the dark and white shading come through.

Happy modeling!

Absolutely like the concrete effect, Michel @michel-verschuere
Looking forward to the pictures of the Flak.

Great progress, wonderful research and looking fantastic! Cannot wait to see it completed.

@gwskat @lgardner thanks for checking in. Regarding the boresighting, these weapons had enough velocity to take the 26kg shell to 30.000 ft (10 km) height. I think they were installed completely parallel. The inter distance was about 2m and there are few manned aircraft - especially bombers - that have a smaller cross section. The guidance of the gun was electric, via an analog computer. The signal changed the deflection and azimuth and also the fuse timer. The convergence of the gun was not one of the settings. In dogfights - that usually happen within a couple of hundred meters - this is different of course and aircraft as you mentioned had their guns converging to a point ahead of the aircraft by a few hundred meters.

The main reason why the Flak 40 128mm gun evolved from single barrel to twin barrel versions such as these is the firing rate that roughly doubled on a twin. These heavy guns were almost exclusively installed on Flak towers near or in industrial centers or major cities (Hamburg, Berlin and Vienna had them). The advantage being that these were the targets of bomber formations and therefore the gunnery could be more accurate because deflection and azimuth were quite stable during the final bomb run as opposed to fly-by situations for Flak gunners. With double the firing rate compared to the single barrel Flak 40 these twins almost doubled the hit probability to up to 25% maximum.

Thanks for your words folks!

Good idea to use metal instead of plastic for the barrels, Michel @michel-verschuere
They look much more realistic in this way.
Great progress.

Since I decided to use metal barrels, the mechanism offered with the kit enabling the guns to be elevated is too weak. The kit parts consist of two little gears that are to be assembled onto an axle with an inner joint. It would be virtually impossible for this weak plastic joint to withstand the torque of the slanted barrels, especially not at lower elevations. I therefore engineered this part and drilled holes to enable a brass tube to be inserted, forming a strong core that does not easily bend.

Here are some pictures. I will now turn toward the final assembly but must see what parts can be glued already so that the individual barrels and breach assemblies can still be disassembled for the painting. I also used a small Eduard PE set to detail the control boxes, you can also see that in the picture.

Hope all is well with you guys!

Some really serious modelling, Michel @michel-verschuere
This will be an awesome Flak.