But as I saw in my first post, I made a small error.
I wrote "now" instead of "no" in the part of the build-feature.
Sorry for that mistake!
For me this was only one forgotten letter, but for the english-language-speakers these are very different words; and in this case, these also will fit into the text.
At that time, I got no answer for my written text and possible corrections or additions of my (completed) build-feature.
Also some useable photos (of my first diorama) were collected for this, but not sent.
But I will use this build of the "same gun" as a comparison-build, as I did it with the barrel.

Also some other parts are a bit different to Trumpeterīs kit.
Both are very good and have nice details, but Dragonīs kit looks "finer detailed".
A combination of the parts of both companies (using the machines by one company) will give a great kit and easy to build kit, I think!
For the difference of the 2 barrels and its parts, Trumpeter made one sprue, consisting of 2 separate sprues for the different parts of both breeches and parts.
(I have a good photo of this)
Also Trumpeter removed the un-needed sprue for each kit, but has an plastic and metal-version of the barrel.
Dragon made an additional sprue for the new parts, which also looks good.
So I have 2 breech-parts, to compare 15cm and 10cm.
Also Dragon has only a metal-version of the barrel, but no plastic-version.
But the metal-barrel looks very good and seems to be correct in length.
As I mentioned, Dragonīs barrel has a finer rifeling, which also is "turned". Looks great!
Ahh, the bigger brother (Dragonīs s.Fh.18 kit) has no rifeling, so this is a great progress... also for the smaller calibre!
thats all for today...
Soeren