Here's another pic of two incomplete projects: the Asiatam StuG IV and the Torro StuG 111. It just occurred to me that the easiest solution to fitting some sort of gun mechanism to the Asiatam StuG IV kit, would be to cut out the section marked in red from the Torro/HL StuG 111, and fit it to the Asiatam Stug IV upper hull. The upper hull comes with a separate Casemate section, and it would be easy to fit the Torro Casemate in its place as the dimensions, and 95% of the details, are identical.

Careful use of an exacto saw, should enable the extrication of the Casemate, as well as some solvent for the bonded rear panel.
Why would you want to do that? Well, the Asiatam product is difficult, and often nightmarish, to work with (nothing fits quite how it should

).
The StuG IV kit has none of the moulded-in internal studs, stubs, and flanges upper hull/turrets and Casemates have for mounting elevation motors, gun mountings, and so forth. You have to fabricate them yourself.
Secondly, using the StuG 111 casemate from a donor upper hull (only around £25 from Forgebear) means having many of the necessary electrical connections, Airsoft gun (or IR/recoil setup with a Taigen upper hull) fitted in place, and ready to go.....

- Asiatam StuG IV and Torro StuG 111
"Get your facts first, and then you can distort them as much as you please"- Mark Twain.