Hi, Ulrich. V.P.Suglob described in his catalog exactly the model with a 6-digit number, and have ridges on the top. Take a closer look at the photos in his catalogue. But I think, based on my modest knowledge, that in 1957, with the transition from Kiev II/III to Kiev IV, remnants from previous series went into production. It is possible that the serial numbers that year did not have any order or logic at all. I still cannot get a clear answer to these questions. I fully admit that the first Kyiv IV 1957 could have been produced in several varieties in parallel. The 1958 version is sold on the Avito website. As you can see, it also has no stiffeners and a 7-digit number. And these are not isolated cases. I came across both 1958 versions with and without stiffeners
http://www.ussrphoto.com/UserContent2/2522024_1.JPGand 1958 6-digit
http://www.ussrphoto.com/UserContent2/2522024_2.JPGIf there are real photos of the first Kyiv IV 1957 without synchronous contact and with a folding heel like the Kiev II/III, please provide it. I haven't seen one. Until today, I only knew about its existence from Victor’s catalog.
And finally, a riddle. I have already met about ten such specimens. and all were from 195х. What is this? There is no description in any catalogue.
http://www.ussrphoto.com/UserContent2/2522024_4.JPG
http://www.ussrphoto.com/UserContent2/2522024_5.JPG
http://www.ussrphoto.com/UserContent2/2522024_6.JPGBest regards, Denn.