Here is a find. Both full sized and scale models - Pinterest: 8 sections:1,188 pins: 90 followers
Krajina Express (2) ,Japan (4), UK (12), US (3), France (14), Germany (435), Poland (39) , Soviet (157),
I don't know where they arrived at their number. The quantities shown above come to 666. The site is certainly behind Railway guns, but some of the pix are new to my eyes.
And thank to our colleague, Alamo, for the info on the K5 scale models.