Of all shotguns made in Russia, for hunting or clay sports, the easiest ones to answer the “What model is that?” question are the Tula TsKIB over/unders. On most markets they were sold as Vostok, but on some as Baikal (and, of course, there will always be gun dealers for whom every Russian gun is a Baikal). The model name is right on the barrel flats; you don’t even have to remove the barrels to see it – just break the gun open, look at the left side next to the upper edge of the fore-end, and there you have it! There will be the Cyrillic letters МЦ (which some transcribe as MTs, and others as MC, and some even as MU) and the number that follows them is the model number. Here, for instance, you have a MTs 6.
The number that follows the model number after a dash is the submodel code. Knowing it, you may be able to tell whether the gun started out as a hunting, Trap or Skeet gun, had single or double triggers, or came as a two-barrel set. This code varies from model to model; on this gun, MTs 6-12, it coincides with the gun’s gauge – this usually stands for a double trigger hunting version.