Yes they are interchangeable. I was looking into this before i brought my IHZ18MH but it seems that this can only be done at the factory when you order a new rifle or though a company that would just buy the barrels in bulk.
The importer of Baikal in Australia told that they would not do it at all and bluntly told me to just buy two in different calibers and his words where “they’re cheap enough”.
I talked to a independent importer of Russian firearms who told me that Baikal will except orders of just barrels with a unit number starting at 200 and also why the other importer stated that it could not be done because they buy the firearms from a third person “a European wholesaler”. I dont know if that last bit is true or not about the purchasing from a third person, i have been told by a mate of mine that works at the local gun store that the rep assured him that they buy direct.
I ended up buying one in .308 and next year i will be looking around for a second hand one in .223, keep the stock as a spare or just play around with the action.
I have read i interesting article (
http://forums.nitroexpress.com/showflat.php?Cat=0&Board=single&Number=72033&Searchpage=1&Main=71583&Words=BAIKAL&topic=&Search=true#Post72033) that told about a person buying a Baikal s/s shotgun and using the monoblock off it make a barrel for his IHZ18 in a different caliber.
