I figured some of you guys might find this interesting.
Here is the skinny on chrome lined barrels in Yugo weapons including of course sks.
I wrote to Mr.Branko Bogdanovic , asking him what was the reason why Yugo sks were chromeless.
For those that don’t know who he is, Branko is THE leading authority on all Yugoslavian weapons, and also Kragujevac factory historian. Of course, Kragujevac is the one and only Yugo factory that produced small arms in Yugo.
The technology for producing chrome and nickel existed in Slovenia’s steel mills ( one of the former Yugo republics, now independent state) in 1950.
But, technology of actually applying hard chrome in barrels, began after1970 in Kragujevac factory.
First chrome barrels were produced in M70 automatic rifles ( Yugo Kalashnikovs), and Yugo automatic pistols Skorpion 7.62 mm M84 ( Czech scorpion M61)
So, in short, Yugo had/has plenty of chrome, the know how just came late, after 1970.
It has nothing to do with Russians, cost prohibitive, or else.
My correspondence with Branko was in Yugo language, I did my best to translate.
I hope you find this interesting