Having chrome ore is not necessarily having production capabilities. From those and other CIA reports, it appears that Yugoslavia used its mineral wealth to gather foreign exchange and its production capabilities took time to rebuild.
"War and Revolution in Yugoslavia 1941-45" By Jozo Tomasevich p. 640 "The same sources reveal that chrome ore mines such as the Jezerina Mine in Macedonia, were almost completely exhausted by the Germans." You find the same thing reported in "A Low, Dishonest Decade: The Great Powers, Eastern Europe and the Economic Origins of WWII" which shows pre WWII chrome production by Paul N. Hehn.
Weaponsman blog has a review of chrome plating and rifles that is pretty good but simply mentions that Yugoslavia did not chrome plate the bores.
http://weaponsman.com/?p=12779
This is from an akfiles forum posting about Yugo chromed bores allegedly from a former Yugoslavian poster: Zdeno
"Three factors.
1.) Price, the price was the major culprit in why the Yugo's never chrome lined, it was cheaper and less time consuming just to use steel, less time spent paying people to manufacture meant there was more money in the Federations coffers.
2.) Preservation and conservation, here in Serbia we generally attempt to conserve the resources we have by importing, unless it's a dire situation or an emergency we usually run on the bare minimum required to do anything. This dates back to the 70's if I'm not mistaken.
Importing chrome would have been too expensive and nobody wanted to use ours at the time, so nobody bothered.
3.) They just didn't see the point, nobody got why chrome lining was so insanely popular, in a fully automatic rifle it makes little to no difference other than in the maintenance and cleaning of said weapon, you may or may not get more service life out of the rifle with chrome lining. Apparently, nobody wanted to waste time in finding out when what we had was working well enough for us to begin with.
In a civilian rifle it makes a difference, in a military rifle it doesn't really mean anything at all.
Would you waste money on something just because it's more shiny than what you have but it works and does the exact same thing?
It would have been a waste of resources, money and time, three things the Yugoslav's never wanted to spare."
http://www.akfiles.com/forums/archive/index.php/t-103548.html
And here is a second hand forum posting from someone on SKS boards asking Branko Bogdanovic that very question:
"In response to this topic, I chose to start new one so everyone can see, and hopefully remember for future references.
http://www.sksboards.com/smf/index.php?topic=25410.0
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.
His response:
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
Best regards
Dan "
From the following several CIA reports on Yugoslavia in the 1950's. One indicates postwar increases in production of chrome, however, they note that it was not sufficient to meet domestic demand and as a result some was imported, a 1986 report, indicated like the 1950 report that the need for foreign currency due to deficit in payments led Yugoslavia to export minerals including chrome rather than keeping it at home. A 1952 report to the president regarding strategic minerals indicates that Yugoslavia's chrome ore is of lower quality.
Thus, when Yugoslavia first produced the SKS, chromium and ores were more valuable as a foreign exchange source and apparently at least from the other CIA reports, in the early 1950's, indicate that Yugoslavia's domestic demand was not met at that time by domestic production. Later, why change to chrome lined bores if the SKS non-chromed bores worked good enough and by the end of their SKS production, much was for war reserves and export so not much reason to chrome the bores then. In addition, from Branko's posting, he indicated that Yugoslavia was late in developing the technology of chroming bores.
Like most things, it is probably a mix of reasons,