I might be off there.

(not so schocked)
I was repeating what "they" told us in the academy. I know Branko spent a LOT of time researching this subject (I never did). Why was the Communist government "fudging" the dates, can only be speculated on.
Maybe because 1948 was a very important year in the Communist history? 1948 was the year they broke all ties with Stalin's Russia (infamous Informbiro), arrested (and imprisoned) MANY Russian sympathizers, and told us that the rifle was produced (and adopted into JNA) that same year.
FYI,.....I was born in 1955, entered the academy in 1975 (switched from the "regular university"), and by then this was already in the history books. History "they" wanted to tell, for whatever political agenda at the time. I left YU while they were still in power, and MANY actual truths came to surface once the Communist government fell. So Branko had the benefit of opening of the national achives, and researching through the actual data. I was an officer, and fed the oficial line at that time.
They trained us as elementary school students on M48 (I live fired it for the first time in 1968), and later for two years in the high school (ONO - Opce Narodna Obrana). Once in the academy, M48s were not seen again (by me) in training. Academy training started with M59/66, went on to M70 series, M72, M53, M57, RPG, mortar, recoiless, mines, booby traps, anti armor, parashooting (static, free, HALO), etc.
Next time I encounterd M48, was in Kosovo in 1982 where some Iredenta Muslims used them against us, but in small numbers. They mostly used Italian and British submachineguns. Fast forward few years, and they (M48s) appeared in Bosnia (not so much in Croatia) in the wars of the breakup.
I am sure that if this government survives to govern the next generation (US), the kids will be thought in schools that Sadam had WMDs, and that's why we went to war with Iraq. They (regardles of the ideology behind them) all operate on the same proven principles,....lies and deception, to keep themselves in power, and to justify their actions.
So I apologize if I unknowingly perpetuated Communist propaganda on this forum.