[Radoye]

Where those licence-built MG-17's?

The 109E-3a's have been delivered with MG17's installed. The standard Yugoslav bullet at the time was the same as the German one (7.92mm Mauser) so there were no problems in that regard. As far as i know they used these guns to the end.

Otherwise, Yugoslavs used either Belgian made FN-Brownings or French made Darne machineduns, both chambered for the Mauser bullet. In this configuration Darne had serious problems with jamming so it was being phased out, in favor of the FN gun which was one of the best in the world at the time - same basic construction as the British .303 or the US .30 but much higher quality of manufacture which allowed it to fire at a higher rate and still keep superb reliability.

These FN guns have been fitted to Yugo Hurricanes and other domestically produced types.

Darne was still in use on the biplanes - Hawker Fury and a handful of old Avia 33's that were still around serving as trainers.