So I took the one commercial Croatian mag shooting with about 60 rounds of ammo. Loading up I noticed one thing if you load it with the front feed lip at a downward angle; when you press a round in, the 2nd round down (which would be the one below it on the same side of the mag) gets loose and creeps out a half inch and makes the mag jam up.
Here is a pic for reference -
I shot one full mag, one with 15-20 rounds and the last with the rest (10ish). The first 2 mags went okay but then the last had an FTF when I racked the first round and it had another FTF somewhere in the middle of these 10 rounds. I only I can remember doing differently on the last mag was doing sight picture drills where I would come up from the low-ready position, get a sight picture, fire 2 rounds and go back to low ready.
This would kind of make sense in the light of this issue I had with loading the mags. If the bolt is pushing down ever so slightly on the top round, then the 2nd round down could slip out and help cause the FTF. Whatever the case, with these issues I just dont see these Croatian mags as being a good deal at $12 each when there are Hungarian/Romanian/Polish surplus mags (that are rock solid) in the $10-$15 range.