Glock has never advertised magazines to be drop free. NFML magazines were replaced by FML magazines early in the 90's. If your mags came with the pistol, then they are FML magazines. You will never, ever win a long distance magazine ejecting contest with a Glock.
Rear notch on a NFML is shaped like a "U"
Rear notch on a FML is shaped like "\_/"