Just purchased Sub 2000 that takes Glock 19 mag, from TargetSportsUSA. FFL opened up box in front of me, 15 round mag, yes, but its a PMAG, not a Glock. Is this normal, or did someone pull a switch on me, or....?

has anyone tried to fit the PMAG D-60 onto a Kel-Tec RDB? does it fit? I feel like even if it did fit there would be some rubbing of the hand against the drum. If anyone has tried this let me know your experience and if it is practical or not.