I found this box at a gunshow this weekend. FN 52 head stamps. This is the second box of FN ammo I've seen from the 50s, the other one was for a Bren gun, it said on the box. Would this have been for practice, or is this the rubber bullet they talked about being used in NI? I have some Czech plastic core ammo with a copper jacket that I heard was for training, but can't find any definnate info on it so I'm not sure if any of this was really for training.