Kynoch 8 x 50R Lebel box

This box of Kynoch 8mm Lebel was still sealed when I received it, but on opening it, I found it to be full of SFM headstamped cartridges. Is it possible Kynoch had this ammmunition made for them, or should I just assume the box was tampered with. It was given to me by a shooter who bought a number of these boxes many years ago, and never got around to shooting this box.

Tampered with, as that box usually contains an " K * 8m/m * " headstamp, and no marking to the bullet tip.

If someone tempered with it, why not to fill it with something really cheap, like 7.62x54R? Was the total weight a consideration? I would not know if I were a buyer at a show.