I just had a look at the RWS/RUAG website and it seems that they still produce the H-Mantel bullet, although the big dealers here don`t offer the 9,3x74R load no more in their catalogues.
I could ask my gunsmith if he can get that ammo and send it to You but I know that it is a problem to send anything to Canada from Germany, mainly because it is not possible to insure the parcel, let alone the old problem with sending ammo.
Besides I believe that the H-Mantel bullet is a rather poor construction, its front part will disintegrate and result in heavy meat destruction. I would rather try to get the rifle regulated with more modern (and cheaper!) bullets.
If You want me to send the ammo to You, feel free to send me a PM.

With best regards

Kalunga