B.Dudley,
It wasn't mentioned above,but your rifle was proofed in Germany,not in Belgium.Based on this,and your description, your rifle was likely to have been built in Germany,as well.Rifles like this are often made on M88 actions, and by 1933,surplus M98 actions were readily avaliable.How sure are you that yours is an 89 Belgian action. American made 8mm Mauser ammo(Rem.,etc.)is perfectly useable in your rifle.
Mike