Mauser98
You shoul have commercial Mauser98's you must be carefull when ordering a replacement ones their are lots aff subtle differences between the 3 major sizes. Their is a large ring, short ring and ugoslavian mauser it is the same length as the small ring but the diameter off the large ring. I am fairly sure the large ring is the model you have call numerick as stated above or Mitchells Mausers there in the US have the rifle with you the two measurements you need are the distnce between the takedown screws and the width off the front off the action.
Cheers Bill
Australia