its really sounding like you havent owned guns that long at all. the 2 holes in the top were for a scope mount. there are likely 2 others further back on the reciever.
could you see the casing through the origonal 2 holes ? if so then it was pretty screwed from the getgo. but those 2 smaller holes would have been slightly more repairable but not 100%. this 1 big CM hole is straight through into the barrel (its into the chamber) your likely looking at way to much money to repair it for what the gun is worth. (as it sounds like its just a sporterized mouser 98) if of course you could find a gunsmith willing to try and fix it.
could you see the casing through the origonal 2 holes ? if so then it was pretty screwed from the getgo. but those 2 smaller holes would have been slightly more repairable but not 100%. this 1 big CM hole is straight through into the barrel (its into the chamber) your likely looking at way to much money to repair it for what the gun is worth. (as it sounds like its just a sporterized mouser 98) if of course you could find a gunsmith willing to try and fix it.