I just came into posession of a nice Mauser 98 sporter that is chambered in 8x57 but the barrel is pretty crappy and it doesnt shoot very well. I am considering chambering it in 9.3x62. How would I go about filing the box magazine to properly open it up to the proper length? Also, who has a reamer in this caliber?

I believe that the 9.3x62 was designed to fit in a standard military 98 magazine without alterations. If you plan on using longer than normal bullets, such as Barnes X 286 gr, than a commercial .30-06 length magazine would give you a little extra room.

I HAVE AN ORIGINAL OBERNDORF I 9.3 I,LL TAKE A MEASUREMENT LATER AND POST THE DIFFERENCE I DONT THINK IT IS MUCH PAUL