I read, many years ago, of someone who used drill bits to rechamber one to .30-06. He drilled out the neck area large enough to take the .30-06 neck and bullet, but left the bore the original 6.5.
Supposedly, the action held, although it swaged the .30 caliber bullet down to 6.5. He did write that the recoil was brutal. Actually, the subject of his letter was why it kicked so much.
