The conversion is possible...The barrel metal in rim fire barrels are different than center fire barrels (a little softer). You definitely do not want to do this by hand. There is just way too much to ream out. I was thinking of going from a 221 Fire Ball to a 222. I only had to ream the chamber .3" or so deeper (not bigger in diameter) to do it. I was strongly advised not to do it, so I didn't. A 22 Hornet extractor/ejector would work just fine. Of course you have to fit the barrel to a frame, buy the dies and form cases too. May be some case annealing involved, but not sure, because the necks are thin to start with. Just a few things to think about.
