If you search the web on hammer forged barrels, there are a couple of articles, lost the bookmark, but found it again. This talks about how Ruger makes these barrels:
http://www.vsms.org/Forum/Seite_34_forget-barrels/S34.htm
Did not read again, but here are stresses created when barrels are hammer forged. If you cut away material from the outside of the barrel, the material left moves inwards. In the case of threading the end of the barrel, this may be a good thing on a 22 barrel, as you will create "choke" at the end of the barrel, and it may be a more accurate barrel.
I'd have a good gun smith do it!
Going to post elsewhere on the forum, as others may be interested.
One of the guys who helped write the article is some professor at Purdue U.