Leo,
Teague replacements for factory OEM chokes are available for lots of makes and models. If you're asking about thin-walls, then only Teague in the U.K. can do that for you, and yes you'll have to ship your gun. No one in the U.S.A. or Canada (to my knowledge) is authorized to do that work for Teague.
I always buy my barrels from Litt's in Wales and have Andrew send them to Nigel Teague to be choked. When the gun is then imported into the U.S. it goes through Charlie Schneible at British Sporting Arms Ltd. Charles can also act as your exporter if you need one. See his site at:
http://www.bsaltd.com/You could also have Briley do the thin wall work and either use Briley chokes or Teagues...the thread pattern is the same. See Briley at:
http://www.briley.com/The Teague web site has been down lately...perhaps it's back up now. Otherwise call Nigel Teague at: 011-441-454-260-226
