Since you mentioned a K frame sized revolver try to find a dan wesson 14 or 15-2 with the recessed barrel nut. On those pistols you can change barrels lenght in 2 minutes. Want a 2" or a 8" , no problems.
These are full pistol packs but you'll get the idea.
http://www.bing.com/images/search?q=...pack&FORM=IGRE