All of steelslaver's points are right on! The other side of this is why would you want to spend $300 or so to change a $1000+/- revolver into a $600 dollar gun that no one else would probably want!
The fact is that any 4" S&W revolver barrel can vary from as much as 1/8" longer to 1/4" shorter that nominal length. Would you want to "cut" the barrel to realize only a 1/2" change that could actually be as little as 1/4" to 1/8"? There is absolutely no utility in shortening a 4" barrel to Sure 3 1/2"at all!
Can it be done, sure!
