To change the barrel and do a proper job and do it without damaging your frame you'll need the following tools.
They can be bought from Brownell's.
Bring a loaded wallet and hold your breath on the cost.
This is why the best advice is to have a professional pistolsmith do the job.
The tools will cost FAR more then the job by a pro......
Revolver frame wrench with polymer inserts that are made for the S&W "K" frame.
(Do the old gag of sticking a piece of wood through the frame window..... kiss your frame good by, it'll often crack under the barrel threads where it's very thin, or the frame will bend)
Barrel vise setup to clamp the barrel.
This can be made by routing and glass bedding grooves in two hard wood blocks and using a large shop vise.
Cup ended pin punch to push out the barrel pin without dinking up the end.
Lathe or bench top cutting fixture to turn down the barrel shoulder so the barrel will align with the front sight at 12:00 o'clock top-dead-center.
(Barrels don't just screw in with the proper torque and the front sight aligned. Barrels are not just a fancy piece of threaded pipe).
Special cutting device that works down the barrel to cut the rear of the barrel square and so the proper barrel-cylinder gap is set.
Special cutter head for the above tool used to re-cut the critical forcing cone in the rear of the barrel.
(This is far more then just a funnel that can be eyeballed).
Special brass lapping plug and fine valve grinding compound used with the above tools to lap the forcing cone.
Special plug gauge used to gauge the forcing cone for proper dimensions.
(Critical..... get it wrong and the gun spits bullet metal or is inaccurate).
Best advice.......
Unless you're going to be doing a number of rebarreling jobs as a hobby or a business, or you don't mind ruining a good gun, have a pro do it.
Pros to do it at a reasonable price are...
The S&W factory.
Frank Glenn.....
http://glenncustom.com/