spedray
If you want to do it yourself you will need a a barrel vice, a barrel nut wrench, go and no go gages for the 6.5. The barrel vice needs to be a good one. I have one that I got for $75 off the Internet. I forget where I got it. It is two pieces of bar stock steel. When you put the two pieces together with bolts there is a round hole that is formed in between the two pieces of steel. In that hole you insert a 1" long piece of aluminum pipe that has been split so the ID can shrink when the bolts are tightened down. Several different diameters of aluminum pipe come with the vice to hold different diameters of barrel. You can make small adjustments by wrapping strips of paper or such around the barrel.
Anyway, clamp the barrel in the vice. Slip the barrel nut wrench into the grooves on the barrel nut and break it loose. On a rifle that is as from the factory I will give the wrench a couple of taps with a hammer to get things started. Unscrew the receiver from the barrel. Clean up the threads in the receiver and the new barrel if needed. Clamp the new barrel in the barrel vice. Screw the receiver onto the new barrel with the bolt closed until it stops. Back it out a bit. Insert the go gage in the action and close the bolt. Screw the action onto the barrel until snug on the go gage. Tighten up the barrel nut. I'm guessing 100 ft lbs or so which is a pretty good pull. (If you don't get it tight enough the gun will send the 1st shot high and then group other shots a few inches lower.) Verify that the bolt will NOT close on the no go gage and that it will close on the go gage. You now have a barreled action ready to go.
Once you learn how to do this you can mix and match barrels all you want. It takes about 10 minutes.
You don't need to change bolt heads or magazines in this instance but sometimes you do. There are videos out on the Internet that show you how to swap bolt heads. (And how to change barrels for that matter.)
Just today I bought a new Savage in 300 WSM. When I shows up next week I'll be swapping the barrel out for a 270 WSM barrel I have sitting here. In this case I won't need to change anything but the barrel either. If the mood strikes I can also put the 300 WSM barrel back on.