Dan Wesson 357 magmum ctg with a 2 barrel how can you tell if it will enterchange to different size barrels?

Dan Wessons have a nut inside the front of the barrel that has to be removed to remove the barrel shroud and barrel. Keep in mind that Dan Wesson barrels are two pieces, the barrel itself, which is just a rifled tube that is threaded on each end, and the outer shroud. Once the barrel nut is removed the shroud just slides off and the barrel can be unscrewed from the receiver. When you put another length barrel on the gun you just screw in the new longer or shorter barrel tube, slip the shroud in place and tighten the barrel nut to hold everything in place. There is a special wrench that is designed to remove and add the barrel nut. You also need to be careful and measure the gap between the cylinder and the force cone of the barrel. DW makes a gauge to adjust this properly. If the distance is too small the cylinder can bind as it turns. A too-large gap effects accuracy and can be a safety problem.