actually, SWF (Salt-Water-Flush) and Epsom Salts are very different in their actions. ES actually enters the bloodstream, while the SWF, when done right, is so salty that it just passes thru the alimentary canal without being absorbed into bloodstream, same way as ocean water.
When I flushed ten years ago off a recipe my naturpathic doctor gave me, dilating the ducts was not mentioned at all. He was simply adamant that you shouldn't flush unless you first softened the stones with liquid phosfood. So I've used ES once out of all my flushes and never had a problem with stuck stones or pain or anything. :) I've passed larger than garbanzo bean sized stones pain-free.