All barrels with the exception of the USH and superlight, are pretty much the same diameter at the forend and use the same forend, the bull barrels have very little taper and the sporting barrels have a bit more beyond the forend, but at the forend are pretty much the same. I swap forends all the time depending on what barrel I'm putting on, the sporting or bull contours aren't an issue.
All forend styles are listed in the 2005 Retail Parts Price list in the FAQ and Help sticky.
Tim