I would agree that a fluted barrel isn't traditionally the best way to reduce weight. In addition to the options mentioned above, the Daniel Defense S2W barrels are about as light as your standard LW contour barrels will get. The lightest barrels I've seen as of late are the Ultra Light Weight barrels from Voodoo Innovations. If my memory serves me correctly their 16.5" ULW contour is a hair over 21 ounces......and you even get to run a rifle length gas set up. Assuming your current 18" utilizes a rifle length gas system and a .750" gas seat you could simply switch those components over if you chose to go with the Voodoo set up. Just my 2¢...