In a 16" barrel, the weight difference between a "heavy" contour and a "bull" contour will only be a few ounces...
You might want to go to AR15barrels.com and on the first web page, he has the a link to the dimensions of the various barrel grinds/contours...
Depending on your intended use, you may decide you don't want either of the above...I use mine for action competition matches where I'm shooting strings of 30-40 rounds in a matter of seconds and want a lower probability of heat distortion...
For hunting and general plinking, I could get by with a light-medium contour...That's why I bought the "Cheap Upper" and the Plum Crazy lower a couple of weeks ago....I want a light weight "plinker", without a lot of money involved...
All three of my carbines have a 1/9 barrel twist..