Gov't Profle VS. Lightweight/Pencil Barrel
 

Most of the Gov't profile barrel is a pencil/lightweight contour anyway. So, what is the real advantage of the Gov't profile barrel? Seems like the thicker barrel at the end would make it muzzle heavy. Does the thicker barrel at the end really keep it that much cooler?

No it doesn't help keep it cool. Someone probably thought it would be easier to control with more weight on the end. IMO the M4 barrels are backwards, under extended firiing sessions the barrels are heating up and swelling in the thin area under the guard. The Mil is going back to a heavier profile, the mid weight "Socom".