Hbar profiles are typically either straight 1.0” behind the gas block, or stepped down to 0.920-0.936”. Then use a 0.750” gas block, with straight 0.750” out to the muzzle. “Heavy barrels” are typically whatever the maker wants them to be, as are “bull barrel” or “semi-bull” contours. National Match contours are often similar to HBar, dependent upon the makers. Hbar and National Match profiles aren’t as popular because they’re heavy, but some of us love that extra weight. They’re also less laborious to machine, since the barrel isn’t turned in as many sections or as thin as other contours.
I use Hbar’s or Nat’l Match profiles on almost all of my personal rifles, except for the light weight go-fast guns.