The Heavy Bolter is so useless every time you use the No 1skill Button most of the shot his the ground i understand the wepon have a spread but why is the inquisitor shooting at the ground LOL he is a Vid
Well, i really like the Heavy Bolter and i thinks its fine. The Problem in you video is that you just use the Leftclick at max-medium range.
The Heavy Bolter is by no means uselss, its one of the most, if not the best dps weapons if you hit more shoots on Flesh Targets with the Leftclick (so you need to go closer)
The problem is that you really have to "gear/skill" for it to make full use of it. You can have -Spread on your eye implantat (that helps a lot) and you need to go a lot closer and it needs some time to do full dps so you need to go a bit tanky.
This weapon is very "special" so its very subjective if you like it or not.
I would call your description(and the video) not a bug, especially when you shoot at a very far distance and you have some obstacles that makes the precision even worse.
Yha fo a heavy weapon its is useless right now. the hailstorm is the only on thats worth it to me and that doesnt make me want to use a gun for hyst that ability.
It's almost like when you fire your shooting in a cone not a triangle so to many shots go up and down the just left to right. hit rate like 15%
Also note the engagement range in the video is not what a rifle should be. That is the same range as what hand guns.