Look, I rather like them and all, but as a guard player I have them in spades on my vehicles so I'd never outfit infantry with them if I was playing competitive.
You're really focussing on anti-infantry with them, because even in a pinch they'll have a relatively low chance at cracking light armour such as scout sentinels, kans, trucks and rhinos.
That being said, s5 hits on t4 creatures is always nice, especially if you are just looking to generate volume of fire advantage over an opponent.
In summary, Autocannons are the better option in my opinion, but heavy bolters are ok!
You're really focussing on anti-infantry with them, because even in a pinch they'll have a relatively low chance at cracking light armour such as scout sentinels, kans, trucks and rhinos.
That being said, s5 hits on t4 creatures is always nice, especially if you are just looking to generate volume of fire advantage over an opponent.
In summary, Autocannons are the better option in my opinion, but heavy bolters are ok!
