Melta quite powerfull and balanced.
Shotgun - best weapon in game for the moment on my opinion. Fun, powerful and comfortable to use.
Lasgun - i thinq it must hawe more fire speed. Its more advanced weapon then autogun, but autogun can spray a bolts like a hell and lasgun dont i think its wrong. Its only my opinion of cource.
Hevy bolter. Quite dissapointed like a lasgun to small fire speed. It powerfull no doubt but fire speed make it usfull only big targets. Its just uncomfortable in the task to neutralise hords of small targets, despite it is his mayne job.