Theory: Auto cannons is the best heavy weapon you can get. This is your heavy-weapon workhorse. First and foremost because they are your best weapon to hammer light and medium armored vehicles and those you love to shoot to pieces. It's something you have to do as a Guard player so you do not become overwhelmed right away. S7 shots you can always use against Aforementioned vehicles, monstrous creatures, and indeed infantry, in the absence of the others. They are your best defense against transportation that roars toward your gunline.
Conclusion: To be continued
So Friday i was trimming the next batch of models i where going to paint and i noticed the heavy weapons team sprues. I just had to try to assemble a heavy weapons team. I already knew i was gonna have 3 auto cannon heavy weapons teams in my 500 point list so i started putting it together. After i put it together i had a unstoppable feeling of painting it up.... so i did.