Thank you for the excellent guide and the suggestion!
Question: Does this mean that attack ground on heavy vehicles is better at wiping infantry especially against infantry that is in cover. Cover will give them a 0.5 accuracy modifier so if they are close, it seems like they will hit more accurately even with scatter.
That should not be the case, but also not make a huge difference.
Infantry has a target size of ~1, which translates to a hit chance of 4-5%. So >95% of your shots will be calculated as scatter shots anyway.
The only situation where ground targeting would make sense is if your tank targets one model that is lagging behind to the rest of the squad.
I think there is some confusion what accuracy actually is: When a shot is fired, the attacker has to make a accuracy role first. If he succeeds, his shot will always hit (unless it is blocked by world objects). If not, the shot will be calculated as scatter but can still hit if the scatter was low. You won't see any difference between those shots though.
EDIT: Wait, I'm not sure if I completely understood your question. If you were asking whether you should close in or not: Yes, close in if it is safe. Angle scatter will decrease at all times, while the horizontal scatter will only be decreased if you close in further than distance_scatter_max