I cannot find a note on the subject of Heavy weapons being used for pilot maneuvers.
Many maneuvers allow you to do something that involves making an attack with a weapon of your choice, but most of these maneuvers take a standard action while a Heavy weapon normally requires a fullround action. Unless a ruling is done on using Heavy weapons for these maneuvers, it makes it possible to use them as a standard action with these maneuvers. Just in case it was not intended.
IE:
Disabling Hit (Ace Pilot LvL 2 maneuver)
Standard action initiation
When you initiate this strike, make a single attack against an enemy. If you hit with that choose one weapon of your enemy. That enemy can't use that weapon for until the beginning of your next turn.
Then there are maneuvers like Return Fire (Ace Pilot 2) that allows you to make an attack as an immediate action as part of the counter. Not sure a weapon used with a fullround action is supposed to be usable as an immediate action with a level 2 counter.
Another concern:
Area:Instead of a normal shot, you may make the weapon fire a line with the width of your mecha and the same lenght as the first range increment of the weapon. Roll to hit against all targets inside the line. If you target an oponent bigger than you with this, the line needs to pass trough the middle of their position.
I wasn't under the impression that mecha ranged weapons had range increments.
I see they have a 'range' section, which seems to be fixed.
A Gespent's Split Missiles have a 50 mu range. Are those meant to actually be a range increment? If so, the misunderstanding is probably due to maneuvers and spells having a range indicator, while weapons generally have a range increment property rather than a range property.
Since I'm already talking of maneuver range, here is a question on Multitarget (Ace Pilot 3)
When you initiate this maneuver, you may perform one basic attack against each enemy within reach of your weapon.
The maneuvers mentions 'reach' but it can be used with any weapon and is limited by ammo. The description, along with the maneuver's name, suggest that it is also meant to be used with ranged weapons, but ranged weapons have range/range increment and little reach to speak of. Is it meant to use a ranged weapon's range instead of its reach?