What do you guys think?

Can a Cursed Heirloom item be made into a starting Legacy Weapon? It seems ambiguous. You can make a starting Acquisition into a starting LW. But does a Cursed Heirloom item obtained during character creation count as such? Or would you have to elevate it, as it is obtained during spending of XP and not at the Equipment phase of character creation?

I really really want my character to have a haunted lasgun that reappears every time he tries to throw it away and forces him to use it and only it... nice and morbid

Short answer, yes if the GM allows it. Given your description I know I would.

I agree with Keffisch, I think the background actually makes it an awesome candidate for a legacy weapon.

Such a history is what gives legacy weapons their strength and legend.

You start with the weapon through acquisition so should be able to start with it as a legacy weapon through the normal rules. I'd certainly allow it as GM.

The gun is the weapon he used to kill his squad. It haunts him, a physical reminder of his guilt. (Regret Disgrace, of course.)