Question about mastery and rarity upgrade

i know when it goes F2P you can upgrade weapon rarity and when you upgrade a mastered weapon you keep the mastery, but my question is when you upgrade a unmastered weapon does the hidden mastery stay the same or does it change when you upgrade it?
so for example say you have a purple wolfhound and the hidden mastery roll is going to be a x0.85 reload. when you upgrade it to orange will that hidden mastery roll stay the same or change to a better reload say x0.80 or will change it to a different roll altogether?

The mastery is rolled when the weapon is created, it is just hidden until you master it.

So if you have a common weapon it will have the common mastery bonus unless after you upgrade it to uncommon and reset mastery, then it will use the uncommon mastery roll list.

Sorry for the confusion, when you upgrade rarity your hidden mastery it will remain unchanged.