It appears that the Firestorm will not let you start with your loadout. Instead you will have to loot and forage for weapons as it is with other BR's.
I'm not really interested in this game mode however I am going to try it. The fact that I can't use my loadouts is a big thumbs down. Its one of the main reason I don't play any of the other BR's I say 'Yay" to letting us use our own loadouts.