The video below demonstrates a new exploit that has been found which allows you to mix gadgets across two different classes – e.g. an RPG with ammo pack.
It was originally thought it just allowed you to mix the weapon of one class with the gadgets of another (e.g. a recon rifle with assault gadgets) but it turns out it’s worse (or better, depending on your point of view) than that.
All that’s required for the glitch to work is to pick a class, and select one gadget while leaving the other slot open, then for the next class, do the same but in reverse. When spawning, hit the appropriate buttons to move to the next class and then back to the original (R1 and L1 for the PlayStation, R buttons on the Xbox or Shift and CTRL on PC) in sequence and you will now spawn with a combined class.
DICE have already said that anybody caught using this will have their stats reset.