You get points for healing teammates but healing does not in any way make you a master of your weapon so consequently only using the weapon affects your "weapon mastery". Also, a lot of players are currently complaining about the plethora of challenges that push you into playing one playstyle to unlock things, we really don't need weapons to also be tied to that. If I use my LMG without a mount, let me do that, don't force my to use it mounted, and so on. Just by using your weapons normally without any special attention put to mastery, you will unlock your camos one by one, no need to rush.
