I picked up a gun and saw it had a Grenade Launcher and a Guass Attachment, but they were locked. I TRIED to find out online how to unlock them, but theres no guides out yet, and the few forum discussions I've found all refer to multiplayer unlocks.
How do I unlock weapon attachments for campaign mode? If I have to grind my way through multiplayer sessions just to do it, I'll be extremely pissed :/