High-end weapons that usually require Uplay (Ubisoft Connect) points to unlock. In the Complete Collection, they are unlocked from the start.
It sounds like you’re referring to a of Far Cry 3 (likely the “Complete Collection” including the Blood Dragon standalone DLC) from a group named ElAmigos .
Far Cry 3 Complete Collection " (frequently distributed by ElAmigos) follows the story of Jason Brody