Originally Posted by neeker75
For those missing guns, just redo Civil Discord. You'll get the Anti-Riot Guns (both of them), the Assault Rifle (non Tac-Light) and the grenade launcher. Got my Gun Nut achievement without even trying.
The Funeral also gives you the grenade launcher.
Funny. I just did the entire Civil Discord mission, looked everywhere, and not once did I see the anti-riot gun without the taclight. Just the one I need. *sigh*
Edit: I just got it by replaying the mission "meet the new boss". I needed the .50 cal silver pistol. The game was just calling it the .50 cal pistol when I picked it up, but I got a kill with it, and achievement unlocked.