Thanks to YouTuber jackfraggs, this elaborate set up from Infinity Ward has now been found. Follow his elaborate guide to get that weapon stash quick!
There’s really not much up to it if you have a guide, it only takes some memory skill and the typical FPS fare for you to survive this little puzzle.
Basically, all you have to do is to land on the government building in Downtown. Then, memorize the paintings you pass by the hallway that leads to a keypad at the end. Enter “2179”, as a lockdown gas would trigger if done correctly. Go over to the computer and remember the sequences you’ll see on the screen. Head back to the hallway and check on the numbers in the painting’s gold plaques. When you’re done figuring that out, you can go back to the computer and follow the sequence of the numbers and paintings. When that’s through, you head down to the metro station, just south of the airport. Ride a train after hailing one, and head left when it stops. From there you’d get a specialist bonus that has all the perks in game. Move over to the room next to it to get some high tier loot, too.
That’s definitely a lot of work, I hope you can follow it all! If you managed to get through successfully, let us know in the comments section below!