I will be showing you how to get classified weapons at ANY level. I do not take any credit for this im just telling you how to do it.
Ok so first, Have a friend in a Zombies lobby. You must be on the Menu where it says Store, Options, Local, Xbox live etc...
Next you want to click the Big button on the middle of your controller, Then go to your friends name and join his session.
When joining it will take you to the MAIN menu, when it says click start, click A (or start), then Down and A (On multiplayer) and click it as fast as you can.
Just wait a bit and you should be back to the multiplayer menu, now you want to click on Local, then system link. Just wait until yhou get an error, It should say something about incompatable game version or something.
When you get the error you will be kicked back to the multilayer menu, just go back to local the system link, then create game. Now click on edit game options then go down to class loadout or something and change it to custom classes and click A.
Now click on edit loadout and buy your Classified weapons. NOTE: The money you use to buy the classified weapons will be took from your xbox live cod points.
Finally go to xbox live and choose your classified weapons