Here is a tutorial on how to Buy Classified weapons at any level.

1. Get a friend to invite you into a Combat Training lobby.

2. The navigate to the desired Classified Weapon. (Needs to be visible. i.e G11 in Assault Rifles)

3. Now click the weapon and when it says "BUY AND EQUIP" have your friend change back to Player Match.
NOTE:This will take cod points off your online amount.You need to be the required level to unlock the gun in Combat Training.

Requirements:

Be at least 14th Prestige on Combat Training
A spare 50,000 CP to spend (Not Combat Training)

Instructions:

- Reach the desired level of at least 14th prestige on combat training
- Get your friend to invite you to a Combat Training lobby
- Go to your create a class and choose the gun and class (1-5) you want it for (set the class the same as your online one)
- Now go to camos and select the Gold camo and click on it, then highlight DONT SELECT Buy and Equip
- Once you have that highlighted, get your friend to switch lobby to Player Match or Private Match and hit the Buy and Equip button now

It will take the 50,000 Cod Points from your normal playercard

Hope I helped some of you guys