- Get 100 headshots.
- Get 200 kills while the weapon is above level 50.
- Get 50 kills while crouching.
- Get 50 kills while prone.
- Kill an enemy with the weapon and the stock, foregrip, and optic attachments from the same weapon type; repeat that 5 times.
- Get a double kill with the weapon without dying 25 times.
- Get a triple kill with the weapon without dying 10 times.
- Get a three-medal kill with the weapon 15 times (a three-medal kill means earning three different medals at once, such as 'First Blood' and 'Headshot').
- Get a bloodthirsty with the weapon 10 times (a bloodthirsty means getting five kills in a row without dying).
Once you've completed all of the challenges for a weapon, you'll be able to unlock the Gold Camo for that weapon.