This is a multiplayer achievement and can only be done in ranked matches.
If you have the Golden Gun while playing Golden Gun mode, you will kill people in one shot. The bullet will explode once it makes impact after you shoot it and because of this, it is very easy to kill people with this gun. The easiest way to get kills with the Golden Gun is to aim at the ground by your enemy’s feet. The bullet will explode on impact and kill the enemy. If you aim at their feet, you don’t risk missing the person and having to shoot more. If you keep playing this game mode, you will get 100 kills with the Golden Gun over time.
If you need help with this achievement, please use the Quantum of Solace Achievement Trading Thread.