Call Of Duty: Modern Warfare – Tunnel Rat Achievement & Trophy Guide
In Mission 10: The Wolf’s Den, after you enter the tea room and open the hatch on the floor, there will be a mid-mission cutscene. You will then drop down to a dark tunnel area. This is where the trophy starts (before the tunnels you are still allowed to use other weapons). After this point, only use the 1911 pistol.
You will automatically hold it in your hands after the tunnel cutscene. You also get new ammo for it, in case you use up your previous 1911 ammo. However, you still cannot spray bullets unnecessarily, as there is not too much ammo. It is recommended to play on the Recruit difficulty and only perform headshots.
There are also ammo drops throughout the tunnels. Just avoid running out of ammo and do not shoot any other weapon. After defusing the cables at the end of the mission, you will get the “Tunnel Rat” trophy & achievement.