At The Gates: Custom W2000 rifle
Use the following trick to get the W2000, which is best sniper rifle (the only one that is silenced). Start the mission with a rifle and take out the guards in your sight. Follow the road and be ready for the "Sniper has acquired target" message. After this, quickly run back a few yards, and he will probably lost you. The snipers are at towers to your left. At your left it is a hill that helps give you cover. The first sniper at the tower at the right is an easy target. After him, you will see another one at a higher tower. Do not shoot him. Walk back and save the game. His rifle is very fast and powerful. Use your sniper rifle to shoot him, but do not try to kill him with a headshot. You must hit him lower than his rifle. If done correctly, you will see him dropping his rifle out the window while falling back. Do not run to take it, as another sniper is at a tower to your left. Use your map to find him. Kill him, then find the rifle. It is a custom version of W2000 with very powerful shot and is silenced. You can kill multiple enemies with one shot. Note: Do not stop trying if he does not drop the rifle; try to hit him at the correct spot.