Instructions
Load the "Call of Duty 2" game disc on your console and select "Multiplayer" from the main menu.
Select the "Custom Classes" option from the menu and decide which rifle you want to use.
Choose "Silencer" from the attachments menu after you select your rifle and then finish building your custom class with the desired options.
Join a match and use your rifle. You will notice that when you shoot that the rifle is much quieter and no longer has a muzzle flash.