Modification totals tens and if not hundreds of changes of balance of game, transforming it beyond recognition, but strongly approaching all game world to reality. For example, the quantity of cartridges and rate of fire, practically, at all types of weapon are changed to more realistic.
Copy the folder in the directory Battlefield 2 \\mods. Then in the Battlefield 2 folder \\mods \\bf2_realism \\Levels launch the bf2_realism_setup.bat file. Enter game in the Community/CustomGames submenu find the necessary modification and activate it.