This mod from Mudkipz makes the M16A4 burst fire and the G3 a semi-auto weapon.
This mod makes the M16A4 burst fire and the G3 semi-automatic in single player.
Install: Extract contents to your "mods" folder in the install directory. To make a shortcut to the mod, make a copy of your single player shortcut and add "+set fs_game modsburst" to the end of it. e.g. ""D:Program FilesActivisionCall of Duty 4 - Modern Warfareiw3sp.exe" +set fs_game modsburst".
Feel free to use this in your own mod.
Made by Mudkipz.