silent_auto

The .pk3 in this .zip, when in CoD main folder, turns down the volume of the automatic weapons, so you don't need to turn down the global volume.
It is done by copying the required lines from the stock iw_sound.csv file and then modifying the values of vol_min and vol_max.
To use this, the server would need to have sv_pure disabled, or CoDExtended, which patches "unpure crap", according to what is said in its source code.