The SoundSet mixer seems to have issues when more than one SoundShaders are used.
In the attached files you will find a pbo that replaces sounds for normal MX rifle AND the MXSW light machine gun.
Normal MX uses SoundSet "MX_Shot_SoundSet" which has only one SoundShader: "DS_FPSound".
MXSW uses SoundSet MX_Shot_SoundSetDirty which has two SoundShaders: "DS_FPSound" and "pinkNoise".
IMPORTANT!!! PinkNoise SoundShader has volume = 0, also RangeCurve defines that it is SILENT up until 100m. Still, it breaks sound.
SoundSets MX_Tail_SoundSet can be ignored because for testing purposes the volumeFactor has been set to 0. {F27997}