Hi, 
  Some time ago I'm looked for soundtrack in AoP which started plaing when We had low hp points. When I found it, I got idea to change sounds for some weapons and here is resultat:
http://www.speedyshare.com/MhyA9/nowe.rarUnpack by winnrar and place all sounds without "0" to YourAoPfolder\data\sound\fmod
and "0" to YourAoPfolder\data\sound\fmod\bgmName of track    change for:
-7221                 M240 (bg)
-3811                 bg sniper riffles
-4811, 4812         ripper
-7611,7612          avenger
-7621,7622          minigun
-0                      Hymn USRR  (I change it for hearthbeat) Its not that loud and anyoing.).
Hope You anjoy.PS. Every Time when we update game, sounds are change on originals, When You want keep those my, copy them somewhere to own folder.