Sounds were taken from the shooter mod. Relevant section from its license.txt:

License Sounds: freesound.org

	flobert1_20070728.wav by Nonoo - Attribution 3.0 Unported (CC BY 3.0)
	
	shot.wav by Sergenious - Attribution 3.0 Unported (CC BY 3.0)

	GUNSHOT.WAV by erkanozan - CC0 1.0 Universal (CC0 1.0)

	winchester-rifle-cock-reload.wav by MentalSanityOff - CC0 1.0 Universal (CC0 1.0)

	trigger-with-hammer-fall.wav by Nanashi - CC0 1.0 Universal (CC0 1.0)

	woosh.wav by ReadeOnly - CC0 1.0 Universal (CC0 1.0)

	AGM-114 Hellfire Rocket Missile Launch.flac by qubodup - CC0 1.0 Universal (CC0 1.0)

	Sparkler.aif by Ned Bouhalassa - CC0 1.0 Universal (CC0 1.0)

	explosion10.wav by V-ktor - CC0 1.0 Universal (CC0 1.0)