Gunfire: The Free Firearm Sound Library, CC0.
Recorded by Ben Jaszczak, Brian Nelson, Kevin Heras, Matthew Nanney.
https://opengameart.org/content/the-free-firearm-sound-library
Source mirror: https://github.com/petroulacl/fps-asset-kit/tree/main/sfx/firearm_sfx
AK-47 C_27P; AR-15 D_24P; Carl Gustav M45 G_24P; Walther PPQ X_31P.
DD edits: isolated attack/tail, mono, 48 kHz/16-bit, level/fade normalization.
AK and SMG: the last individual shot of a recorded burst is isolated, with a
220 ms total duration and a controlled fade. Original burst files are retained
in work/audio-assets. Rifles and pistols retain their existing recordings.

Knife/handling: Kenney RPG Audio, CC0. https://kenney.nl/assets/rpg-audio
Impacts: Kenney Impact Sounds, CC0. https://kenney.nl/assets/impact-sounds

Earlier explosion candidate (retained for comparison; no longer played):
EZduzziteh, "Explosions", CC0.
https://opengameart.org/content/explosions-4
Source: https://opengameart.org/sites/default/files/explosion1_0.ogg
DD edits: mono playback, level normalization, 0.30 s impulse and tail fade.

Active grenade-impact.wav body: NenadSimic, "Muffled Distant Explosion", CC0.
https://opengameart.org/content/muffled-distant-explosion
Source: https://opengameart.org/sites/default/files/NenadSimic%20-%20Muffled%20Distant%20Explosion.wav
The author designed this effect using a pitched log drum and reverberation.
DD edits: mono, 48 kHz/16-bit, onset trim, pitched layers for audible low/mid
impact, a brief AK-47 powder report from the CC0 firearm source credited above,
DC removal, 0.36 s total impulse with a controlled fade, and 0.88 peak level.

DEAGLE and G18 reuse the credited Walther PPQ recording as stylized weapon
profiles, with pitch, level and duration changes; these are not recordings of
the named models. M4/rifle and USP recordings and their profiles are unchanged.