The non-combat stance with a pistol, while crouched silences all footsteps, and heavy breathing sounds.
- Legacy ID
Equip pistol, double tap left ctrl key, crouch and walk.
Not 100% sure if this is a bug, but I'm fairly certain it's not meant to be like that.
Only slow walk (with default left shift key) is silent. The same is true for moving in crouched combat pace (default C key) with pistol in hands and lowered. No footsteps, no breathing.