So I have experienced this problem for a while.
I am unable to hear my own gunshots, but I can hear other people's gunshots.
I have posted a video explaining the problem.
Are all your content packs installed?
I thought so, but apparantly not. Installing the rest of them now.
Will reply if it works or not.
Still experiencing the same soundbug when all the content packs are installed
I experience the same issue, and I have all contents.
The Problem is the Content pack you use. There was an update that make "dirty" contents loose your own sounds. Try these:
https://kajar9.wix.com/cscheater2
Just download them and extract them into your addons like the other ones.
Leave a like if it works.
Try this:
1. Navigate to your \garrysmod folder.
Windows: (C:\Program Files (x86)\Steam\steamapps\common\GarrysMod\garrysmod)
2. Search for Game_sounds_manifest.txt
3. Delete it
If the file is not there, try to validate the game files.
If you have multiple, delete both and run the game again.
Followed your instrcutions, Jompe, and it worked.
Thank you very much for replying so fast, and if any forum moderator sees this, they can mark it as solved.