Hello again,
I tried this fix by myself and it works, but there is one drawback.
You will have to get some files from the other version.
I'll post You a download link:
The Peter Games version is missing a few files.
Please put them in the correct folders.
The files:
Effects\GunFire\050_089mm\mono.sim
Effects\GunFire\007_009mm\mono.sim
Effects\GunFire\020_049mm\mono.sim
Effects\GunFire\010_019mm\mono.sim
All of them are called mono.sim
You should put each one to the corresponding folder in the Effects\Gunfire folder.
Unpack the ZIP file and place the correct mono.sim file to the correct folder.
You can also simply replace the existing folders in Your GunFire folder
Files can be downloaded from here
http://www.sendspace.com/file/pawy58
I'm also adding it as attachment.
Please try this solution and write if it helped anyone.