They can be found by going down this file tree:

Steam --> steamapps --> workshop --> content --> 108600 --> 2667899942 --> mods --> VFE --> media --> scripts --> VFE_weapons.txt

The folders "108600" and "2667899942" correspond to Project Zomboid and this mod (VFE), respectively. All PZ mods have an ID like that, and if you want to look at their files, you can probably go to the mod's page in the workshop to find it (that's how I found out which folder corresponded to VFE).

The file is almost 6K lines long. I don't recommend changing anything in it – please just use it as a reference.