To answer your question, i was using this server sided mod that you can keybind different phrases too. Once the binded key is pressed, your player will shout a command. The original voice overs were the Scout from TF2. However i went in, made a custom audio description, and added my own Voice overs.
Whenever you hear "Frag Out" or "Reloading" those sounds are built into the guns i have, which i have released.