I have a few guns that needs firing sounds. I have tried a few sites but in game they dont sound realistic I have tried searching around for the gun but i cant find this gun anywhere. What should i do if this gun isn’t one in real life where would i get firing sounds for it that sound realistic

Can someone also link me some good sound websites i will look around on them.

Well, there’s this thing for creating your own sounds if you like fiddling around a bit.
Or you could do what this guy does: HOW TO MAKE SOUND EFFECTS - A Gunshot - By Linden Hudson on Vimeo
Or you could take an existing gunshot sound effect that sounds sort of similar and modify that with filters and effects.
Audacity is a free sound editor if you need one.