https://www.youtube.com/watch?v=M1mIBYj5q8w
You can do that, i just buy F/T and dont let there picky habbits sway to live or pre killed due to mass amount of rat stock id need! But its pretty simple, just buying a Co2 tank and putting a little hole at the top to force the air out. and release slowly until rat is unconscious then release alot to kill them .