i was out culling rats yesterday and was working at a rat of about 20 wpm(wacks per minute) quick, easy, effective. pinkies are easier, hold their head and flick them in the brain, dead in seconds. i find using a brick is more humane then co2, and ffaster, if i have 70 rats to cull, i can take 5 mins smacking them on a brick, or i can spend 4 mins setting up a gassing chamber and another 3-5 mins waiting for the little buggers to die. then doing it all over again because the gass chamber isnt big enough.