GAS? what purpose can that possibly serve. To each his own, and you can do a bird in any way that you choose, still I think about what is real, what is cruel, what is necessary, and what is wasted effort/resources. Severing the head is instantaneous 100% death, it can be done with less trauma to the bird than shoving it into a box in my humble opinion.
We could send chickens into space, and the lack of oxygen as we approached the upper atmosphere would make them pass out, and as they reentered the atmosphere the heat would burn the feathers off and cook them Yum, just get out a net and catch em. In the process we would break the world speed record for the fastest bird too, LOL
No animosity, ill thoughts, or tension meant at all here, just my attempt at a funny, and showing that you can over think anything. Chopping block, hatchet/cleaver end him, humane fast, no wasted resources. Rough on the newbie chicken killer human, easy on the bird. Well as easy as it can be.