Re neck breaking the quick old fashioned way .
Grab the chickens feet in one hand & their neck in the other , putting the neck about 2" behind the eyes between the middle & ring finger . Now put the neck across you knee as you stooping slightly and then stretch & twist the neck over your knuckles to break it by pushing your hands apart apart. You'll feel it break , keep hold of the feet till the bird stops flapping .. good for up to 50 or so birds in one go but it then starts to get physically tiring .
Re The broom stick method :-
An iron bar about 30 inches long is just as good , all you need to do is put the chickens neck under the middle of the bar & on a flat surface then . Stand on both ends at the same time no need to pull the chickens feet to separate the neck if your over six stone in weight . You might find it's useful to do this standing by a wall for support in case it's your first time & you get all emotional & queasy .
Once you've dispatched half a dozen chickens & eaten them it won't bother you even if they were former friends / pets .