ive never seen it done,, but my gramps said he would stick their head in the cone,,,, the cone was big enough for the whole chicken to fit in, ( he worked for the state DOT,, so he had 1 of those good road cones
) and he would chop, then tip the cone over so it was standing up, and they would just flop around in the cone.,,, you could wrap them in an old towel, and chop their head, then the towel keeps them from flopping around,,,,too much
.
but,, dont take my word for it,, i just tie them up by their feet
,, that way i dont have to pick them up and tie them so they can bleed out, that way i save a step
,,, im wicked lazy