I think I had a bunch of complicating factors that combined to make this as miserable as it was... Yeah, the boys were quite big and strong, and I'm small and had no help. Maneuvering them in position by myself, especially without having enough experience with this particular method, resulted in everything taking longer than I'd hoped, including longer for the birds choking with the stick over their necks. What made things worse is that those cockerels weren't mine - somebody was getting rid of them and I took them for the meat. So they didn't know me, they were scared, and they fought - hard! One of them was a giant Brahma mix, wrestling him made everything more difficult, and took longer. I tried to calm each down as I took him out of the crate - I held him and pet him until his hackles came down, but they were still on high alert and resumed fighting me as soon as I put them on the ground. By comparison, when I process chickens that I've raised myself, they know me and trust me and go along with everything, with very minimal resistance. It's a little sad actually - breaking their trust... but it does make the process a lot easier for me. But these guys were in a strange new place with a stranger handling them, and were freaked out to start with. They hadn't been handled much, unlike my chickens which I interact with daily and are socialized, so that plays a part, too. Wrestling semi-wild birds who are resisting makes everything extra hard. My husband can't help me because he really doesn't like killing things, even the mice I have to take care of myself if the traps don't kill them the first time but catch their hips instead etc. So I need to find a killing method that doesn't require a second pair of hands. Maybe this just isn't it, for those reasons.
I agree that hanging them upside down is bad but only if 1) they hang like that for prolonged periods of time, and 2) you expect them to live after that. So like hanging them for reasons other than to kill them. But if they are going to die anyway, and you only hang them for seconds, the arguments against are moot. When I use my original method with the cone and the shears, the bird doesn't spend almost any time in the cone alive - I put it in, grab the head, and cut. It's dead before it knows what happened. When it's one of my birds, like I described above, it's calm as I put it in the cone because they trust me and I can pick them up and handle them without them freaking out. So I carry it to the cone as it's relaxed in my arms and talking to me, inquiring about whether treats would be involved in whatever this is. Once it's in the cone, I've noticed that both my birds and other people's birds that I've processed like this, get very calm once inside, looking confused, and not gasping for air at all (for the split seconds they are in there before I cut and they die instantly). By comparison, the cockerels with the broomstick on their necks fought and kicked and gasped, and were in visible distress, unlike the ones that go straight in the cone. So, both for practical reasons for myself, and for the sake of the bird's comfort, I'm going back to the cone + snip method...