I don't lecture people who choose to eat meat, though I would say something if it were horses or cats or dogs. I feel that those are companion animals, not meat. I don't "allow" my husband to eat meat, he does what he wants. If he wants to go to the store, buy steak, bring it home, and cook it, I'm not going to say a word.
I have done plenty of research on slaughter, read books, watched the videos, been to the killer horse auction etc. I don't think that former commercial slaughterhouse workers who report the horrors that they have seen are making up stories just for fun, nor do I think that people on hidden camera documentary video are just acting like sadists for the cameras. Taking life day after day, in a high pressure assembly line environment, is going to desensitize even a normal person eventually. What was once a horror isn't going to seem as awful if you see it day after day after day. That's just basic human nature.
If any vets around here are using captive bolt guns to put horses down they keep it a pretty good secret. I've seen horses euthed by vets, and it's been IV. Besides, a CAPTIVE bolt gun doesn't kill an animal, it just stuns them so that the heart still beats and they will bleed out easier when the throat is slit and the animal is hung upside down.
I have never read any information (on either the pro or con side, yes I've researched both sides) that mentioned slaughterhouses using a penetrating bolt gun to actually kill the horse prior to bleeding it out. I am certainly open to reading reliable testimony about humane horse slaughter. I've looked, and had yet to be able to find any such thing. I'm always open to hearing both sides.