Stunning animals before slaughter

Can Mufti Saheb please explain how come stunning of animals before slaughter is not permissible. I only eat the meat of unstunned animals and my family members are saying that they have never heard of this and I'm making up my own rules and all these years everyone has been eating meat certified by Sanha.

I was also told that by stunning of all animals, is torture to the animal, can result in death, which is hard to ascertain at the time of slaughter, as the animal is already unconscious due to stunning, and that it also prevents the animal from kicking and the heart pumping out all the najis blood that makes it halaal, as the Islamic way of slaughter (as one has to cut the jugular and 2/3 arteries in order for all the najis blood to flow out) and that stunning of livestock (cows, sheep etc.) is reversible. In this case won't the meat of the animal that is stunned be carrion and haraam in any case?