Chang was a normal person with extraordinary abilities in the martial and healing arts of China. When I met and trained with him, he had come to a place in his life where he had done it all and seen it all, in life as well as in the martial arts. he was also healthily sceptical and had a good sense of humour. So it was usually like trying to pry a chicken from an Aussie snake's mouth as far as getting information out of him was concerned. However, when he did offer some answers and advice, it was like precious pearls of wisdom. So when he spoke and demonstrated, I listened and took notes.
When I asked him about 'iron shirt training' or iron vest training and practice his answer was as usual precise and to the point. He told me to go and strike 'that stone wall' as hard as I was able. Of course I didn't. He asked why so I told him that I would damage my hands of course. He then asked me to go and strike that 'person' walking down the street. I replied that I could but wouldn't. He then said that that was my answer.
Upon questioning him further and with great reticence, he told me further the following. I am paraphrasing here and working from old notes and memory. His English was not good. People in the West think that they can become Superman by training in a few simple Qigong methods that will make them impervious to attacks to all parts of their body. If their martial system was that good, they would not need this anyway. There is nothing supernatural about 'Iron Shirt', it is based purely upon physics and not upon some magic stuff called Qi. Using physics you are able to withstand normal types of attacks mainly to the torso region. The reason is that we are human beings and as such, we inherently do not wish to hurt anyone, especially our teacher. So when we are asked to strike the teacher, there is an inbuilt protection that stops us from really striking that teacher, especially if he is old like me. So the sub-conscious mind holds back the real power.
Take a look at how most people punch; they only use the arm, not the whole body. This type of attack is easy to use iron shirt against, even to the neck sometimes. But when someone is trained in the brain of the reptile, you would strike using the whole body and no-one would be able to withstand your blows. I have heard some say that they can withstand blows to the neck region. How can this be so? If you were to strike the neck properly, your hand would end up many inches past the neck, taking the middle of the neck with is. So the neck would be broken easily and all of the iron shirt training in the world would not save him, this is basic physics and logic. Chang then asked me to strike him so that he could tell me about real iron shirt as he saw it.
I threw a punch to his face and he simply moved his head to avoid the punch. He then asked me to not hold back. I threw another more powerful and quicker punch, again he simply moved his head to the side. he told me that I was still holding back and to attack again, this time to do it without thinking or telegraphing. So this time, I really let go and woke up on the ground. Chang revived me and then asked me; 'do you know about iron shirt now'? I said 'Yes'!
I have demonstrated on video the iron shirt by having people attack me with powerful punches to the body and even the neck. However, this was only physics, nothing special or magical. At one time (on DVD) I even ran flat out onto a knife edge strike to my neck and survived, although a little sore afterward. Again physics and not Qi. However, and here's the rub, in order to do that kind of iron shirt, I would have to forego my self defence method! Because one always has to get ready for taking blows. In a real fighting situation (an no-one demonstrates iron shirt in this situation) we are too intent upon self defence to waste time getting ready for an attack. Much better to NOT be hit than trying all of your life training to take blows!
However, it is always good to know what being struck feels like and what effect it will have upon your body and mind as the old saying of 'it is 50% shock value that loses you the fight' holds true. So training in iron shirt does have a value, in that it trains the body to take certain blows to alleviate the shock value. Like a boxer who is used to taking blows all over his body, the normal person in the street would be defeated on only one of those blows. But because the boxer is used to it, it has to be a really telling blow that affects him greatly.
Remember, that anyone can learn how to take certain blows. But no-one can stop real fa-jing attacks.