don't forget theirs skin and flesh before any knuckle making impact on anything let alone metal. you going to need iron skin and flesh before you can have metal knuckles.

I was bare knuckle shadow boxing a few month ago and I miss the punching bag by a few inches and hit the side of the wall and my knuckles swelled up and my skin torn with the flesh expose. Thats the reality even if a tough tough men say it doesn't hurt. the human body will bleed or swell up when the impact is strong. Anything else is pure bullshyt.