Yep, that's why I do bare-knuckle (well, recently I've taken to wearing hand wraps, I consider it impolite to bleed on punching bags that don't belong to me) heavy bag work at the sports centre nearby once or twice a week. I'm still trying to think of more ways to harden my knuckles themselves (heavy bag only helps to get technique right). The knuckles will harden some with the heavy bag work. You could look into some makiwara training, or some smaller hanging sand bags to build them up, as well.Am curious to listen more Are you wanting to learn more about hand conditioning, in general, or the use of makiwara or maize/sand bags, in particular? Hand conditioning