I've never had problems like that. I suggest you just to practice light/medium ballbusting and let the hard ballbusting stuff for professionals. Not everybody can take what Brother Love can.

My first experiences were with scorts, but I always explained to them the limits of the things I wanted. Since I was able to meet several gf willing to do it, I always told them what was pleasure and what was too much.

So no matter how far you imagination might go, just keep in mind that your testicles are not steel in the real life. Better to watch hard bb on the Internet than visiting a doctor in the real life. And try not to practice ballbusting while you're drunk, you might not feel the pain at that moment but next day you can find a dreadful surprise between your legs.