It certainly can break the skin and do serious, even fatal, damage. I shot a friend by accident as a kid (no excuses, I handled the gun carelessly) He went home and told his parents what happened, he went to the hospital. Since ‘gunshot wound’ went out over the EMT’s radio the police showed up at the ER and my home. Doctors determined it would be best to leave the BB in place (right chest). It could have been a whole lot worse. He and I are very lucky.