"Indeed, 18-to-24-year-old women are especially likely to be targets for rape, but more broadly 18-to-24-year-olds are especially likely to be victims of violent crime. It’s one thing to deny the necessary tools for self-defense to people who have long been recognized and children, who are both especially immature and usually under the protection of their adult parents. But I don’t think that it can be justified to deny the same tools to people who have the responsibilities and life patterns (living alone, working, and the like) of adults. Banning gun possession by 18-to-24-year-olds will do little to protect them from violent crime, precisely because most people willing to commit rape, robbery, murder, and the like will also be willing to violate gun control laws. But it will do much to interfere with young men’s and women’s ability to protect themselves from violent crime."
From Eugene Volokh's response to a WaPo column recommending "raising the minimum age to buy or possess (without adult supervision) a firearm to 25."