If your under 21, are you allowed to purchase handgun accessories?

The parts are not considered the gun, the frame is. Doesn't matter, today marks the day when all future handguns need to be capable of microstmping in kalifornistan, 2 months from now handgun ammo will be registered and you will only be able to buy 50 rounds a month. Handguns have been made almost totally illegal now unless there older models.