I think a BB gun is a great gift for a 14 year old (27yrs of age myself). I had one at a very young age and two older brothers that had them as well, and yes...we did shoot at birds and whatever, and were not always the most 'responsible'. But, I knew how dangerous a gun was, and knew what they were capable of. If you have any other firearms (or not for that matter), I would suggeest putting him through a gun safety course. Contact your local VFW, they usually have the nearest/best place to take him for some gun safety.
Educating him on safety, and giving him a chance to do it on his own, is better than a 'friend' teaching him about guns with his fathers pistol (or his own) and will give him a respect for a gun.