There should be age restrictions on fire arms. There is no reason that children really need guns, and it would not be safe for them to have them. There are some instances where a restriction could be waived. One of these instances would be if the parents signed off that the gun would only be used for something like hunting, and that outside of this activity the parents would lock the gun up out of the child's reach.
In most places in the United States you need to be at least 25 years old to rent a car. This is because you need to demonstrate that you are responsible and can handle something as serious and dangerous as a motor vehicle. It makes sense that guns and firearms would have the same restrictions.
I am not an expert in the firearms issue but in my opinion, there should definitely be age restrictions in firearms. Just as alcohol or cigarettes, firearms should actually be more strict with age restrictions. I believe 21 or even 25 is a good age to be fully matured and make reasonable decisions.
Yes there should be an age restriction on fire arms. There have been so many tragedies in the United States already. Plus you always have the accidental shootings. Kids today think that bad things are not going to happen to them, so they try to test their fate sometimes, not fully understanding the consequences. They are also vulnerable for believing things in movies and television are real. Who knows what some of them would do if they were given free range of having a gun.