On C-Span this weekend, they televised a conference about research into gun crime. Only 15% of the guns used in Chicago to commit crimes were purchased legally. They traced back as many as they could to the original owner and 75% said the gun had been stolen, however the majority had not been reported to the police. The other reasons were transfer (sale or swap) at gun shows and individual sales. All the guns bought new from the store had a background check and were sold to people who were cleared to have them. They did not commit the crimes. However, they allowed the gun to leave their possession without following through with equal caution. The guns ended up on the street being sold to criminals.
Now, if a gun is stolen, fine, it's not your fault, but it should be reported stolen. Why would you not report such a thing? If it were my tv or my car stereo or my laptop, I would report it. Why would so many people NOT report a stolen gun? My guess is that not all of them were actually "stolen." They were transferred to people who shouldn't have had a gun and the person who sold it knew it.
Keeping the above in mind, if 85% of the guns used to commit crime in Chicago were illegally owned, and if those guns arrived on the street after being transferred without the requirement of a background check, a good way to make those guns go "poof" is to start requiring all gun sales/transfers to have a background check, or hold the last legal owner responsible if the gun is involved in a crime. That would deter people from handing over guns to folks who shouldn't have them or selling them to anyone without a background check.
It would hopefully cut down on the illegally owned guns on the street. This is my own idea, developed after hearing the studies on C-Span. It couldn't be proven without putting it into effect, but I think it makes sense.
I do not believe the Second Amendment means what you believe it means, so you can have that argument with someone who likes to argue about the Constitution. It is very clearly not infringing on the existing rights of law abiding citizens to own a gun if all I am asking for is a background check for all sales/transfers.