You might want to brush up on your logic, you quoted some facts from a biased source and left out things like a clear premise and conclusion, along with the necessary points in between. Here, let me give you an example:

Premise: Guns are incapable of murder
Argument: Murder is defined as "the crime of unlawfully killing a person especially with malice aforethought" or "Under most modern statutes in the United States, murder comes in four varieties: (1) intentional murder; (2) a killing that resulted from the intent to do serious bodily injury; (3) a killing that resulted from a depraved heart or extreme recklessness; and (4) murder committed by an Accomplice during the commission of, attempt of, or flight from certain felonies". There is no credible evidence to indicate a firearm is capable of of any thought or emotion, such as malice or any intent good or ill.
Conclusion: A gun, possibly excluding one that is able to pass a Turing Test, can not be said to murder someone.

Guns are very durable items requiring minimal maintenance so resell is nearly perpetual, again, that is rather the point. Beyond just resell guns are very durbale, very portable, and very valuable. It isn't just that to someone can say it was lost or stolen, they are regularly stolen in house burglaries. So there is always an easy black market for these.

No kidding

How could such a thing be done? Do you propose that I should not be able to sell or give a gun to a friend without checking his background and logging on some national registry that this was done?

Yeah, absurd hyperbole, very convincing. Tell you what, if it's just some paperwork, suggest to the NRA that we have those forms filled out then burnt immediately upon signature, they won't object. It's not the paperwork, it is the information contained there and who gets and who can actually do the paperwork. It is immoral to impede second hands sales and commerce by requiring serious hurdles just to sell a single used object or a handful of them. I am not responsible for what someone does with a computer i sell them, if they decide to use it hack to DoD or CIA that's on them, not me, and I've no obligation to tell the government what I do with my personal property, be it a PC, a gun, a book, or a Christmas gift.

Any University's 'center for gun policy' isn't likely to strike me as a non-partisan source, especially when it's the John Hopkins Bloomberg School of Public Health. Not really a good name association on guns these days, and not coincidental, Mayor Bloomberg is the big donor in question. It's a gun control advocacy group dressed up as something else with as much claim to neutrality as CATO, Heirtage, or ThinkProgress.