In my state you can buy, sell or trade guns with any private individual without a paper trail, same in many other states.
Don't get why they call this a "gun show loophole" because you damn sure don't need to go to a gun show to do it. At the gun shows I attend, private sellers are generally only a small percentage of those selling, most are dealers and standard paperwork is required.
If you know your trade and keep up with the trends, you can go into a gun show with a couple hundred dollars and walk out with a couple thousand dollars a few hours later.
As a long time gun nut, collector, I am calling B.S. on this statement however. If it was that darned easy, we'd all be gun dealers, all gun dealers would be rich, and there would be a lot more gun stores. Fact is, it's harder now than ever to get great deals on this stuff due to the access to information available to the average buyer / seller.
Are there some deals to be had? Sure, but the above statement is a huge exaggeration. The best deals I've run across are guys in a pinch for quick money, going through a divorce, etc.