The Seattle Police's gun buyback event yesterday turned into an ad hoc, unregulated flea market for weapons, with a Stinger missile launcher as the headliner.

The event, paid for by private donations, drew such a crowd that the buyback line stretched for hours. That made the private gun buyers, hanging out at the edges, a more attractive option for some, including the guy who sold the non-functioning missile launcher to a private collector.

That's not explicitly illegal. Washington state law does not require background checks for private sales, a provision commonly known as the "gun-show loophole." No background checks mean anyone - felons, the severely mentally ill - could saunter up, cash in hand, and buy a gun they'd be prohibited from buying from a federally licensed dealer.

It was clearly a failure of design for the event. Holding it in a parking lot, under the I-5 overpass, allowed the SPD to lose control.

It also spotlights the absurdity of exemptions for private sales. Dave Workman, senior editor The Gun Mag, said most buyers appeared to have concealed-weapons permits, which require a background check.

I hope so, but laws are written with the worst scenario in mind. It also brings to mind a case brought by U.S. Attorney Jenny Durkan in which an unlicensed dealer sold the rifle used to kill Seattle Police Officer Tim Brenton. The seller, David Devenny, literally exploited the gun-show loophole, selling the rifle at a Puyallup gun show.

Background checks are required for a damn good reason. Extending them to private sales is logistically and politically tricky. The state Legislature could consider requiring private sales go through licensed firearms dealer, adding some to the cost, but assuring background checks are done.

Another buyback is already being planned. As I noted a few weeks ago, these aren't very effective at reducing gun violence.

But at least let's not let it turn into another flea market.