Tracking guns is a major challenge in a country where the majority of the population sees gun registration as either a personal insult or an attack on the Constitution. The resounding 1997 defeat of state I-676, the handgun safety initiative, was proof of that. Kids looking to make a big haul might knock off a gun shop. In one case from 1997, a crew from the Young Oriental Troop, a Rainier Valley gang, was caught trafficking guns stolen from a Wenatchee gun shop. The owner of the store was murdered during the robbery.
Gun shows are good too.
Second-hand sales are similarly unregulated. If you buy a gun at a shop and sell it out of your car trunk, nobody has to fill out any pesky paperwork. Sure, there are laws in place to keep guns out of the hands of young people. Nobody under 18 can buy a firearm of any type, and people under 21 are forbidden from purchasing handguns. Federal laws say adults can't buy guns for, or loan guns to, minors.