Dozens of firearms lay spread out on tables at the LAPD's Hollywood station this week—all seized in a six-month undercover sting against LA-area gangs, the LA Times reports. What's unusual is that they're all "ghost guns," partly homemade weapons without serial numbers traceable by law enforcement. "Criminals are making their own weapons because they cannot buy them legally … or they are paying other people to make those guns for them to get around the gun laws," says Bill McMullan, an ATF special agent in Los Angeles. "This is a trend among Southern California gangs." They're also increasingly popular nationwide among criminals and gun enthusiasts who want to stay off the federal radar, the Wall Street Journal reports.
A buyer just purchases an "unfinished receiver"—also called a "lower receiver" or "80% receiver"—which houses the firing mechanism and doesn't require a serial number when sold; what's more, the dealer doesn't have to be federally licensed to sell firearms. Drill in a few holes, add a stock, upper receiver, barrel, and trigger mechanism, and presto, you have an AR-15-style weapon like the ones seized in Los Angeles. The parts cost roughly $700 and can be worth $1,000 to $2,000 on the street. Some US officials (like New Jersey's attorney general, NJ.com notes) are seeking a formal ban on unfinished receivers, but for now they remain legal. "There is a loophole under federal law that allows an individual to make a firearm," says a federal prosecutor. "[But] the person breaks the law as soon as they are transferring that firearm." (Read more firearms stories.)