For some gun enthusiasts, it’s a vision of American paradise.

A thin, 20-something blonde woman named Lisa Jean stands in cutoff jean shorts, a tank top, and sunglasses in the middle of a Nevada desert. In her hands is a black AR-15 rifle loaded with accessories: a forward grip, a flashlight below the barrel, an optical sight, and an odd-looking shoulder stock. With a slight smile she speaks into a camera. “Got my new Bump Fire on. Gonna dry fire it a few times to see where I can find the happy spot.”

Then, instead of pulling her finger back, she pushes on the forward grip. Though the stock stays in place against her shoulder, the rest of the gun slides forward until the trigger goes click.

That’s the happy spot,” she says. ” Let’s see if I can do it for real now.”

Lisa Jean then pops in a double drum magazine and again slides the gun forward instead of pulling the trigger, letting off a few two- and three-shot bursts. Satisfied, she turns and unloads the rest of her hundred-odd rounds into the burned-out hulk of a minivan. It takes her all of about 12 seconds.

“Whoo!” she shouts.

Though she’s firing the equivalent of hundreds of rounds per minute, Lisa Jean is not, technically, using a machine gun. What allows her AR to shoot that fast is the special stock, made by a company called Bump Fire Systems. The Bump Fire stock is an aftermarket accessory that enables semiautomatic rifle owners to replicate fully automatic fire — while escaping federal restrictions on machine guns. It’s one of a group of similar rifle stocks that are at the cutting edge of the so-called tactical market for weapons, parts, and accessories that turn firearms sold in everyday gun stores into tricked-out weapons resembling the war machines used by Navy SEALs and Special Forces.

Bump Fire stocks and others like them serve gun owners who shoot for thrill and status, not for any practical or sporting purpose. These stocks have lately become the most transgressive, showy gear in a market comprised almost exclusively of transgressive, showy gear. Many experts believe the tactical segment of the gun business has become the chief engine of growth in the industry. That’s largely due to the popularity of the AR-15, the semiautomatic civilian version of the U.S. military’s automatic M-16 rifle. Part of the AR’s appeal is its modular construction, which, more than any other firearm, serves as a platform for accessories and endless tinkering.

Nicholas Leghorn, a gun writer who reviewed the Bump Fire for the pro-gun website The Truth About Guns, told The Trace that he thinks it would appeal most to shooters who “want something to show that they’re the cool guy on the range.” According to Leghorn, that’s one of the main reasons that people buy “black rifles” like the AR-15 in the first place. He compares the rifle to another classic American toy: “The point of the AR-15 is that it’s a Barbie doll for guns,” Leghorn said. Just as Barbie fans need playsets, wardrobes, and cars to maximize their Barbie fun, so AR-15 owners need to customize their rifles to fully convey their rugged self-image.

The Bump Fire stock doesn’t convert semiautomatic rifles to true automatic fire. Rather, it provides an effective means of engaging a gun’s trigger extremely quickly. Instead of pulling back the trigger to fire, the user places his or her finger slightly in front of the trigger and pushes the whole gun forward with steady pressure. The trigger hits the finger and the round goes off. Recoil pushes the gun back, but the shooter’s forward pressure immediately returns the trigger back to the finger, and so the gun fires off another round faster than the blink of an eye.

Though an AR-15 fitted with a Bump Fire stock can fire hundreds of rounds per minute, the ATF found the add-on doesn’t turn a semiautomatic rifle into a machine gun. The devices are just this side of legal.

The thrill of what’s called “bump firing” can be had without any special attachment if the shooter simply doesn’t hold the weapon’s pistol grip, allowing the gun to rattle back and forth after each shot. But this method only works when firing from the hip, so it’s difficult to control. The Bump Fire stock, thanks to its guiding tube, can be shot from the shoulder, making it far more accurate and reliable.

A novice observer watching an AR equipped with one of these stocks go through magazines in seconds might not understand why the distinction matters: automatic or Bump Fire, don’t both fire hundreds of rounds per minute? And aren’t guns that can do that supposed to be illegal? To such questions, Bump Fire gladly provides answers, directing its customers to an exhaustive letter of approval from the Bureau of Alcohol, Tobacco, Firearms and Explosives, which examined the Bump Fire stock before it entered the market in 2012. It found that the gadget only worked as long as the shooter continuously applied forward pressure on the gun and did not alter its internal function. That means a rifle fitted with an Bump Fire doesn’t become a machine gun, and as a result is not subject to registration and taxes under the 1934 National Firearms Act, nor the 1986 ban on newly manufactured machine guns for the civilian market. The devices are just this side of legal.

The two aforementioned laws made machine guns incredibly expensive and rare, thus heightening their desirability. AR-15s can also be made to fire automatically with simple two-inch devices called drop-in auto sears, but firearms altered with such gadgets must be registered as machine guns in their own right, constraining their supply to the point where the tiny steel rectangles can fetch $10,000 apiece. Civilian-legal automatic M-16s run from $15,000 to $20,000, or about the same price as an original 1959 never-removed-from-box Barbie. By contrast, a Bump Fire stock costs about $99, while similar stocks from Slide Fire Solutions and Fostech go for $200 to $400.

Bump Fire stocks and their competitors are the latest and most effective devices in a line of sometimes infamous gadgets that make automatic firing easier. The most notorious is the Hellfire, a small metal attachment that holds the finger close to the trigger. In 1992, when ATF agents first visited the Branch Davidians’ compound in Waco, Texas, after getting reports the group was making illegally converted fully automatics, David Koresh showed them Hellfires to explain he was acting within the law. In July 1993, Gian Luigi Ferri attached these small devices to two TEC-9 semi-automatic pistols before he killed eight people and wounded six at the offices of a San Francisco law firm. (Hellfire Systems Inc, the maker of the attachment, went bankrupt the following year because of a lawsuit.)

When Senator Dianne Feinstein, a Democract from California, sponsored the early 1990’s assault weapon ban, she cited the San Francisco shooting as one of the reasons the country needed stricter gun control. In 2013, soon after the Sandy Hook Elementary School massacre in Newtown, Connecticut, Feinstein proposed a new assault weapons bill that outlawed bump fire devices or anything else designed to increase a semiautomatic weapon’s rate of fire, but that legislation never went to a vote.

Some bump fire add-ons have, in fact, run afoul of federal regulations. The first to improve on the Hellfire trigger, the Akins Accelerator, modified a semiautomatic Ruger 10-22 rifle. The ATF initially approved the Akins, but it turned out that the inventor, William Akins, had submitted a version to the bureau that worked purely on recoil — and then turned around and sold a different product that used an internal spring to aid the firing process. In 2006, the ATF banned the device, claiming it functioned like a true fully automatic weapon, with a single sustained trigger pull exhausting an entire magazine.

Bump fire enthusiasts on YouTube often laugh when they begin shooting, as if to say, Can you believe we’re getting away with this?

Some experts are puzzled over how newer add-ons like the Bump Fire stock have passed government scrutiny. Robert Farago, who runs The Truth About Guns website, wrote in 2010, with some amazement, that Slide Fire’s SSAR-15 was legal “for the rest of the day, anyway.” He called the company’s disclaimer (which said the device “does not increase the rate of fire” on its own) “disingenuous.”

These stocks are catnip for gun-obsessed YouTubers, a newly prominent group in gun circles. Many have made videos testing out Slide Fire, Bump Fire, or Fostech models, delighted with the results. Shooting one of these devices thumbs a nose at lawmakers like Feinstein. YouTubers often laugh when they begin shooting, as if to say, “Can you believe we’re getting away with this?” Bigshooterist, distinguished by his shaved head and thick-as-chowder New England accent, used a Slide Fire stock to run through a magazine loaded with 29 rounds.

“In the last 25 years that I’ve been working with [machine guns] there hasn’t been anything that really gave you something you would think was close to a full auto,” he said. “Until now.”

He said he was “blown away” with the results. Examining his paper targets, he found “29 rounds, 29 hits, all in the black.” In the words of another well-known online video personality, hickock45, “The darn thing works!”

Rob Southwick, a market analyst for the gun and outdoor industry at Florida-based Southwick Associates, said he believes that bump fire enthusiasts represent “a new kind of customer.” His company found that ARs and their accessories catered mostly to men in their 20s and 30s, for whom black rifles are not a gun they step up to after learning on a .22 – the way a Ford Escort owner might eventually graduate to a Mustang – but instead serve as their first-ever gun purchase. Southwick believes these new shooters, unlike traditional gun buyers, prefer range shooting to hunting or backyard plinking. It’s an altogether more social experience, and thus comes with hierarchies and status symbols. An AR-15, and especially an AR-15 kitted with something like a Bump Fire stock, signals to fellow range goers where its owner stands in the pecking order of coolness and bad-ass-ery.

The other thing motivating the buyers of black rifles is fear. Not so much fear of men in black helicopters coming to take their guns away — though that’s part of it — but, it seems, the fear that they won’t be able to buy an AR-15 before the party is abruptly brought to an end by stricter gun laws. The election of President Barack Obama, a Democratic, neatly correlated with a surge in AR-15 sales — making the “tactical segment” the lone area of growth in the gun industry during Obama’s first year in the White House, according to a 2008 report in the Shooting Wire, a gun industry newsletter. Southwick estimated that since 2010, the military-style rifle and accessory markets have at least doubled in value. In 2014, the market for military rifles was worth $1.4 billion, half of which was due to AR-15 sales. The market for gun parts and accessories, meanwhile, was worth $1 billion last year.

How much Bump Fire and its competitors have benefitted from this boom is hard to tell — none of the companies release sales figures, and requests for comment for this article went unanswered. A cursory glance of the websites of Bump Fire and Fostech found little in the way of marketing efforts, but Slide Fire’s slick web presence suggests it’s trying to cultivate a specific customer base. It markets its products to the self-designated Shit Hits The Fan set, who might appreciate the company’s add-ons should they find themselves besieged by hordes of zombies or post-apocalyptic gangs out of Cormac McCarthy’s The Road. Staged photos show a family of “Preppers” guarding a infant, hiding out in camouflaged tents, and taking positions behind brush. It suggests the near-fully automatic option is a necessity for those “considering the fate of [their] family in the event of a catastrophic situation.”

Some gun experts question the zombie-slaying efficacy of bump firing. In his review of the Bump Fire Systems stock for The Truth About Guns, Leghorn wrote that “the entire concept is a gimmicky toy.”

“There’s nothing you can really use it for,” Leghorn added. “It’s not reliable enough to use in a self-defense situation. It’s not going to give added benefit in a hunting situation.”

Similarly, Southwick was at pains to imagine a real use for bump fire stocks beyond the fun of shooting as many bullets as possible without the hassle of acquiring a true automatic weapon. But bump firing makes for an expensive hobby: online ammo store Lucky Gunner charges $240 for 1,000 rounds of its cheapest .223 caliber bullets, the most common round for AR-15s. If shooters using bump fire stocks can fire between 450 and 900 rounds per minute, as many attest, they could easily blow through $500 worth of ammo in less than five minutes.

With that in mind, Southwick said he sees an opportunity for gun-biz synergy: “The ammunition companies should probably be promoting these.”

[.Gif: Source Youtube]