The Cartel Gunsmiths
The site of a boutique arms factory raided by Mexican police in late 2014. Photo: Victor Hugo Ornelas/MOTHERBOARD


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The Cartel Gunsmiths

A homebrew gun club for a rising Mexican gang used maker-style milling tech to produce AR-15s from scratch. Was it a one-off novelty, or an omen?

It was usually evening when the three men arrived at the shop. They would roll up in a Volkswagen Beetle, and come to a halt at a nondescript, garage-sized warehouse in a strip of shops in a residential neighborhood in Guadalajara, in Southwestern Mexico's Jalisco state. They would park the Bug, and proceed to drink on the curb. Eventually the men would go inside, entering through a street door. They always locked the door behind them.


This went on for at least two months in 2014, according to a neighbor of the shop, where the men seemed to work odd hours. They never drew much attention to themselves, so there was little reason to believe their shop, located at calle Isla Trapani 2691, was in fact a sophisticated illegal gun manufacturing plant, and that the three of them were using the space to quietly produce homemade, untraceable firearms for one of Mexico's fastest-growing and violent crime syndicates.

They hid in plain sight, the homebrew gun club for a powerful new gang, the Jalisco New Generation Cartel. The Jalisco cartel has undergone such a meteoric, savage rise to power in the last few months that the head of criminal investigations for Mexico's attorney general labeled the gang a "red flag." The group is terrorizing the region with coordinated attacks on government installations. In May, Jalisco cartel members downed a Mexican military helicopter with a rocket-propelled grenade. Six soldiers were killed. The Jalisco cartel is also behind a rash of fiery roadblocks, in which cartel operatives set large vehicles and gas stations ablaze as a show of strength and to incite chaos. The cartel has been behind 39 of these roadblocks as of today; one of them, just blocks away from the site of the gang's boutique gun lab, involved a public transit bus.

Inside the shop, the men mostly made AR-15s. These air-cooled, magazine-fed rifles have become ubiquitous among Mexican narcos; they're relatively lightweight, and can take a beating. At their secret lab in Guadalajara, the three men fashioned the AR-15s from an assemblage of firearms components purchased in borderland gun shops in the US, and then smuggled into Mexico in small batches, according to officials from both countries who were interviewed for this story.


But as Mexican authorities discovered when they raided the shop, with support from American officials, on October 7, the men also milled functioning AR-15 lower receivers from unfinished blocks of aluminum. The lower receiver houses an AR-15's main firing mechanism, and by Mexican and American law is the only part of the rifle that's legally defined and controlled as the "firearm."* The men made these lowers in-house with the same sort of milling technology now embraced by a worldwide maker movement. In Mexico and the US, legal lower receivers bear serial numbers designed to make the firearms traceable. The homemade Jalisco cartel guns, being unserialized, are nearly impossible to track with a level of certainty.

Organized crime groups in Mexico have long trafficked in illegal firearms, but cartels need firepower now more than ever as they diversify their portfolios, adding oil theft, extortion, kidnapping, and human trafficking to the mix, along with drug running. Here, for the first time, was evidence of a cartel making its own firearms too. Was it just a one-off novelty, or an omen?


The lower receiver is the crux of an AR-15. It plays host to the rifle's trigger mechanism, and conjoins the stock, grip, and magazine, as well as the upper receiver, to which the barrel mounts. For a rifle like an AR-15 that has both upper and lower receivers, only the lower receiver is considered the firearm, making the rest of the gun's parts far easier to acquire and harder to trace.


The DIY gun machining process often begins with a "blank," an unfinished piece of material that, with the right tooling, can be augmented to house the actual firing mechanism. The US Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) doesn't consider a blank to be in a "stage of manufacture," which is when the firearm must be classified per the US Gun Control Act, if it's 80 percent or less complete. In other words, the blanks widely known as "80 percent lowers"—meaning they have a solid fire control cavity not yet machined with holes or divots for a fire selector, firing pins, or a trigger—are not legally considered guns by the ATF, and can be purchased off the shelf in the US but not in Mexico.

It's only once that cavity is properly machined to house a firing mechanism that the unfinished 80 percent lower receiver becomes a finished lower receiver, at which point it meets the legal definition of a "firearm" in both Mexico and the United States. It is then subject to government regulation, and must be issued and stamped with a serial number.

Amateur machinists and gunsmiths have been tooling functional lower receivers from 80 percent blanks for decades. Today, there are a few ways to do this for an untraceable AR-15: with a good, old-fashioned drill press, similar to the hand drill used in this ATF demo; with a 3D printer; and with a computer-numerical control (CNC) mill that can automatically machine an untraceable gun out of metal.


But the men weren't merely finishing the job on receiver blanks at the lab in Guadalajara. They were creating new lowers altogether.

A finished lower receiver found at the shop. Photo: Jalisco State Police

The shop was set up in a working-class neighborhood, according to Luis Carlos Najera, Jalisco's state prosecutor, who said it's not out of the ordinary to see people shuffling in and out of warehouses in this area of Guadalajara, which is chockablock with small industrial garages, workshops, and fur factories. In early June, however, when a Motherboard correspondent visited the neighborhood of the former shop, tension hung in the air. People seemed withdrawn, and were reluctant to talk about much of anything.

Today, the shop's black iron curtain is marked with gang graffiti. A trio of police officers patrol the warehouse day and night, hulking modified combat rifles at the ready. The guards said they were assigned to guard the location, but did not say what happened to necessitate them being posted there. One of the guards wrote in a notepad that a reporter had shown up, and then relayed the same message over the radio.

When Jalisco state police raided the shop, Najera said it didn't look much like a gun factory at first glance. "There wasn't much there," Najara told me. His men soon found guns, assorted raw materials (primarily aluminum) to make DIY firearms, and "some tables and other stuff."

Authorities seized a total of 18 homemade AR-15 rifles during the raid—14 guns from calle Isla Trapani 2691, and four guns from a second, undisclosed storage location in Guadalajara, where a fourth suspect, believed to be a co-conspirator in the arms ring, was arrested. (The case was bumped from the state attorney general's office to the federal prosecutor, according to Najera. The identities of the four men, who await sentencing by a federal judge in Mexico, have not been made public due to the secrecy surrounding the ongoing investigation.)


The agents also seized a big CNC mill, a common industrial machine tool that rotates on an axis while symmetrically extracting objects from larger pieces of base material. The mill was programmed with advanced software that guided the machine as it cut AR-15 lowers out of the aluminum blocks. The men would then affix the rest of the gun components to the finished firing mechanisms, which usually come out to the length of the average stapler and the width of a deck of playing cards. At some point the guns would slip out of the shop, and into the hands of Jalisco cartel members. It's believed the men also shipped homebrew arms to neighboring Michoacán state.

"My impression is that the bust that happened in Jalisco was fairly isolated"

The machine found at the Guadalajara gun lab was a CNC mill made by Hardinge, a New York-based machine tool builder known for its CNC machine tools. There was no price listing for the specific model of vertical machining center on Hardinge's website at the time of this writing, although a third party machine tool distributor has the model listed at $24,500. It's unclear who purchased the Hardinge-brand CNC mill found at the cartel gun lab, and for how much. Hardinge could not be reached for comment despite repeated requests.

It's also not clear if the men who worked at the lab had prior machining experience with industrial CNC technology, and if so, whether they were groomed internally for the job or lured to it by cartel operatives promising decent pay. A machinist familiar with CNC gun manufacturing said that operating the kind of rig found at the cartel lab would not require a lot of prior experience, though it would require some expertise. He spoke of a "boomerang effect" where the more complicated a machine gets the more capable it is—and, somewhat ironically, the more familiar the operator needs to be with it.


The CNC mill. Photo: Jalisco State Police

CNC mills like the one used at the factory in Guadalajara use digital files to chew objects out of raw materials, typically metals. Those files are often written in G-code, a basic programming language used commonly in computer-numerical machining applications. Variously known as NC (numerical control) code, G-code is what commands a computerized machine tool to make a thing in a particular way. It is hand-programmable code, meaning people can use a text editor to go through it, line by line, looking at individual coordinates and tweaking as needed. Specific NC code for untraceable guns like the ones machined at the Jalisco shop can be difficult to find, but it doesn't take much digging online to find a suitable reference model to then build on, refining by hand.

The architects behind the Jalisco shop, whoever they were, didn't necessarily need to do that kind of digging and coding on their own $20,000 machine to make guns. They could've used a drill press, 3D printer, or the Ghost Gunner, a tiny, general purpose CNC mill.

But clearly they wanted to go further. They would've been limited to finishing the remaining 20 percent on 80 percent lowers otherwise. The idea was to be able to make untraceable assault rifles in-house from scratch, machining functional lowers from blocks of aluminum. If that meant putting up thousands of dollars (assuming the labs' architects didn't just steal the CNC mill) on industrial-sized machinery and assorted costs, including skilled labor (assuming the men were paid for their work), then the resources would be spent. Money is firepower.


A crate of finished lower receivers, manufactured in-house from aluminum blanks. Photo: Jalisco Sate Police

A finished lower receiver might be what makes a gun "a gun" in the eyes of the law on both sides of the Mexico-US border. But even a firearms novice knows there's a lot more to a gun than that. Where did all the other gun parts—the stocks, grips, magazines, barrels, ammo, and so on—that funneled to the Jalisco cartel's illegal arms factory come from?

Special Agent Keith Heinzerling, of the US ATF, said we don't know because gun parts cannot be traced as they are recovered within Mexico. A serial number is required to conduct a trace via the ATF's e-Trace system for tracking recovered firearms, and gun parts, with the exception of the receiver or frame, do not bear serial numbers per the GCA. They therefore cannot be traced.

"You could surmise that [the parts] are coming from the US, since most of the weapons that come down here illegally are from the US," Heinzerling, the ATF country attaché to the US Embassy in Mexico City, told me over the phone. "But we don't have our finger on that. There's no way to trace them back."

"Keep in mind too that while we're down here we have no law enforcement authority," added Heinzerling, who helped assist Najera and Jalisco state police in taking down the lab. "We're like guests in the country. As they invite us in on certain things, we'll assist them, and vice versa. If we have information to share with them stateside, in order to facilitate investigative leads, we do that as well."


"We have an excellent relationship here with the Mexican law enforcement community. We work quite well with them."

Barrels found at the lab. Photo: Jalisco State Police

There still currently is no shortage of illicit firearms in Mexico. An estimated 24.6 million illegal guns circulate within Mexico today, and not a small number of them are sourced from America. According to annual ATF trace data for guns recovered by Mexican authorities and submitted for ATF testing, half of the guns trafficked to Mexico between 2009 and 2014 came from the US. An estimate by the Trans-Border Institute found between 106,700 and 426,729 guns were purchased in the US between 2010 and 2012, with the express purpose of being trafficked to Mexico.

"The volume of cross-border gun trafficking is very significant," said Clay Boggs, program officer at the Washington Office on Latin America.

Mexico is flooded with illegal firearms. In a market that is already so saturated with untraceable guns, it's hard to say why even the most enterprising, tech savvy cartel would want to dabble in homebrew gunsmithing. Why not simply purchase legal guns and file off the serial numbers?

"By manufacturing the lowers down here, they can manufacture them at a fraction of the cost it would take to purchase the same weapon on the open market," Heinzerling said. "And by manufacturing them there are no serial numbers at all."

Homebrew guns could also be another possible revenue stream for a cartel. As Boggs told me, "The idea of being able to manufacture your own firearms is very attractive not only because it's untraceable, but also because it's potentially very profitable and you don't have to go through the trouble of procuring them in the US or elsewhere."


And yet, it's still not easy to cheaply and reliably make firearms, Boggs said. That's why a lot of criminals in Mexico will keep relying on American guns, "both domestically manufactured and imported from Europe, for the foreseeable future." As long as those guns remain cheap and easy for criminals in Mexico to procure, Boggs told me he thinks shops like the one in Guadalajara will continue to be a rarity.

"My impression," he said, "is that the bust that happened in Jalisco was fairly isolated."


Like a lot of police raids, the one that uncovered the illegal gun lab at calle Isla Trapani 2691 happened under the cover of darkness. Few people witnessed the bust. The shopkeeper near the shuttered factory said that when authorities descended on the place that night, they entered his store and lowered the curtains.

"I went outside at 10:30 PM," said the merchant, who asked to remain anonymous for fear of gang retaliation. "But they didn't let me go."

He said the cops let him leave around 1 AM. It was only then that he realized something must not have been right about the place, although before the raid happened he said he never sensed anything was out of the ordinary. He thought the place was a run-of-the-mill machine workshop, and that the three men, all of whom he described as "young," worked nights. Every so often they would come into his store and buy stuff. If anything, he said, the three men just seemed "normal."


They liked to party. Jorge, who was restoring a car in the garage next to the former site of the illegal gun factory, said he sometimes noticed the men loosening up inside the shop. Other than that, Jorge said, "I never saw them do anything else."

One of three armed police guards who now patrol the shop, day and night. Photo: Victor Hugo Ornelas/MOTHERBOARD

It's been eight months since police raided the gun factory. A notice posted on the front of the former lab reads: "House secured by SEIDO-PGR [the deputy attorney specialized in crime investigation]. Violation of this seal incurs a federal offense." The owner of the building, who could not be contacted, changed the location's phone number soon after the October raid.

The shops next door to the busted lab have closed. Local sales are down, and no new businesses have rooted in the area. On June 11, one day before Motherboard's correspondent visited the neighborhood, a man was shot multiple times seven blocks away. The official police account is that the man was robbed, but one gang member, who lives in the area and also wished not to be named, questioned that version of the story. "Right now things are really hot," he admitted. "Do you think you need to shoot someone twice in the head to rob him?"

The lab might be gone, but the untraceable AR-15s made there aren't. Najera said that these sorts of DIY guns keep turning up at crime scenes in the region. "This makes us think that a lot of guns were already built in this factory" before the bust, he added, "and that they were already delivered to organized crime groups."


Authorities in Jalisco have recovered an additional "14 or 15" homebrew weapons on top of the 18 seized during the raid, according to Najera. All of them have similar characteristics to the guns produced in the Guadalajara shop. Najera doesn't discard the possibility that there are more illegal arms labs out there like that one, where smuggled goods and a little technical ingenuity meet with potentially deadly results. He also doesn't think joint Mexico-US arms control efforts are doing enough to disrupt the chain of events that would make illegal gun manufacturing possible in the first place.

"We need to do better tracking not only on the weapon, but also the pieces that can be used to build a weapon that are sold to a particular person," Najera explained. "If someone buys 100 gun barrels, 100 pieces of plastic, 100 butts, and 100 shipping boxes" in America, and then smuggles them into Mexico, where the parts are assembled and the lower receivers are made, "we can say that we need to open a lot of new ways for authorities to track them, here and there."

Boggs doesn't dismiss the possibility that there are more illegal gun-making plants out there, either. Mexico is already awash in cheap illegal guns from the US, "which is not to say that there aren't more cases like this," he said, "where there are individuals who have decided a more profitable approach for them."

Did the men who rode in a beater VW Bug to the shop in Guadalajara turn a profit for whomever it is they worked for? Even if they didn't, and even if their gunsmithing venture does go down as a one-off novelty, Boggs tends to think the tidal force of cross-border gun trafficking will continue drifting in favor of cartels.


"When you have that kind of volume of guns, that is so easily, cheaply, and reliably able to get from the United States to Mexico," he said, "there's not a tremendous amount of incentive to fix a system of illegal gun trafficking that, from the perspective of drug cartels, isn't broken."

No one knows exactly how many guns the men managed to make and export from their boutique before being found out. After the joint Mexico-US raid on the lab, Najera told reporters that it was believed the suspects, who were all taken into custody, produced around 100 firearms at the clandestine shop over several months. But Najera later told me that he'd been informed that the shop had the technical capacity to produce 200 untraceable AR-15s per month.

In a country where over 24 million illegal guns are estimated to be circulating today, the handiwork of a couple amateur narco gunsmiths should barely register in the ongoing technological arms race between cartels and Mexican and American law enforcement.

"I compare this to the meth labs, because if they can get the chemicals then how many of these machines can they buy?"

There is also nothing revolutionary about the technology the men used to manufacture their cache of untraceable guns; people have been milling untraceable firearms in garages for a long time. But that a cartel was dabbling in homebrew gunsmithing in the first place is enough for Najera to take pause.

"It speaks to us about how these groups have more resources every day, but also a lot about their inventiveness to evade justice at this side of the border and the other," he told me.

Mexico's cartels, Najera added, are looking to take full advantage of those resources. Success, for them, is a matter of securing power and influence through a technical and industrial cunning that goes virtually unparalleled among the world's international crime groups. That's why Mexican cartels are building citywide CCTV networks, forcing kidnapped engineers to build secret radio networks, and shipping stolen iron ore to China in exchange for bulk meth precursor chemicals. It's not a question of whether cartels beyond Jalisco can't get their hands on computerized mills to make their own guns, but how far up they're willing to scale.

"I compare this to the meth labs," Najera said, "because if they can get the chemicals then how many of these machines can they buy?"

With additional reporting by Victor Hugo Ornelas and Camilo Salas.

*Clarification: Any part, not just the finished lower receiver, that might be used to build a gun in Mexico is itself a firearm per the Federal Firearms Law. H/t Rafael Castillo

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