Merchants from Fronteras, Sonora, gave the man a wad of money to spend on guns and ammunition in Douglas and smuggle them back south.

Working with an accomplice, Manuel Inez bought the armaments, then stashed them in a hiding place east of Douglas and headed across the border. But he was arrested and jailed in Agua Prieta.

"Inez' confederate succeeded in removing the arms from the cache, and after a brush with line riders escaped south with $1500 worth of guns and cartridges."

The year was 1910, the story from the Dec. 4 edition of the Arizona Daily Star. That year and for years to come, as the Mexican Revolution flared, the Star was studded with stories of gun- and ammunition-smuggling to Mexico.

This history came to mind when I read a recent report attempting to specify the number of guns trafficked from the U.S. into Mexico and establish the profits to gun-sellers. The estimates are mind-blowingly - and suspiciously - high: 253,000 U.S. guns shipped to Mexico annually, 2010 to 2012, worth about $127 million per year.

That would mean U.S. and Mexican authorities seized only about 15 percent of the smuggled guns at the border.

For the years 1997-1999, the study estimated 88,000 guns trafficked per year, producing revenue of $32 million per year.

The Operation Fast and Furious scandal brought gun-smuggling to Mexico into the American's public's consciousness. But around here trafficking guns to Mexico is as old as the border. And so is the fact that American sellers make money off the deals, consciously or not.

For me, the value of the study, "The Way of the Gun," is not so much in the estimates it arrives at but the old dynamic it explores.

March 15, 1912: "President Taft tonight signed the resolution making it unlawful to export arms and ammunition to any American country where domestic violence exists and immediately after that issued a proclamation declaring that since domestic violence exists in Mexico, all federal officers are enjoined to prevent violations of the resolution."

The Way of the Gun uses a novel, complex method for estimating the number of guns crossing the border. Unlike almost all similar studies, it doesn't start with the number of weapons seized at the border.

Economic geographer Topher McDougal, an assistant professor at the University of San Diego, led the study and tried to explain the methodology to me by phone Friday. Its use of statistics is beyond my grasp, but it takes the number of federally licensed firearm dealers and their distance from the border, controlling for many other factors such as population, to estimate demand from Mexico.

Then it uses Bureau of Alcohol Tobacco Firearms and Explosives estimates of firearms sold in certain years to extrapolate guns sold and the amount of money sellers are making on guns destined for Mexico.

Perhaps the study's most controversial conclusion: "The traffic represents a major source of revenue for U.S. domestic firearms retailers, without which roughly 37 percent of FFLs (federal firearms licenses) would cease to exist."

I asked Carlos Canino, the assistant special agent in charge of the ATF's Tucson office about the study. Canino came to Tucson after Fast and Furious, from a job as ATF attaché at the U.S. Embassy in Mexico City. There, he said, he heard estimates as unrealistically high as 2,000 guns a day going into Mexico from the United States.

"You can't accurately quantify the unquantifiable," he told me Friday. But he appreciated the researchers' effort, saying the number of trafficked guns is "a million-dollar question that everyone wants to know the answer to."

What's clear is that the relatively open gun laws in the United States combined with the strict ones in Mexico create a natural, mostly black-market flow.

Oct. 3 , 1912: " Douglas, Ariz - A shipment of fifty cases of Winchester rifles of the model of 1896 and 100 cases of 30-30 high-power cartridges was received by Wells Fargo & Co. express here Sunday afternoon and delivered yesterday afternoon to Mexican Consul Cuesta. The arms are presumably for use in equipping more volunteers for the service of the state of Sonora."

As you might expect, gun dealers strenuously dispute the study's findings.

"Their methodology is flawed, their conclusions are patently absurd and offensive," said Larry Keane, the senior vice president of the National Shooting Sports Foundation, a firearms trade group. "The assertions by these academics are laughable and insulting to law-abiding firearms retailers throughout the Southwest who cooperate daily with ATF."

He pointed to an ATF document obtained in an ongoing lawsuit, which shows that the guns seized in Mexico between 2006 and 2010 and traced to the United States were on average 15 years old. If hundreds of thousands of new guns were being sent annually to Mexico, the seized guns would be newer, he said.

But while Keane also objected to the idea that gun-sellers are profiting from trafficking to Mexico, it's inevitably true in this area that some do. They may not be intentionally selling guns and ammunition to traffickers - and the flow McDougal estimates may well be exaggerated - but it happens regularly anyway. Perhaps the revenue generated annually wasn't $127 million but was $54 million, the low-end figure in the study.

Around here, some people legally buy guns then illegally send them on to Mexico. It's a part of the culture and has been for more than a hundred years.

January 12, 1918: "Nine Yaqui Indians, captured yesterday by an American cavalry detachment in Bear Valley west of here, told army intelligence officers today they obtained their arms and ammunition before an embargo was put on their exportation. Army intelligence officers said they believed the Yaquis had been making regular trips to Tucson, carrying ammunition back to their tribal headquarters in Sonora, Mexico."

Contact columnist Tim Steller at or 807-8427. On Twitter @senyorreporter