The owner of High Bridge Arms didn’t publicly offer a reason for shuttering San Francisco’s last gun shop in late 2015, but the move was widely viewed as a symbol of political defeat.

In one of the most liberal cities in the country, and with increasingly burdensome state gun laws, the business of selling firearms had apparently become too exhausting.

At the time, then-Supervisor Mark Farrell had just proposed an ordinance that would add more oversight on gun and ammunition sales.

“From my perspective, if the last gun store in San Francisco wants to close its doors because of my legislation, so be it,” he said in an October 2015 interview.

But records recently released by the federal Bureau of Alcohol, Tobacco, Firearms and Explosives show there’s more to the story than many — including Farrell, now San Francisco’s mayor — realized.

Just months before the closure, ATF officials found that High Bridge Arms had violated 10 federal gun laws, including allegedly selling a firearm to a prohibited possessor and failing to record the sales of 71 guns.

An ATF operations director agreed it was best to revoke the dealer’s license “due to the numerous, repeated serious violations of the Gun Control Act.”

The report was part of a trove of documents recently released to the Brady Campaign to Prevent Gun Violence after the advocacy group sued the ATF for records. The Brady Campaign shared the reports with The Chronicle.

The Brady Campaign has not yet received all of the reports, but those released to date offer a window into ATF operations, which are heavily guarded by federal laws.

Records show that ATF inspectors recommended revoking at least six federal gun-selling licenses in Northern California from 2014 to 2016. The reports list a range of alleged violations, including missing records on firearm sales, attempts to sell prohibited firearms, and selling a gun to a known, violent felon.

It’s unclear exactly what happened after these recommendations. A spokeswoman for ATF said she couldn’t comment on whether the findings resulted in license revocations.

Four of the six Northern California gun shops closed in the months after the inspections, but two others, in Sacramento and San Bruno, remained open after an ATF manager reversed the agency’s own revocation recommendation, records show.

The Tiahrt Amendment, a federal law that prohibits ATF from releasing gun-tracing data to the public, makes it nearly impossible to know whether any of the guns sold by these companies were used in crimes.

But Avery Gardiner, co-president of the Brady Campaign, said the reports shed light on how illegal firearms could be purchased directly from licensed dealers.

“The reason it’s easy to get a gun legally on the street is that a small percentage of gun dealers are operating badly,” she said. “Almost all the guns used in crimes were initially part of the lawful gun industry, and they were diverted. Sometimes that isn’t detectable by gun dealers — but often it is.”

In San Bruno, the owner of Peninsula Guns & Tactical was cited for failing to log disposition records and acknowledged a “willful effort to circumvent state firearm laws” to sell prohibited weapons, records show.

An ATF inspector recommended revoking Peninsula Guns’ license, but a director later canceled the revocation based on “the testimony of witnesses and circumstantial evidence provided by the licensees.”

A woman who was working at Peninsula Guns on a recent day, and who described herself as one of the owners, told The Chronicle that they had taken over the space from a previous owner and that ATF had falsely conflated the two groups.

She said the violations — which came after an ATF inspection that occurred between June 2013 and June 2014 — stemmed from the previous owner. She declined to give her name.

Other Northern California violations noted in ATF reports from 2014 implicated a dealer in Marina (Monterey County), referred to as FMI 14: Manzanita Group, which “willfully distributed a firearm to a prohibited violent felon” through the felon’s spouse; and a Ukiah licensee, referred to as N.W.E., which allegedly failed to report multiple firearm dispositions and had a “high volume” of guns traced to suspects in a drug probe.

ATF inspectors recommended revoking both of the licenses. Businesses now in the same locations no longer sell firearms.

In Sacramento, Just Guns remained open after an inspector initially recommended its revocation in 2016. The dealer repeatedly failed to maintain accurate acquisition and disposition records, according to the ATF, but the revocation recommendation was later overturned in lieu of a warning conference.

The store’s Facebook page indicates it’s now closed for remodeling, and attempts to reach the owner were not successful.

The ATF inspected 11,009 federal firearms licenses in 2017, or about 8 percent of the nearly 135,000 issued throughout the country. The inspections resulted in revoked licenses for less than half of 1 percent of this total.

Craig DeLuz, a spokesman for the California Association of Federal Firearms Licensees, said gun dealers by and large follow the law, with violations mostly relating to minor record-keeping issues.

“The inspections are highly burdensome, but we also believe that they are necessary,” he said.

The legal standard to revoke a license is to show willfulness in violating gun-dealing laws, said Alexandria Corneiro, a spokeswoman for ATF’s San Francisco field division.

“In order to prove willfulness, ATF must show that the licensee was plainly indifferent or purposely disregarded the required laws and regulations,” she wrote in an email.

Corneiro said the ATF’s goal is to maintain “voluntary compliance” with the laws and regulations of the Gun Control Act. “We go to great lengths to ensure that the FFL (federal firearms licensee) is exposed to as much information as they need to properly and legally conduct firearms transactions,” she said.

A recent New York Times report, also based on the Brady Campaign records, found that ATF officials across the country have been lenient on gun dealers after they’ve committed serious or repeated violations, regularly overturning inspectors’ recommendations to revoke licenses.

Gardiner suggested the federal government should follow its own rules and enforce the laws that govern gun sellers as well as gun owners.

“There are a small number of gun dealers putting profits over human lives,” she said. “And they should be shut down if they won’t reform.”

Megan Cassidy is a San Francisco Chronicle staff writer. Email: megan.cassidy@sfchronicle.com Twitter: @meganrcassidy