By Christopher Mele, New York Times

A discussion group on Facebook called Texas Pew Pew Pew Show & Tell warned its users that it was intended to host conversations “about anything that goes pew pew pew,” but not to facilitate the sale or trade of firearms.

The same note asked participants to “be smart” and “to take it to PM,” a reference to private messages. “If you don’t get the hint, I can’t help stupid,” the note said.

Though the message did not explicitly tell users to talk about the sale of guns only on a private channel, those who monitor such posts said it was one of many ways that users of Facebook, the world’s largest social network, have tried to circumvent its ban on private gun sales announced in January.

Mike Monteiro, a web designer from San Francisco, helped start a campaign to monitor Facebook and report violations to get gun sales removed. Monteiro, 48, said he felt compelled to act after a gunman killed 49 people at a gay nightclub in Orlando, Florida, in June in the country’s worst mass shooting.

“I just started to search for gun sales, and sure enough, Facebook was full of them,” he said.

Some users have tried to skirt the ban by advertising other products for sale, such as baby powder or a can of Hawaiian Punch, next to rifles.

Other users did little to hide their intentions. A post pinned on a military memorabilia and firearms Facebook page recommended that those who wanted to sell guns or ammunition write the caliber and model numbers using code words, rely on external sites to share photos and make deals through private messages. The group’s moderator did not respond to a message on Facebook.

Monteiro said in the past month he reported about 500 posts or groups. Facebook took down about two-thirds of them, but sometimes only after follow-up complaints. Some of Monteiro’s social media followers joined in the effort. “If even you report 10 and one gets knocked down, that’s one less gun sale,” he said.

Monteiro is not alone in his effort. John Sibley, 41, of the Bronx, spends an average of 30 to 45 minutes a day reporting violations. He said he has been a longtime supporter of groups that seek greater gun control but felt that their approach focused mostly on raising money and seeking changes legislatively.

“If you want to do something practical, they don’t have much to offer you there,” he said. “This is an action I can take. Every time I foil a gun sale, I get a little satisfaction.”

Not everyone feels the same way, however. Sibley said he gets a fair amount of harassment on Facebook. Monteiro said a photo posted online showed a rifle pointing at a computer screen that displayed his Twitter profile. He has also been banned briefly by Facebook four times after his account was flagged several times.

Sibley said he personally has gotten 1,288 groups or posts removed in a month. He takes a screenshot of every confirmed removal notice. He also developed a detailed guide to identifying gun sales on Facebook.

Groups that operate in the open (ones with “buy guns” in their names, for instance) have been taken down, and what remain are closed, coded or secret, he said. “We’re starting to shut down the marketplace,” he said.

Still, Monteiro and Sibley described Facebook’s reporting process as a cumbersome multistep procedure that can change from day to day.

They suggested that Facebook has sophisticated software developers who could easily make the process of eliminating gun sales as automated and effective as it does in rooting out images of child pornography.

“When you want to change something, you can change it,” Monteiro said. “What all this boils down to is if Facebook did not want guns on the site, the guns would be gone tomorrow. They have the technology to do this.”

Shannon Watts, founder of Moms Demand Action for Gun Sense in America, which is part of Everytown for Gun Safety, said in a statement that she was grateful for Facebook’s response to the groups’ campaign to ban private gun sales, but that it needs to take responsibility for enforcing its own policy.

“Part of being a good corporate actor is taking ownership — lives are on the line, and it’s vital that Facebook figures this out quickly,” she said.

Facebook said any content that violated its prohibition would be removed. “We rely on our community of 1.6 billion people to help us enforce this policy by making it possible for anyone to report any piece of content including posts, photos, videos and messages,” it said in a statement.

The Facebook group Barter Junkies, which has more than 166,000 members, lost about 17,000 members after the gun sales ban went into effect, said Christopher Sullivan, the group’s primary moderator. The group facilitates the purchase, sale and barter of goods that include, among other things, cars, real estate and car parts. Sullivan said he regularly gets complaints and threats about enforcing the ban or when gun sales are removed. When he recently posted a note reminding users about the ban, the group lost 4,000 followers in four days.

Gun enthusiasts are also turning to activism. A petition on change.org that has drawn 40 of the 100 supporters it seeks urged Facebook to lift its ban. Douglas T. Brooks, 23, of Jacksonville, Florida, said he started the petition after a group he moderated on Facebook, Jacksonville Gun Traders, was shut down because it allowed members to buy, trade and sell guns.

“We were just mad because they shut us down without warning,” he said, calling the ban “kind of ridiculous.”

A secret group with a slightly different name was permitted by Facebook after it pledged to only discuss guns, he said. Still, Brooks said, he could not understand why Facebook would bar users who could legitimately own guns from buying and selling them on its site. “I would say it’s stepping on your rights,” he said.

To Learn More:

Militias Shop for Military Arms at Weapons Bazaars on Facebook (by C.J. Chivers, New York Times)

Facebook Bans Private Gun Sales, Sending Gun Traders Scrambling to Find Online Platforms (by Dustin Volz and Julia Edwards, Reuters)