In the past month, John Sibley has been responsible for the takedown of more than 1,000 Facebook groups selling guns. He and others are part of a ragtag social media militia of sorts they say are trying to fill a gap in Facebook's gun ban.

They spend their free time reporting private gun sales that still permeate the social network months after Facebook banned the deals. And there are a lot of posts to report. While Sibley's personal tally is on the high side, Mashable spoke to others who flag dozens, even hundreds per week.

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What shocks them is how easy it is to find sales and the jaw-dropping number out there. For them, Facebook's ban has rung hollow.

"That announcement in January feels like a pure PR move," Sibley, a New Yorker, who started reporting the sales after the Orlando nightclub shooting said. "It doesn’t change anything, just gets them some good press."

Sibley and others share their victories — and frustrations with Facebook's enforcement — on Twitter, sometimes in the form of screengrabs marking the groups or posts they got removed that day.

Another 42 FB groups dealing guns reported and removed today for a personal total of 1015. Cc: @monteiro #ReportGate pic.twitter.com/bjn9JHHYOI — John Sibley (@jbsibley) July 9, 2016

It's a way to attract more people to the cause — most of those flagging sales know of each other solely from Twitter — and to shame Facebook into policing their own site. With all its engineering power, they ask, why can't Facebook build an algorithm to target sales? Why can't it sic its employees on offenders without prompting?

How Facebook responds

Facebook generally relies on users to report noncompliant content — not just gun sales — with a few exceptions, such as child pornography and extremism, for efficiency, a company representative told Mashable. Creating an algorithm that targets gun sales could cause several layers of problems, one being that general search terms could capture lots of posts beyond sales that are acceptable under Facebook's standards.

"There is a lot of debate and discussion around firearms that is perfectly allowable and permissible on Facebook and that includes the sale of a new model," the representative said. It's the actual arrangement of a sale that's not allowed, they said.

Beyond that, one could argue that if Facebook made algorithms to crawl its site searching for noncompliant posts, non-offenders, particularly privacy advocates, would be complaining, too.

"We do have content up on Facebook that violates most of our policies at any given point," the representative said. "It's not unique, in that perspective, that this relates to our gun policies. This is why we have people reviewing reports around the clock."

Closed group. Individuals only. Clearly advertising sales. Reported multiple times. Facebook says it’s ok. pic.twitter.com/9JTckM9e84 — Mike Monteiro (@monteiro) July 14, 2016

Facebook gets more than 1 million reports of noncompliant content a day and has a team reviewing the flagged content 24/7. But power-flaggers say not all reports are responded to correctly. Some members of the Twitter army say they report groups and Facebook says it will take them down, but they linger for days, even weeks.

@facebook says they removed a group I reported, its still up after two weeks... @monteiro pic.twitter.com/LAcMgTfwqQ — David A Buchanan (@DavieB) July 14, 2016

Generally, Facebook takes approved content down quickly, but if something doesn't get removed, it could be a glitch, the representative said. It's also possible that Facebook removes an offending post within a group, but not the entire page. Or a reported group doesn't violate the policy, like those set up by retailers. The ban only impacts private sellers.

Getting blocked and harassed

But power-flaggers find Facebook's excuses frustrating. And when their reporting abilities get frozen — sometimes for 24 hours and at least one person reported a 30-day block— for reporting too often, it is like salt in a wound. Facebook automatically suspends users caught by anti-spam protections. There isn't a magic number that will get you frozen out, but a rule of thumb adopted by the Facebook flaggers is to report five, break for five minutes, then pick it up again. Sibley even wrote a how-to post on Medium to lay out best practices.

But it's not just frustration with Facebook that can get the social media militia down. They face a deluge of online harassment. Many have been doxxed and sent death threats on social media. Some people Mashable spoke to didn't want to share their names because they feared the intimidation.

Pro-gun users against the reporting even started a hashtag, #reportgate, according to Sibley, but the Twitter militia started using it to share their screengrabs and find more likeminded users.

After the sad events this week, I chose to spend my Saturday morning reporting gun sale/trade groups and posts on @facebook. #ReportGate — Joel M. Solomon (@joelmsolomon) July 9, 2016

Hidden sales

Secret groups are hard to crack, but individual dealers can make public posts difficult to find too by using code.

They disguise their listings with obscure terms like pew pew, molon labe ("come and take them" in Latin), or EDC (everyday carry). Some go so far as to disguise a gun sale within a photo.

David Buchanan, who started flagging posts a few weeks ago, says he's spotted several. "One said 'I’m selling this shirt, comes with everything in the picture,' and in the picture is a gun with magazines and ammunition."

The Utah web developer tries to take 10 minutes per day before work to report sales. He first found out about the practice on Twitter.

"I didn't really know if it was that big of a deal, then I checked a page that was nearby where I live and a guy was selling a handgun with a silencer and a magazine for $500. It was in a yard sale group, which is common," he said.

Despite shortcomings, the reporters still believe they are making a difference. Their logic is that since private sellers don't legally have to do background checks like retailers, people buying guns on Facebook are more likely to be ones who don't want to be traced. And the more sales they stop, the better.

Many of the reporters were inspired to start flagging gun sales after the Orlando shooting. Then when it was reported this week that the Dallas shooter bought an AK47 on Facebook, it galvanized them even more.

"I’m not on the front lines of legislation but at least I’m doing something to make it a little harder [to sell guns on Facebook] and helping to galvanize people who feel the same way," Sibley said.

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Editor's note: July 16, 2016, 11:51 a.m. EDT This story was updated to include additional comment from Facebook.