Among all the sneakers, dresses, paintings, and dogs being filtered and sold through ad-hoc negotiations on Instagram, there is one outlier: guns.

A simple search on the increasingly popular photography app, which Facebook bought in April 2012 for $1 billion, reveals a web of semi-anonymous private and professional dealers who are advertising, negotiating, and selling firearms over Instagram.

Users of Instagram, which has no explicit policy prohibiting the sale of firearms, can easily find a chrome-plated antique Colt, a custom MK12-inspired AR-15 tricked-out with “all best of the best parts possible,” and an HK416D .22LR rifle by simply combining terms like #rifle or #ar15 with #forsale. These are handguns, shotguns, assault rifles, and everything in between being sold in an open, pseudo-anonymous online marketplace. With no federal law banning online sales and differing, loophole-ridden state laws, many gun control advocates are concerned about the public safety consequences of this unregulated market.

A typical gun-toting Instagram post goes something like this: “‘LWRC 10’ SBR FOR SALE!!! Come get it! Includes AAC suppressor tip, ergo grip, 3 magpul pmags, 2 40 round mags, bungee sling, and about 500 rounds of .556. Message me if interested."

The negotiation then unfolds in the comments.

"Great setup," a user says, indicating his or her interest. "Asking $3000 for everything," the seller replies. "I'm really trying to get a package deal. Don't need want to part it all out."

From there, the conversation leaves Instagram’s public-facing comments, and commences over more private channels, such as through email or a phone call, where background checks, license verifications, and age confirmations are left to the whims of the seller.

Not being a commerce site like, say, Craigslist, which has a policy prohibiting the sale of firearms, Instagram has no stated policy against gun sales. It isn’t in the business of monitoring every user-to-user conversation on its platform. Without demonstrating a clear intent to harm, or otherwise attracting the attention of the site’s community moderators, the posts are permitted to stay. Plus, while the laws around online gun sales are complicated, Instagram users trying to sell their guns really aren’t doing anything illegal.

The Bureau of Alcohol, Tobacco, Firearms and Explosives’ (ATF) authority doesn’t extend to the private sale of guns between private persons, which are largely permitted by law (as long as said persons aren’t making transactions on a regular basis). The ATF encourages the involved parties to finalize the sale through a licensed gun dealer who can run a background check, but whether or not this step is required depends on the state. While individuals are largely permitted to freely sell guns to other private citizens within their state, it is a crime to sell a firearm to any individual known to be prohibited from possessing such items (such as convicts, fugitives, and drug addicts). Federal law also prohibits so called “straw purchases,” when a buyer is purchasing the firearm from a federal firearms license holder for somebody else—as long as it isn’t a bona fide gift.

Even so, gun-control advocates—as well as some federal officials—are concerned by the possible consequences of private transactions not explicitly governed or prohibited by the law.

“We are definitely concerned about the public safety implications of unregulated online gun sales, primarily the ability of sellers to skirt background checks and trafficking in firearms—both legal and illegal guns—to prohibited persons,” says Sam Hoover, a staff attorney with the Law Center to Prevent Gun Violence, a non-profit organization dedicated to providing comprehensive legal expertise in support of gun violence prevention & smarter gun laws, who expressed an unfamiliarity with the specific firearms sales happening on Instagram.

States that have closed the private sale loophole, thereby requiring background checks and records on all gun sales, are less of a concern for organizations like Hoover’s. As are the states that require a permit for those sales. It’s when prohibited purchasers get their hands on guns from in-state, private sellers, that gun control advocates begin seeing red flags. “Private sales to in-state buyers are almost completely unregulated by federal law,” Hoover says, adding, “No background check and no record of sale are required unless state law fills this gap.”

(The Fix Gun Checks Act of 2013, would have closed the private sale loophole at the federal level, but failed to pass the Senate in an April 2013 vote. Responding to the vote, President Obama called it "a pretty shameful day for Washington.")

A spokesperson with the Department of Justice, Allison Price, said, “The Department of Justice is committed to keeping firearms out of the hands of traffickers and others prohibited by law from possessing them.”

She added, “There is no federal law prohibiting sales of firearms over the internet, and the ready availability of firearms through social applications presents yet another avenue for unlicensed sellers to transfer guns anonymously and without background checks. This loophole underscores the need for a universal background check requirement, so we can keep firearms out of the hands of criminals and other persons prohibited from having them.”

A 2011 undercover investigation commissioned by the City of New York, revealed a whopping 62 percent of private gun sellers on the Internet agreed to sell a firearm to a buyer who said he "probably couldn't pass a background check." And despite many sites’ policies prohibiting the sale of firearms (Craigslist, for instance), undercover buyers posing as illegal purchasers were able to obtain a gun in 82 percent of cases.

The 2011 report recommended that websites like Craigslist, Armslist, and Gunlistings "adopt tougher protocols to deter crime." It continued: "Websites that permit gun sales should demand transparency from sellers and buyers, facilitate reporting of suspicious behavior by site users and swiftly remove prohibited listings."

Despite a lack of federal oversight, and since Instagram doesn’t have any specific firearms-related policies, a number of Instagram gun merchants who spoke with The Daily Beast—and who all requested to be identified only by their first names—expressed a strong belief that the loosely-connected community strives to follow the relevant laws, and police itself.

“Every time I do a sale I look up the actual law,” says Mike, an Instagram user who has sold guns on Instagram and describes himself as a firearm collector, enthusiast, and small business owner, “I just Google it.”

“I can't really speak for everyone, but for myself personally it’s not worth making $10 to spend 10, 20-years-to-life, and lose my voting rights, most importantly” he says. “No amount of money is worth it. When it comes to that, I play strictly by the book.”

Danny, an Instagram user who is privately selling an AR-15 (“to Pennsylvania residents only!”—taking advantage of that private, in-state loophole), says he assumes most sellers follow the law, but acknowledges there are many ways around it. "I personally wouldn't sell illegally because I am a responsible firearm owner, and would not want to deal with or be involved with anyone who isn't," he says. Danny says he would prefer to run a background check on his potential buyer—unless the person had a permit to carry. Still, he would only ship to a licensed dealer, who would handle the transaction. If the buyer prefered to avoid that route, well, Danny says he would be reluctant to sell the firearm. “It would be a judgement call made based on their character at that moment,” he says.

But while Danny and Mike both expressed their desire to follow the law, not every Instagram user does.

In August, a Brooklyn rapper who bragged about selling guns on Instagram and YouTube, where he posted photos of firearms and bags full of cash, led authorities to the largest gun bust in New York City history, netting the NYPD 254 firearms—and 19 indictments. "It's both horrifying and comical," Special Narcotics Prosecutor Bridget Brennan said of the scheme. "They had no concept of the violence and mayhem they were causing. It was all about money." Mayor Bloomberg added, "Weak gun laws at the federal and state level have a direct and growing impact on the safety of people in our city."

Since Instagram isn’t an official retail-outlet, and certainly isn’t the only site where users can comment on others’ photographs, these legal quandaries reach well beyond the walls of the photo-sharing website. Should Facebook, which owns Instagram, ban photographs of the firearms across its platform? Should the company censor conversations around such gun photographs, banning talk of a sale or a price? One could only imagine the complicated situations that might arise if that were to happen (imagine a gun control advocate’s post getting pulled for flagged language: “This gun, which is for sale in 28 states, should be banned!”).

Americans, on both sides of the debate, would never stand for that.