Contrary to the belief that gun sales on the dark web are little more than scams or honey traps set up by the police, a new study claims firearms and ammunition really are for sale in the shadows of the web, and earn vendors over $80,000 (£62,000) a month.

The study, claimed to be the first of its kind, analysed sales from various dark web marketplaces. The sites, hidden from search engines like Google and only accessible through a special internet browser, are well-known for selling illegal drugs, stolen credit card details and computer hacking services. But until now it was believed gun sales were mostly a step too far for buyers and sellers who frequented them.

Researchers from RAND Europe, a non-profit research organisation, detailed the findings in a study called Behind The Curtain. In it, they reveal how sellers would hide guns in printers and televisions to ensure they passed through the postal service - and even traveled internationally - undetected.

One vendor, the study claims, "expressed the additional step of 'unnatural breaking up [of] guns' to pass customs" - in other words, selling several components of one gun in multiple packages to avoid detection.

In all, some 52 individual vendors were discovered by the researchers, selling weapons and accessories like ammunition, explosives and silencers. The study found 811 product listings on 18 different dark web marketplaces.

The sites' feedback system, similar to those used by eBay and Amazon to ensure the quality of products, vendors and sellers, was analysed by the researchers to confirm sales of guns were indeed taking place.

Numerous dark web marketplaces have come and gone over the years, with the Silk Road being the most infamous. Site creator Ross Ulbricht was sentenced to life in prison in February 2015 for his role as the Silk Road's administrator. Also known as cryptomarkets, these websites use cryptocurrencies like bitcoin to make payments between sellers and vendors anonymous.

The study estimates that 136 sales of guns, explosives and related products take place on the dark web each month, producing a gross revenue of around $80,000. Pistols were the most commonly sold weapon, followed by rifles and sub-machine guns. Most weapons were sent to buyers in Europe from sellers in the US. It is believed that weapons used in the 2016 Munich shooting were bought on the dark web.

While some of the marketplaces analysed by the study had rules against vendors selling firearms, some seemingly welcomed them. As the study reports: "There were 24 English/French-language cryptomarkets operating during our assessment period. Eighteen of these markets were successfully accessed and inspected. Of the 18 accessed markets, 15 had rules explicitly allowing, or not explicitly prohibiting, arms sales. Nine markets provided vendors with a dedicated 'firearms' category... while the others included firearms and related products into a general category."