These are the cold faces of the criminals behind Bristol's most dangerous drug dealing network.

For the first time the Evening Post can report how they were behind cocaine rings – some of them armed with rifles, handguns and even grenades.

Already in the past two years 17 men and one woman have been jailed for a total of more than 100 years after being busted by Avon and Somerset police's Atrium drug crime unit. But the details of their criminality were made secret by court orders imposed to prevent related trials being compromised.

Yesterday, after 20 hours of deliberation at Bristol Crown Court, a jury found former Olympic judo competitor James Waithe guilty of possessing firearms with intent to endanger life. He had already been found guilty of conspiring with four other men to flood the streets with cocaine from the gang's base at a flat he owned in Highridge Green.

It marked the end of the final trial in a series of cases which can only now be made public, lifting the lid on the city's most prolific drug networks. The five men convicted after a case code named Operation Malbec by police join the 18 other criminals already in jail. They are former school teacher Waithe, 47; Craig Rodel, 46, of Wexford Road, Knowle; Grant Richmond, 29, of Long Cross, Lawrence Weston; Luke Downes, 22, of Pevensey Walk, Knowle, and Robert Brooks, 63, of no fixed address. They face hefty prison stretches when sentenced next month. Their Class A drugs factory was capable of making as much as £1 million per week and it could have raked in £50 million in total.

The gang were armed with three military-issue stun grenades, four rifles, five handguns, a shotgun and ammunition, which were used to protect their empire. Waithe, Rodel, Downes and Brooks have firearms offences to their names as well.

Detective Superintendent Arthur Lewis, of Avon and Somerset police, said: "It was very unusual to find this level of weapons in Bristol – unprecedented I would say.

"These were very serious offences. The investigations, which have gone on for nearly three years, have been complex and difficult."

"Throughout the inquiries we have been very grateful for the level of support we've received from witnesses, local residents and local communities.

"We will continue to be relentless in pursuing, prosecuting and bringing to justice people who will commit offences of this nature."

DS Lewis believes the 100 years in jail sentences already passed by the courts – and the sentences the latest gang will get next month – will make a massive difference in the fight against drug dealing.

He added: "It will have a significant effect on removing the threat that these organised crime groups posed to the local community, not just in Bristol but across the South West.

"I think the volume of acquisitive crime committed by drug addicts, for example, is always affected when you arrest those who supply class A drugs."

As previously reported, Rodel and his gang were caught when police were called to a burglary in June last year at flat 7, 79 Highridge Green. Debt-collector Waithe, who competed for Barbados in judo at the 1988 Seoul Olympics and represented England in the Commonwealth Games, denied knowing there were drugs and weapons in the flat he rented to Rodel for £2,000 per week.

Waithe was cleared of six firearms offences but found guilty of possessing firearms with intent to endanger life.

Unusually, key evidence in the trial of Waithe and Brooks was given by Richmond, who turned supergrass.

Rodel, the ringleader of the enterprise that took over the drugs market when another gang run by the Pearce family were jailed in 2007, is also believed to have been a police informer in the past.

DS Lewis said: "Part of our approach is to utilise all available resources, skills and legislation as best we can. Part of gathering intelligence allows us to reward people who come forward with information and intelligence which we can build investigations on."

Senior district crown prosecutor from Crown Prosecution Service, Sian Sullivan, said: "This large-scale drug-dealing operation was run like a business and while it may have been a profitable business, it was an illegal one. Drug dealing, with its associated violence and use of weapons by its practitioners, causes misery and erodes the fabric of our society."

Judge Simon Darwall-Smith is awaiting pre-sentence reports before sentencing next month.

Anyone with any information about the supply of drugs can contact police on 0845 4567000 or Crimestoppers on 0800 555111.