The significant drug dealing ring would use baby gum numbing powder to cut the cocaine, the former dealer said, increasing the drug's volume and the group's profit by 50 per cent.

He said the head of the drug ring would receive the product before cutting it and selling it to other dealers lower down the chain. Those dealers would probably cut it further, he said.

At its height between 2015 and 2017, the Canberra drug ring was pulling in tens of thousands of dollars a week.

It sold cocaine and cannabis, as well as methylamphetamine and ecstasy to other dealers lower down the chain who would deal the drugs on to their own customers.

He said the drug ring would sometimes hand the merchandise to its customers on “tick”, meaning they would not have to pay for the drugs until after they had sold them.

But in 2017, the risks of such an arrangement were made clear when one of the drug ring's customers was raided by police, the court heard.

Officers seized thousands of dollars worth of drugs and cash.

Prosecutors say the head of the drug ring grew under immense pressure from his Sydney suppliers to pay significant drug debts.

It’s alleged that the man called on an old school friend Javarne Saipani, 25, to standover a drug dealing colleague to chase debts from lower down the chain.

Mr Saipani is accused of threatening to blow his legs off with a shotgun if he did not come up with the money.

He has pleaded not guilty to a charge of threatening grievous bodily harm.

The colleague, the alleged victim, gave evidence at Mr Saipani’s ACT Supreme Court trial on Tuesday.

He told the court that the head of the drug ring had a lavish spending habit and a gambling problem.

“The poker machines, he couldn’t get enough of them.”

The alleged victim told the court that the head of the ring put his own drug debts onto him.

He admitted he had wasted $1.5 million of his own profits in three years on clothes and getting around town.

He said the Canberra drug boss ordered him to rob a “stash house” to help pay the debt, but he refused when he found out the house was connected to Nomads bikies, and it would be suicidal.

The man agreed, under questioning by defence barrister James Stewart, that Mr Saipani was never involved in their drug dealing business.

Mr Stewart suggested Mr Saipani had only got involved when his childhood friend, the drug ring leader, was threatened by Sydney people who said they would put him in the ground.

The witness said the drug leader made up allegations he had been bashed to increase the pressure on him.

The barrister also suggested that Mr Saipani had never threatened the alleged victim but had only hurried him up to collect the debts owed, and that the threat was coming from Sydney.

“He told me he was going to take my leg off with a shotgun sir, that’s a threat,” the alleged victim said.

The alleged victim also denied that Mr Saipani had never produced a shotgun, and denied that he made the firearm up to make the threat appear more serious when asking his brother to take out a loan.

He said he was only smoking cannabis at the time, and denied the drug was a hallucinogen.

When asked by Mr Stewart how he knew that, he said "the internet, researching".

The trial continues.