Detective Senior Constable Daniel Jacuta told Melbourne Magistrates Court on Tuesday that when police raided unemployed bricklayer Sam Grace's apartment they found a black starter's pistol allegedly used in the robberies hidden in a tissue box in his bedroom.

Senior Detective Jacuta said police also found a drug ledger where Mr Grace had written down all the drugs he had bought and how much he owed.

Mr Grace, who appeared in court for a bail application, is charged with committing seven armed robberies in Melbourne's north-west between September 15 and 26 last year and possessing a firearm and ammunition.

Senior Detective Jacuta said two of the armed robberies, including one on a Coburg sex shop, involved a co-offender armed with a single-barrelled shotgun. The co-offender has yet to be arrested.

In opposing bail, Senior Detective Jacuta said the seven armed robberies involved crimes on soft targets where people going about their business were threatened at gunpoint to get money to support Mr Grace's serious drug addiction.

The detective said when Mr Grace was arrested on October 10 at the Hadfield apartment he shared with his 18-year-old girlfriend, Shylah Rodden, a black starter's pistol he had allegedly used in the armed robberies to threaten staff was hidden in a tissue box in his bedroom.

Police also found the drug ledger and clothes identical to the ones worn by the armed robber.

One text message allegedly sent by Mr Grace to his girlfriend claimed he did not want to get arrested but "I'm smart with robs".

Mr Grace's father, Darren, told the court he was stunned and in disbelief when he found out his son had been arrested and charged with seven armed robberies.

Mr Grace said he spoke to his son after his arrest who told him he had been an ice addict for three years. His son claimed his drug addiction was "killing me".

Mr Grace's son had moved out of home and was living with his girlfriend for six months before his arrest and his family had had no idea he was using drugs.

The family wanted Mr Grace released so he could attend a drug rehabilitation centre.

His girlfriend, Ms Rodden, who is alleged to have carried out surveillance on the Coburg sex shop before it was held up on September 26, has been charged with armed robbery and possessing a firearm and ammunition.

Magistrate Simon Garnett granted bail but with strict conditions, including that Mr Grace report daily to Frankston police station, stay at a drug rehabilitation clinic, surrender his passport, not leave Victoria, not contact any prosecution witnesses and not use drugs.

Mr Grace will appear in court again next month.