Gang leader Farhad Qaumi has been jailed for at least 43 years for his role in the fatal 'violent underworld rampage' that erupted in western Sydney in late 2013, and his two brothers have received shorter but significant terms.

The 34-year-old Brothers 4 Life Blacktown chapter leader was jailed on Friday for a string of crimes including manslaughter and a contract murder and Mumtaz Qaumi, 32, was jailed for at least 36 years for offences including the two fatal shootings.

Describing the violence as 'outlandish and lawless', Justice Peter Hamill also jailed Jamil Qaumi, 25, for at least 21 years for his crimes, which included manslaughter.

Brothers 4 Life Blacktown chapter leader Farhad Qaumi (pictured) will spend at least 43 years behind bars for a string of violent crimes, which included including manslaughter and a contract murder

Farhad's younger brother Mumtaz Qaumi (pictured) has been jailed for at least least 36 years for offences including two fatal shootings

Farhad Qaumi was sentenced for 15 offences including the December 2013 contract murder of debt collector Joseph Antoun at Strathfield and the October 2013 manslaughter of Mahmoud Hamzy at Revesby Heights.

In setting a maximum of 60 years, the judge said Qaumi was the 'undisputed, and feared, leader of the B4 Blacktown' who, more often than not used others to do his bidding.

'There was evidence he aspired to 'take over Sydney'.'

Mumtaz Qaumi received a maximum of 50 years, while the youngest brother's maximum was 30 years.

All three brothers were found guilty by a jury of numerous offences related to five shooting incidents that took place between October 28 and November 28, 2013.

'One person was killed, several others were injured and the lives of at least 10 people placed in jeopardy,' the judge said.

Joseph Antoun (left) was murdered in December 2013 at Strathfield and Mahmoud Hamzy (right) was killed in Revesby Heights in October 2013

Farhad Qaumi was the gang leader of the Brothers 4 Life Blacktown chapter

Farhad (pictured) was described by the judge as the chapter's 'undisputed, and feared, leader'

The shootings occurred in the context of 'differences' between the B4L Blacktown and a rival group called B4L at Bankstown, led by Mohammed Hamzy.

Mahmoud Hamzy was shot dead after the shooters mistakenly believed he was his cousin, Mohammed.

Justice Hamill heard the murder trial relating to Mr Antoun without a jury and found the two eldest brothers guilty of the crime on the basis that they hired the hit man.

While the murder was not part of the 'war' between the criminal gangs, the judge said he drew the inference he was approached to organise the killing because of the reputation for violence he had earned in the criminal underworld.

He also 'had a capacity to direct others to carry out murderous acts of gun violence'.