A NSW man has been jailed for at least 31 years and one month after he shot dead his estranged wife in front of his daughter in a “chilling and deeply shocking” crime.

Keith Owen Goodbun last year pleaded guilty to murdering Molly Goodbun, 59, assaulting his daughter, contravening an apprehended violence order and using an unregistered firearm in Maitland in 2016.

In the NSW Supreme Court on Wednesday, Justice Helen Wilson sentenced the 62-year-old to 41 years and six months in prison with a non-parole period 31 years and one month.

“The murder of Molly Goodbun was a chilling and deeply-shocking crime,” the judge said.

“It may, without hyperbole, be described as an execution.

“It was clearly his intention that nothing would stop him from murdering his wife.”

Goodbun shot his estranged wife four times after he arrived at their former marital house in the early hours of October 7, 2016, despite efforts by their adult daughter to intervene.

Bionca Simmons tried to wrestle away her father’s gun and provide first aid to her fatally wounded mother, asking her to “just stay with me till we get help here”.

She ran to a neighbour’s place when Goodbun told her to “get the f*** out of here or you’re next, you’re lucky I haven’t done it already”. Goodbun will be 91 when he’s eligible for parole.