But Mark Anthony Munro, 53, has managed to convince the Court of Appeal to shave three years from his sentence for the planned hold-up of the Chubb security van.

It is now almost a decade since Munro, of Campbell, and another man robbed the armoured van in broad daylight outside the Mawson Club in May 2004.

The pair had been recruited to carry out the heist, which involved an inside man and a mastermind who gathered intelligence and planned the crime.

Munro and his accomplice waited outside the club at a bus shelter, before approaching the security guards as they were leaving.

The accomplice, armed with a pistol, demanded they hand over cash bags.

The pair managed to take roughly $151,000 from the guards.

During the hold-up, Munro shot security guard Kevin Matangi with a shotgun.

Pellets were sprayed across his face and chest, a dozen of which were still lodged in his body last year.

The robbers were eventually tracked down by police and Munro was brought before the ACT Supreme Court for trial last year.

Munro was found guilty by a jury and sentenced to 18 years prison with 13 years non-parole by Acting Justice John Nield.

But he appealed both his conviction and sentence for the crime in the ACT Court of Appeal.

A full bench heard the appeal late last year, and judgment was delivered on Thursday.

All three judges - Justice Hilary Penfold, Justice Richard Refshauge, and Justice John Burns - dismissed his appeal against conviction.

But Justice Refshauge and Justice Penfold found his sentence should have three years cut from the head sentence and the non-parole period, reducing the total to 15 years.

It means Munro will now be eligible for parole in eight years time, in December 2022.