Businessman Anthony Demarco, then 62, survived, despite being wounded in the head.
The four men who appeared at the High Court in Edinburgh yesterday deny conspiracy to murder and attempted murder, while acting with an unnamed accomplice.
In the dock were Francis McGlone, 39, and Jamie Robertson, 25 – both from Paisley – and Imran Sakur, 35, and Craig Kelbie, also 35 – both from Dundee.
The charge claims that the murder plot began in April last year.
Sakur is alleged to have approached Kelbie about recruiting others to make the hit and Kelbie is supposed to have approached Robertson and McGlone, asking them to track down Mr Demarco.
Then, on 3 June last year, Robertson and McGlone are alleged to have taken a firearm to the casino, where Robertson pulled the trigger.
McGlone also faces charges under the Firearms Act, accusing him of possessing ammunition at a house in Paisley.
The trial is set to begin on 16 November at the High Court in Edinburgh.