Defending champion Stuart Rendell started as a big favourite, but Jones took control early and had already assured victory when he launched the biggest throw of the evening in the sixth round.
His mark of 72.55 was comfortably further than that of silver medallist Philip Jensen from New Zealand, who recorded 69.48.
Head was not far behind in third spot and his throw of 68.60 pushed Rendell out of the medals.
A delighted Jones, who won silver at the last Games in Kuala Lumpur in 1998, admitted his surprise after the win.
"I said Stuart Rendell was favourite if he got a big one out, but he didn't and I took advantage.
"I'm worn out - I've only gone and won."