what really happened

The events of this film are very very loosely based on Chicago mobster Joseph 'Dan' Testas 6 week visit in 1971.
The trip was to arrange a business deal with the Mister Big of Sydney crime - Lenny McPherson. The business was the purchase of American slot machines, built by a Mafia controlled company.
The hunting trip occuring during Testas 1969 visit, and they really did use M16s.
The Americans were not opposed but welcomed with open arms.