A rocket launcher and a flamethrower used in World War II are two of 19,000 weapons handed in to the Queensland government.
Police Minister Jack Dempsey announced a three-month gun amnesty in February, which ended on April 30.
People who possessed unregistered firearms were allowed to hand them in without legal repercussions.
Dempsey told state parliament on Thursday that 19,000 weapons have been handed in, including an American army flamethrower which was used to clear German foxholes in World War II.
A rocket launcher, with projectiles that can penetrate 60 centimetres of reinforced concrete, was also surrendered.
''Imagine what that would do in the wrong hands,'' Dempsey said.