The national gun control lobby wants more resources put into finding dangerous weapons hidden in the Tasmanian community.
On Monday police in Devonport seized a semi-automatic assault rifle and other unregistered firearms from a local property.
Only a few assault rifles have been seized in Tasmania since they were outlawed after the Port Arthur massacre in 1996.
Detective senior sergeant Joanne Stolp says police believe there are more in the community.
“They have just never come to light because either searches haven’t been conducted or people have forgotten about them lying around,” she said.
Roland Browne from Gun Control Australia says police need more resources to find the guns.
“They are liable to be stolen, we can’t rely on people handing them in,” he said.
Police say no semi-automatic rifles have been used in crimes in Tasmania since 1996.