The Police Association is concerned there are still firearm dealers advertising guns for sale that could soon be illegal under new legislation.
This morning the Gun Supplies website was advertising an MSSA semi-automatic shotgun and a semi-automatic rifle that can take glock pistol magazines, which can hold 17 or more cartridges.
Both were discounted.
Police Association president Chris Cahill said any firearms like these bought now would not be eligible for the buy back scheme.
"You'd have to wonder why someone would be spending their money now knowing that it's money down the drain.
"We would argue why would a business continue to promote this, and they should look at their ethics and see really if that is the sort of business they want to be running."
He said it was possible people would buying them now for illegitimate purposes.
Gun Supplies owner Don Perry refused to comment. He then deleted the listings from his website.