While the Mounties refused to comment on an ongoing investigation, several gun retailers across the country told the Canadian Broadcasting Corp. they had been visited by officers about the guns.
The broadcaster said it appears at least 14 months ago, the Canadian Border Security Agency had inspected and approved the importation of the guns, which feature real wood and steel.
Border security officials said they were trying to track the documents related to the shipment.
Retailers told the CBC there were fears the BB guns could be converted into a real semi-automatic assault rifle by replacing the barrel and bolt.
One online retailer in British Columbia has been selling the guns for as much as $299, calling them "more like a real AK-47 than it's like a BB gun."
Toronto-area hobby store owner Tony Messina told the CBC officers handcuffed him last week during a search of his store and confiscated two of the guns.
"The [CBSA] should have checked things out before they actually allowed them to be sold," he said. "Somebody messed up.
It wasn't immediately clear how many of the replicas were imported.