A man who ordered parts for a kite buggy was shocked when he received two Winchester rifles instead.
A new order has been placed for the kite buggy parts
Andy Coptcoat, from Berkshire, ordered two steel tubes through Bristol-based Atmosphere Kites, who forwarded the order to its suppliers in France.
"I thought the shape of the package looked strange and when I checked it, the two firearms were inside," he said.
A spokesman for carrier Business Post, blamed human error, saying there had been a mix-up with labels.
Mr Coptcoat, 34, took the guns to Reading police station, but said he was horrified they could so easily be sent through the post.
"They were shipped in cardboard boxes and not secured, I could've been stopped by the police or the car could have been stolen and the guns fallen into the wrong hands," he said.
Alistair McHardy, from Atmosphere Kites, said: "The parts still appear to be stuck on the French side, but we've placed a new order. The guns were apparently meant for a dealer.
"It's worrying that there's little control over moving dangerous weapons round."
A spokesman for Business Post said: "The operator concerned with the error in question has been retrained to ensure he understands fully the possible consequences of such errors.
"We have also informed the French distributor that consignments of firearms will not be accepted for delivery in future."