The lawyer for Roy Fielding Neel Jr. entered a guilty plea in Lethbridge provincial court on behalf of his client.
Court heard that Neel's vehicle was searched in July by customs officers at the Chief Mountain border crossing south of Waterton Lakes National Park.
He had failed to declare a flare pistol, a semi-automatic handgun that was loaded and 59 rounds of ammunition.
Neel, who is 67, was fined $4,000 and faces a 10-year weapons prohibition.
His lawyer said Neel came to Canada to visit Waterton Park and has no intention of returning.