What was the claim? I haven't heard of the cartridge & a quick Google-fu didn't turn up anything.... there are several cartridges that will outrun your 6.5-06 (Which is a great round BTW
). The 6.5-06AI, 264WM, 264STW, 6.5WSM, 6.5-300WBY, 6.5AM etc.
My guess would be the Viking name may be a moniker he or his 'smith attached to a particular wildcat.
Were there any particulars given? Parent case etc?
Remember, if it look like a rat, acts like a rat, smells like a rat... it's probably a salesman! HA!