I have a #1 chambered in. 17 Remington but it has been rebarreled. Ruger never offered a #1 with an octagon barrel or in rimfire. I suppose it's possible that it could be a special order. Get the serial number and call Ruger, they will be able to tell you what it left the factory as.
^^^ A scaled down #1 in rimfire calibers would seem to make a lot of sense to me. Sort of like a Ruger Low Wall, so to speak. I would think there would be a niche market for a gun like that. Call it the Ruger Number 4 and I'd be waiting in line for a 22 Mag version.