I can't say for certain that it is bad information, just that I have never heard of one. Perhaps it was a typo or some such mistake.
There were two models of this revolver which I am familiar with. The original was the Model 640, a five-shot, hammerless, .38 Spl which was a very good-looking firearm IMHO. It changed to the Model 640-1 which was rated for .357 Magnum. I have one of these and I highly recommend it, but with .38 Spl ammo.