What JDS said. This is a common error. I think cause is that the express sight is thought of more as a cosmetic accessory, to make the rifle conform to Brit or Euro style, without considering it as a practical sighting device. Also, it is easier to fit it into the middle of a short rib than to extend the rib down the barrel. In any case, the back mounted express sight is not nearly as useful as it would be further down the barrel.