I've seen several in service myself. Less than a dozen though. Once in Gagetown an NCO brought one to me and asked what this was all about and he had one slotted but with the new slide and no tangent. I remember one in the Canadianicon Scottish regiment that had the slot filled in with weld. Same question there. No tangent sight. Others on another gun forum have also mentioned seeing them around. This is just four or five years ago!