It looks very like Mauser, rather than Krag. I've also never seen one bent like that so I'd guess it has been bent after leaving the factory. Front-hinged, so it has the "roller coaster" type assembly on the top of the barrel that the elevation slider adjusts on. Initial guess is 1893 or newer; the 1891 had the hinge pin at the other end. I can take a look tonight to see which of my Mausers' sights this matches, but it's 1893 or later.
Dave Hinz