So here's what I'm working on:
![img](http://i127.photobucket.com/albums/p142/gunboat57/Krag/1902withM96_zpsb9855d3c.jpg)
That's a Williams rear sight made to be installed in place of the sight leaf of the M96 Swedish Mauser. In the 1902 base it fits with only about .010" of side to side looseness which could be shimmed. The windage adjustment "ears" of the Williams sight stick out a bit too far for me to lower the sight more than the picture shows. But if needed I could trim those ears a bit in order to lower the sight.
Bottom line is it's a barrel-mounted aperture sight that requires no permanent modification to the 1902 sight. And I know it will work for me because I used to have it mounted on my Swede and was able to shoot consistantly with no problems.