It is pretty rare, according to Nick Strobel's book, it was patented in 1896 and  was  discontinued in 1919.   It is rare, partially because the Lyman 36 came out in 1907.  The 36
was a better sight and didn't involve the removal of much if any wood.  
I imagine that adjusting windage on the Lyman 22 was a real pain, and it was very easy to lose the screw.  Consequently, every now and then you see a rifle with the base
of the Lyman 22 but not the sight stem.   Should you find one in that condition, I've made a couple of stems for a friend and could probably make another.