I bought an 1886 Winchester (Japan) in 45-70. The PO had installed a Lyman tang sight.
In all my years of shooting this is my first experience with this type of sight.
The rifle is amazingly accurate. But once sighted in, the sight itself wobbles quite a bit and at over 100 yards it is effecting the windage POI. The elevation stays spot on. There does not appear to be anyway to "lock" the sight once it is set.
The wobble comes from two places.....minor wobble where the sight sits in the piece that is attached to the tang, and major wobble where the sight elevates on the threaded shaft.