My father left me a unusual Iron sight and base and am interested in knowing something about it. I believe it is a 4 leaf express with tangent. The base is 3/4" dia. that is mounted around the barrel and is 3-1/4" long with the barrel bore being approx.13/16" probable secured with silver soldered on and has and the sight dovetail 2-1/2 long. Thanks in advance. Geo.