Can't see tiny iron sighta any more, so what to do ?
Looking at the 91' and doing some measuring lit the lightbulb !
The real sight has the same width as a common Weaver base.
Dug around in the "never throw anything away" box and came up with a Weaver base with the same contour as the front receiver ring. Some JB Weld put it in place.
A pair of Burris (?) rings to fit Weaver bases completed the mounting setup.
A decent 2-7 IER scope bought on Ebay for 60 bucks went in the rings.
The Leupold bore sighter said a bit of up shimming in the front ring was needed. Had I spent the big bucks and bought the Burris Signature rings with the plastic inserts, the available eccentric inserts could have been used to avoid shimming.
The front scope ring carries the load as it is tightly on the rear sight leaf. The rear one is just to locate the rear ring.
Off to the range with some 4759 cast boolit loads today to see how it works.