I'd say that for the 'No Gunsmithing Install it Yourself Mount." The master mount may have persevered for a few more years. If I had to hazard a guess, I'd say it all came to an end after Redfield acquired Kollmorgen.
"The universal aptitude for ineptitude makes any human accomplishment an incredible miracle." John Stapp - "Stapp's Law" "Klaatu barada nikto"