Thanks for pointing that out. The tool is for the late model screw in firing pin bushing and looks like it would work well. You can buy flat bladed security screw bits that will do the same thing. An internet search will eventually turn up the size needed.

I'm working with an early model SRH which is pinned from the side. The instructions I've seen are to drill out the end of the pin enough so a punch gets some bite and then drive it out. Replace the pin with some drill rod stock or grind it down to shorten it and give you a flat face to drive in with. While those are options, the solutions don't return the firearm to original condition without a lot more work to blend a new pin to match the contour and then refinish the pin and surrounding frame. I've got the target gray model which isn't produced anymore and I'm not sure if Ruger could/would match it and was supposedly a tumble process in a specific media.

A washer or stronger hammer spring sounds much easier.