I tried to remove this side plate screw from early non model marked S&W model 12. 1/2 of slotted tip broke off. Luckly other side left and I was able to grab with small vice grip.


I can't conceive of how you could have removed the remnant of that screw with vise-grips.
Well-played.
A clean break like that suggests hydrogen embrittlement. A close look at 20x magnification would tell. That’s a screw manufacturing process error.