I have that same rear sight on my Springfield.45...for the last 12 years.
I never holstered it as it is set up for just target shooting and it does hang over the back of the slide a bit.
That sight was marketed by various companies through the years and I think even used on Sigs .22 target pistols.
Mine was sold as a Pachmayr, even the screwdriver is so marked.
It came in all black, 2 white dots or the white outline, which I have.
I let a 'smith knock out the original sight and install the new one, it was really stuck, laughing at my best attempts with a plastic, then brass drift and a bigger hammer.
Same problem here, $50 for a one time sight changeover or big money for the universal tool was out of the question.
My 92 shot the bullseye at 6 o'clock at 25-30 feet so the tallest blade of the 3 included with the Beretta sight assembly was used to bring it to center, dead center.