Well that was easy! I used the Maryland Gun Works tool and it was a 5 minute job. Only mistake was using tape to protect the sides of the rear sight. When I removed the tape most of the Trijicon identification data came off with it! Lesson learned? Use tape on one side of the rear sight - the side without the identification information - and use the tool to push on that side.
You dont need the tool, it took me same amount of time to swap sights on my 23 using just masking tape a small hammer and a drift punch on top of a rubber block. Took me longer to get that tiny ass screw on the front sight started than anything else..
Good deal. I'm thinking about putting a set on mine and am glad to hear the installation is pretty simple.
I should add a qualifier: It may have been because of the Nickel Boron coating on the slide but that HD Night Sight was a very tight fit in the dovetail. I had to really crank down on the handle (one hand only) of the installation fixture. It was a 5 minute installation but the amount of force required surprised me. In fact I almost stopped and took it to a gunsmith. If I had used a punch I'm afraid I'd have screwed up the slide and sight or just given up. I've never installed sights so perhaps it's always a tight fit.
A good gunsmith would evaluate the fit before installing the rear sight but it looked so simple... Like I said - it was tight and I don't see that sight ever moving if I were to drop the gun, or throw the gun against a concrete surface, or run over the gun with a tank! I probably could use a punch to make a small adjustment but in my case, with this particular G20, with the slide coating, and with this Trijicon HD Night Sight, a lot of force was required to get that sight to slide-in and I was glad I used the fixture.
In comparison the standard Glock plastic rear sight slipped out with the fixture as if it were in soft butter.
I should have added to my original post that i would recommend a softer punch like brass rod or delrin to help avoid damage to the finish. I just used one of my larger steel punches with a couple of layers of masking tape.