Well, guess what? It worked!
BEFORE: Standard XD sights

AFTER: Advanced Tactical Sights

With the right tools and some good advice from folks here, I was able to remove the XD sight and install the new one.
Here's the setup I used after purchasing a couple more stuff from City Mill. The sight tool is clamped on a vise clamp. It would not have been possible to do this without the vise clamp and a wrench.

I applied Liquid Wrench Penetrating Oil on the front and rear sights a few hours before attempting to work on it. Then I just let it sit for a few hours.
First step was to remove the rear sight and I had to use the sight tool and a wrench to remove it. The slide was flush on the shim that came with the sight tool so it was easy to align it up in the tool. I added a dab of liquid wrench on the rear sight before pushing it with the sight tool.


Once the standard rear sight was off, the AT rear sight was really easy to install and only needed the tool that came with it to tighten it to the slide. I did not have to use the sight tool to install it.

The front sight was a bit harder to align on the sight tool as the slide would not it with any of the tool bottom shims installed. I had to remove the bottom shim for the slide to fit. I ended up scratching up the bluing while trying to test the fit.

I decided to use masking tape to protect the slide finish and it worked well. It was better than trying to hold a piece of paper towel or patch against the slide while tightening the tool.

The front of the slide was harder to line up in the tool as the tool was looser than a Glock. Taking off the front sight took more time because it was hard to make sure everything was perfectly aligned while tightening the tool.

Aligning everything to install the front sight took even longer and I had to manipulate the slide and tool several times to endure they were lined up well. Once it was lined up well, it was easy to get the front sight pushed using the tool.

One thing about the AT front sight, I can imagine it would be quite challenging to sight this in because one would have to take the front sight out to add shims into the front sight. To do so, you would have to unscrew under the front sight to remove the top component of the sight, insert the plastic shim with the appropriate thickness, then put everything back together again. The thicker the plastic shim, the lower the point of impact on the target.

For the scratches, I was recommended a Brownells Dicropan T-4 Touch Up from a guy at Security Equipment to fix the bluing. I'll have to do a separate review of this once I finish sighting in the new AT sights.
