I had a customer send me a picture to see if I could repair his Springfield Armory XD slide. He had taken his pistol to a professional gunsmith. The smith had assured the customer he could install his new sights. After a couple of days, the customer returned back to the shop to pick up his pistol. This is what the customer walked into. The factory sight was not removed and the slide was damaged. From my experience, it looks like the smith tried to us a large punch or maybe even an air chisel. Using the wrong tools resulted in the punch or chisel hitting the actual slide and denting the solid steel of the slide.

Even after the first the damage occurred the smith continued pounding away at the sights and slide. As an experienced gunsmith, I have been in situations where the firearms does not want to cooperate. You may have a pin or a screw that just does not want to come out. I will admit in my younger days I was guilty of going to get a "bigger hammer" and the result was always the same. I would get frustrated and mess up the firearm. About the best piece of advice I could give when it comes to gunsmithing is if you start to get frustrated and tired and nothing is going right just walk away. The worst thing you can do is go get a "bigger hammer" and force the work while you are compromised. Take a step back and drink some coffee or what ever you do to calm down and reassess the situation. Unfortunately for this customer, fixing the damage will require hours of repair and an expensive bill. 

This is a video online showing someone using a really big hammer to remove his sights. On his thread on XDTALK.com he mentions he was able to get the old sights off and the damage was minimal. I guess it works for some.