I just purchased my new XD-9, a real sharp looking 4" bi-tone 9mm service model and let the gun shop install a set of William's Fire Sights... The gun shop trashed the front of my new XD-9 so bad, they had to send it back to springfield for repair! It looked like they used a railroad spike and a sledge to remove the factory sights and install the new ones!

The front sight was in such bad shape, it wiggled around when you moved the gun, and then broke off on one side while I was just looking at the sights! If you value your XD, keep this story in mind, and be extra careful with who you trust to install your sights. Springfield admits that the sights on the XD's can be tough to change out... I hope when I get my XD back from the factory, it looks O.K.!
