I installed a Burris FastFire 2 on on of my pistols....Made a Picatinny rail to mount on the top starp.
No alterations to the gun I used the two M4 tapped holes. Was concerned with the action but it's shoots the same hole every time.
Backyard squirrels will hate me more.

http://img839.imageshack.us/img839/7250/c5reddot.jpg