I had a Burris FF 3 mounted on the slide of my Shadow but it did not survive the recoil. It lasted about 1000 rounds and then started shutting off. Finally would not power back on. Burris has replaced the FF 3 under warranty but it will go on my Ruger Mark III. I would suggest to purchase the best Red Dot sight that you can afford if you plan to mount it on the slide. For me, shooting paper, speed to get on target is not a factor in my choice of dot size. I prefer a small 2 MOA dot with many settings for brightness. I also have a Vortex Sparc 2 with 2 MOA dot but brightness is a little too high on low setting. I plan to mount the Vortex on my GP100 with a Weigand mount. Time will tell how it holds up. Vortex is coming with two new Red Dot sights in the $350 range and I may try the Venom next.