I purchased a S&W 9mm Shield because of the $75 rebate. I wanted to upgrade my concealed carry gun from the Kel Tec P32 that I have carried since their beginning. I was going for a .380, but decided the 9mm would have a lot more punch. After going over the gun and the Safety and Instruction Manual, I can't for the life of me, determine why there is a Slide Stop Notch in the slide. It doesn't align with anything, it doesn't engage anything, and it appears to have no bearing on the Slide Stop whatsoever. What am I missing?