I just recently purchased a S&W MP Shield. I found it very hard, if not almost impossible, for me to rack the slide back hard or even operate the slide stop. I was told that I should shoot it and brake it in and it would get easier to work the slide. Well, as there isn't anyplace near me that I would go to shoot it except the Bull's Eye indoor range in Tacoma to do that (I don't like the Clear Creek Range nor the Gig Harbor ranges) I decided to brake it in using the "Handi-Racker" This worked good and I worked the slide back and forth and dry fired it each time for over 350 times. The slide didn't really get any easier for me to work. So, I purchased a Stainless Steel Guide rod with spring. It got to me today and I installed it. What a difference it made. No problems now. However, I also noted that +P ammo isn't recommended (and I just purchased two 50 round boxes of Federal Premium Law Enforcement 9mm Luger +P 124 Grain HST) Guess, what I will do is go to the range and install the old spring and shoot the 100 rds. I can understand the reasoning for not using the +P with the new spring as it is so much lighter of a spring it would probably slam the slide back to hard into the frame of the pistol and cause damage. Made my want to ask the question: Has anyone that has installed this spring into their Shields experienced any problems with it?