I had posted last year about my M&P 40 shooting very low. I had let a couple of friends try it as well and it wasn't the shooter, it was the gun. I called S&W customer service and while they were very helpful, they weren't able to resolve the issue. They said that I needed a new, lower front sight .210'' in height and they would send one one out to me. A couple of weeks went by and I hadn't heard anything so I called them back and I was informed that they no longer carried the lower front sight. I poked around on the internet and I found a Ameriglo tritium front sight at the .210'' height. I ordered it and it came promptly, but it didn't glow. I had to send it back for an exchange and about a week ago I finally got the replacement sight and it worked like it should. I replaced it and took it to the range, and it fixed the problem. I'm finally very happy with my M&P. After some more range visits, it will be in my concealed carry rotation.