I recently purchased the M&P 45 and also own the M&P .40; they are identical looking, even the clips. I was at the range and loaded the 45 and .40 clips. Just before I was ready to load the 45 and shoot I started talking to someone for a minute and got distracted. After I was done I grabbed a clip and shoved it into the 45, and racked a round into the chamber. I put a bead on the target and pulled the trigger. I felt no recoil and just heard a thud!. I realized right away that something was wrong, so I popped the clip out and realized that I had loaded the .40 clip in the 45. I removed the round from the chamber and the brass pretty much had come apart. I disassembled the 45 and inspected everything and it looked ok. I'm now going to mark my clips in such a way that this won't happen again. Just wanted to share my experience with everyone else.