I had an older first generation M&P with the roll pins and I know that tension keeps them in place. But the new 2.0 have solid pins. What keeps them in place ?
I believe Neal is correct. The 2.0 Compact’s locking block and sear housing pins measure 2.98mm on the ends and 3.14mm in the center. The sear housing pin passes freely through the seat housing assembly and only meets resistance (friction) when installed in the frame. I don’t see any metal to pin contact....SidI assume the answer is "friction". The same for some of the pins in Glocks.