Hi,You mean a M&P. Usually can tell the 1.0 and 2.0 apart is the trigger. S&W is a little weird but has a 4” and a 4.25” model. I’ve got 2 of the M&P’s in 4”
Just measured the S&W 40, and it's a 5", my XD9 is a 4". The XD9 has a RMR plate on it and I think it comes in .40SW