Guy's I'm seeing a lot of talk about interchanging barrels. If I buy the M&P in a .40 or 9MM, I can buy a factory barrel for the 357 sig and use it in the same frame?
With the M&P40 or 357 sig you can interchange barrels and mags. You can also get a 9mm barrel and mag and shoot that round. You cannot go from the M&P9 up to the 40/357 as the breech face does not match up.