M&P - .40 in a 9mm?

[M&P 40]

Good info on the .40 to 9mm. Is it possible to go from 9mm to .40 with
the M+P if you could purchase the right/different barrel?

Can't go 9mm to .40 without changing the slide,the 9mm and .40 have the same frame though. There are conversion barrels from .40 to 9mm that are sold by Storm Lake and you can get them from Questar (a sponsor at the top of the page)