+1 on this as well! Love the versatility of the .40 S&W M&P! Now if someone would make a 9mm conversion barrel for the 40 caliber Shield that would be great!if you go back just a few posts, you'll see your question asked a number of times.
the answer is NO, unless you buy a complete 40 slide/barrel assembly and mags.
that's why a lot of us buy the 40, since you can shoot 3 different calibers, for very little investment.