Got myself a M&P 40, with the plan being to use it as a multiple caliber gun. Here's my question, getting a 9mm barrel for it is almost a no brainer due to the cheapness of the ammo, and making it an option in times of limited availability, but what about a 357 sig barrel? I can't think of any benefits over a .40 for competition or target practice, but what about for hunting and self defense? I can honestly say I have a bit of an infatuation with this caliber, and just wanted to see what others opinions of it were before I spend money. A new barrel can be had for about $70, and of course the ammo isn't cheap, but I would be able to plink, shoot matches and such with .40 or 9.