Three caliber kits ...

[rwbeeman]

I would like to see S&W make and sell SA pistol kits that would
include .40 cal, .357 Sig, and 9mm. This would provide a versatile weapon. Nine MM for defense and practice, .357 for serious defensive use and .40 cal to remind yourself why you
don't shoot it often. All three barrels and the 9mm and.40 magazine in a nice foam lined case.

 

[Frank237]

SIG 320! ALL you want.

 

[wadcutter1]

I have no personal experience with it, but I believe you can get a Storm Lake barrels in 9mm and 357 sig for a M&P 40.

I shoot 9mm in my Glock 22 all the time.