There are so many issues for your quest.
S&W will not sell you a frame, a barrel or a cylinder, the S&W Warranty center might get you a cylinder, but your problems are only beginning. S&W 686 cylinders do not offer enough material to convert to 9mm, fitting it could mean changing the dimensions of the force cone.....etc.
Why not just buy the S&W purpose-built 9mm revolver?



























