I actually JUST got a
GLOCK 31c. I'm pretty sure it is a supported chamber. Have a look
That IS supported right?
To the OP: I've spent the last 2 months doing all the research I could, to find out about the 357sig. I have a bunch of good links, mostly dealing with reloading...since factory ammo will make you cry. Availability and price are a HUGE issue for me.
I got a 40s&w barrel as well, so I can shoot .40 with just a simple barrel swap.
About halfway down this page theres a list of all the firearms chambered for 357sig, you can find most of them in Canada. --->
http://www.handguninfo.com/Archive/www.Pete-357.com/
Take a peek at the ballistics data for 357sig and compare it to whatever you were shooting before, 9mm,.40,45...You're in for a treat