Originally Posted by Javelin
Why not just get a G22/G23 if you want to shoot 40S&W....
Or is that too obvious of an answer?
Not at all. Either that or just get a .40 conversion barrel.
I guess the only upswing of knowing you could fire .40 ammo out of a 10mm is as mentioned above by nicke10, if you are in a pinch. Take an extreme example...say I was on a hunting trip up in Alaska and stranded somewhere with no 10mm ammo, and the only thing I could scrounge up was some .40 I found in a cabin, it's good to know I could use the .40 ammo in my Glock 20.