Wow, just got back from the range. I shot 150 rounds through my new model 31. I was the guy that had the rusty M&P. I will say the 357 sig has a lot more recoil than the 40 s&w, and is a lot louder also. The first round turned everyones head. Than after shooting that I shot 100 through the M&P and the 40 felt like a 9mm. I am going to buy a 40 barrel for my 31, but for self-denfense I won't carry anything but a 357 sig now.