For those thinking a 357 sig is the same as a 357 mag. They are not the same. The 357 sig is a souped up 9mm bullet. Nothing more, nothing less. As far as the 357 sig having the same stopping characteristics as the 357 mag. They do not.
The standard 9mm WOULD ALREADY out penetrate the 357 mag, and would do so 20 years ago. It is about bullet design, and configuration, and the 9mm will never duplicate the 357 mag regardless of ballistics ON PAPER.
The 357 mag, was what it was, and is what it is, is because of the bullet design, i.e. configuration. It is broad across the nose, and delivers better energy on impact than the 9mm 357 sig. It is not totally reliant on expansion, and give a good balance of penetration, and energy delivery to the target. Something the 9mm has never done, and never will, as it is totally reliant on expansion, once again due to bullet design, i.e. configuration, and for those other folks, SHAPE. It is what it is.
If Glock or any other firearm manufacturer were interested, it would be very easy to duplicate the REAL 357 MAG, by simply producing a 357 mag case RIMLESS, enabling an ACTUAL 38 caliber bullet to be used in the proper bullet configuration. Then, and only then, would one have a REAL 357 mag auto, and it would be in the same arena as "the original 1 shot stop king".
Believing the 9mm 357 sig can perform like the original 357 mag 125 grain JHP in a fight, is much like putting a collar on a coyote and calling him Spot. He will still steal your chickens.
BTW. After experiencing some of this reality on the street, and training many an officer how to survive a fight. I carry a 40s&w. AND! Before anyone takes offense to my remarks, I will say for 20 years it was my job to know these FACTS, and you are not required to accept, or agree, with anything I have typed here.