Another reason why it has not taken hold in the civilian world IMO is because it surpasses the discomfort threshhold for the majority of shooters, as do the hot 135gr. & 155 gr. .40 S&W loads.
The .357 SIG is a fantastic cartridge, but is harder to shoot than 9mm for the average
shooter, as is the .40 S&W for that matter, when solid defense loads are used
. Accuracy & performance mean nothing if the shooter cannot conquer their flinch reflex.
I will go out on a limb and say that if barrier penetration is not
a factor in the equation, e.g., a civilian with a CCW, then I personally believe that any advantage the .357 SIG may have over a street proven
+p or +p+ 9mm is not as great as some believe with proper shot placement
Yes, I own a .357 SIG and love it.