I keep hearing that the heaviest bullet in a given caliber is the right move, because penetration is 'better' than expansion. So why has the .357 mag reigned for so many years, and why does the .357 Sig follow the 125 gr tradition? Is it because, for most of the 357's reign, it had hardball 9mm and .45, and RNL .38 special as its competition...? But if that's true, why a 125 gr .357 Sig? Why not a 158 gr bullet? Too long for the case?