In the early ‘90s, spurred by Texas troopers and rangers who loved the SIG .45 pistol, but missed that “lightning bolt” stopping power effect of their old .357 Magnum revolvers, SIG worked with Federal Cartridge to create the .357 SIG round. It resembles a .40 S&W necked down to 9mm, though the actual construction is somewhat more complicated than that. Different companies load to different velocities, and depending on pistol and barrel, factory 125-grain JHPs are delivering 1,325 to over 1,400 fps.
High-tech bullets that open rapidly, but stay together seem to work best in this caliber. The most widely proven is the Gold Dot. From Texas to Virginia, it has been kicking butt with no horror stories of stopping failures. New Mexico State Troopers fell in love with the .357 SIG a few years ago, and stayed with that cartridge when they ordered their new S&W M&P auto pistols. North Carolina Highway Patrol gave up its beloved Beretta pistols after more than 20 years to adopt the SIG Sauer, because they could get it chambered for .357 SIG.
Gunfights indicate that this cartridge is particularly good for shooting through auto sheet metal and window glass, yet does not deliver on the street the dangerous over-penetration that some gelatin tests had indicated might happen. The spent, expanded bullets are normally recovered from the far side of the criminal’s body, or from his clothing, or from the ground within a few feet behind where he was located when shot.
Winchester Ranger in 125-grain .357 SIG has worked well in actual shootings. Remington Bonded Golden Saber in 125-grain .357 SIG is deliciously accurate, and performs superbly in FBI protocol gelatin testing, though I haven’t run across any actual shootings with it yet. The overwhelming majority of .357 SIG shootings by police have occurred with the 125-grain Speer Gold Dot, and it has worked so well it is unquestionably the most “street proven” load in this caliber.