From Massad Ayoob
This is out of The Complete Book of Hanguns 2008.
.357SIG
In the early 90's, spurred by Texas troopers and rangers who loved the SIG SAUER .45ACP pistol, but missed that "lighting bolt" stopping power effect of their old .357 Mag revolvers, SIG SAUER worked with Federal Cartridge to create the .357 SIG round,
It resembles a .40 necked down to 9mm, though the actual construction is somewhat more complicated than that. Different companies load to different velocities, and depending on the pistol and barrel,
factory 125-grain JHP's are delivering 1325 to over 1400 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 autopistols. North Carolina Highway Patrol gave up it's 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 had worked well in actual shootings. Remington Bonded Golden Saber in 125-grain .357 SIG is deliciously accurate, and perfoms superbly in FBI protocol gelatin testing, though I haven't run across any actual shootings with it yet. The overwhelming majority of .357 SIG shooting by police have occured with 125-grain Speer Gold dot, and it has worked so well it is unquestionably the most "street proven" load in this caliber.
From what I dug up, georgia arms sells a great range round that is not too pricey, in Starline cases.
If the swap is as simple as a barrel change, than hell yes, I just might jump on that bandwagon also.
