In 1994, Sig developed and introduced the 357 Sig. It uses a necked-down, 35-caliber, version of the 40 S&W case with a short neck and sharp shoulder. Working at very high pressure, this results in a bottlenecked pistol round that approximates performance of the 357 Magnum revolver, particularly when loaded with bullets lighter than about 140-grains. Such impressive performance is possible due to elimination of the gas loss that occurs at the barrel-to-cylinder gap in a revolver and the relatively high maximum working pressure, 44,200 psi. In a pistol with a 4-inch barrel, it is no trick to launch 125-grain bullets at 1450 fps. Muzzle blast can well be described as impressive and when such a load is fired in an indoor range it tends to be a bit distracting for other shooters. I prefer to use double hearing protection (foam earplugs and effective earmuffs) when I am around someone shooting such a load (actually, I prefer to not be around someone shooting such loads!). Recoil is noticeably less than typical full-power 40 S&W loads but, due to the 25% higher working pressure, the 357 Sig can generate usefully more muzzle energy. This suggests that given the best modern bullets used in both, the 357 Sig should have a significant edge in fight-stopping ability. Therefore, for those who can tolerate the muzzle blast, the 357 Sig should be a better choice when compared to the 40 S&W. Another factor of no small importance is functionality. While well-made pistols using cylindrical rimless cases have long been proven entirely reliable in the hands of an experienced pistol shooter, it is undeniable that bottlenecked pistol cartridges are more dependable in terms of reliable feeding through the gun under adverse conditions and when the shooter might not be able to engage the gun solidly with both hands. My personal experience suggests that most of the time, as with the 400 Cor-Bon, which used the 45 Automatic case to make a fine 40-caliber pistol round, a bottlenecked round is a better choice for novice pistol shooters. As with any bottlenecked pistol round, best practice is to apply a roll-crimp after seating the bullet. A roll-crimp eases loading of rounds into the cylinder and can help limit bullet pull under recoil if only modestly. I cannot too-strongly recommend getting a second seating-and-crimping die so you can have one adjusted to only seat the bullet and the second adjusted to only crimp the case mouth. Generally, attempting to do both operations in one step is a recipe for damaged and destroyed cases.