The goal of the .357 SIG project was to offer a level of performance equal to the highly effective 125 grains (8.1 g) .357 Magnum load. The .357 SIG accomplishes this with a 125 grains (8.1 g) bullet at a muzzle velociy of 1,450 feet per second (440 m/s) out of a 4 in (102 mm) barrel, which is generally identical to the velocity achieved by standard factory 125 grains (8.1 g)r .357 Magnum loads out of a 4 in (102 mm) revolver barrel.(A check of advertised ballistics both in articles from the late 1990s & current ballistics tables from ammunition manufacturers show commonly a nominal velocity of 1,350fps for the .357 SIG with a 125gr bullet in a 4" bbl.) The .357 SIG gains extra muzzle velocity when fired from a longer barrel, like an after-market drop-in 6 in (152 mm) barrel.(This might achieve a velocity of 1450fps.)
With a simplistic approach to physics, recoil being directly proportional to "muzzle velocity x bullet mass" (due to conservation of momentum), the recoil of the .357 SIG is equal to or slightly less than that of the .40 S&W, and less than that of the full-power 10 mm Auto loads or the original .357 Magnum, Handgun Recoil table as well as Federal and. This simple approach to recoil is only part of the story as it is not only the properties of the bullet that produce recoil, a more important effect is the rocket like blast of propellant gases coming out of the barrel, after the bullet leaves the muzzle, that plays a greater role in the felt recoil. A more accurate view on recoil is that it is proportional to the mass of all ejecta x velocity of ejecta. Even so, recoil calculated in this manner is only the starting point in a comparison with the .357 Magnum cartridge, since the latter is used in a revolver, in which all the recoil energy is due to the Bullet and propellant, while the .357 SIG cartridge is frequently used in a semi-automatic pistol of recoil operation, in which a significant portion of the recoil energy is diverted to cycle the action, effectively prolonging the recoil phase.
In comparing the energy levels of premium self defense ammunition the muzzle energy of 584 ft.lbs (792 J) of the 125 grains (8.1 g) 1,450 feet per second (440 m/s) .357 SIG load is higher than either the 475 ft∑lbf (644 J) generated by a 155 grains (10.0 g) 1,175 feet per second (358 m/s) Speer GoldDot .40 S&W load or the 400 ft∑lbf (540 J) generated by a 180 grains (12 g) 985 feet per second (300 m/s) Speer GoldDot .40 S&W load.
Like the 10 mm Auto, the .357 SIG can be down-loaded to reduce recoil, to the point where recoil is similar to that of a 9x19mm Parabellum. However, since the .357 SIG uses bullets that are generally the same as those used in the 9 mm Para, downloading it to this point would defeat the purpose of having the SIG cartridge in the first place, as recoil and ballistics would be identical to the less-powerful 9 mm cartridge.
Because the .357 SIG fires at relatively high pressures, muzzle flash and noise are significant with standard loads, even with longer barrels. Utilizing loads with specialized powders and experimenting with different bullet weights can reduce flash.