Most .40 S&W pistols can be converted to .357 SIG by replacing the barrel, and sometimes the recoil spring. Pistols with especially strong recoil springs can accept either cartridge with a barrel change. Magazines will freely interchange between the two cartridges in most pistols, though there are exceptions like the 357 SIG chambered Sig 239. .357 SIG barrel kits have allowed this cartridge to gain in popularity among handgun owners. However, the .357 SIG is loaded to higher pressures than the .40 S&W (a difference of up to 5,000 psi at top loads), and may not be suitable for use in all .40 S&W-chambered pistols.
One disadvantage of the .357 SIG is that it fires a .355" bullet at higher velocities than most bullets of that caliber are designed for. Very few bullets have been designed specifically for the .357 SIG, and .357 Magnum bullets that are designed for the same velocity range cannot be used due to their slightly larger diameter. Because of this, there are fewer ammunition choices in .357 SIG than one might expect for a cartridge using .355" bullets.
Another drawback of the .357 SIG is its often harsh treatment of the pistols that are chambered for it. Many are designed to fire the .40 S&W and are later modified for use with the .357 SIG. Firing regularly at pressure levels effectively beyond what the pistol was originally engineered for tends to translate to accelerated wear on the firearm.