P226 .40s&w and .357sig
I have had a P226 sig for about 4 years now I purchased it from CDNN it was only available at the time in 9mm and .357sig. I got the .357sig, and purchased a sig barrel in .40s&w for around $169, just like having 2 guns. I prefer the .40 to the .357 mainly on cost of the ammo. However when it is time to show off I love the .357sig... 12 rounds 1.5" group @ 15 yards vs 3" group with the .40. I have shot at least 3000 rounds of the .40 and 500 of the .357 through this pistol without a single malfunction of any type, ever! I would recommend that you buy one with the tritium night sights, buy it asap.
Only difference is the barrel, magazines are the same, recoil spring is the same. Different story for the Sig P239 compact magazines are not the same, however you can use .357sig in the .40 magazine but not the .40 in the .357 mag.