I have had zero problems with the Storm Lake 9mm barrel. I've read several reports that the Storm Lake barrel is actually more accurate than the factory barrel. I don't know if that's true or not. I get excellent accuracy from both the factory .40 S&W barrel, as well as from the aftermarket Storm Lake 9mm barrel. Generally speaking, 9mm ammo will be more readily available, and cheaper than .40 S&W. .357 Sig ammo is pretty hit and miss with regards to availability, and the price is pretty high. I noticed you mentioned this will be your first handgun. If you are looking to maximize your experience, and minimize your costs, I would strongly suggest buying a .22 caliber handgun to start with. You should look at either a modern, double action revolver, or a semi-auto pistol. S&W and Ruger make excellent quality, and affordable .22 caliber semi-autos that would be excellent training guns. .22 caliber ammo is cheap and plentiful. You can build good habits with the .22 before moving on to more powerful center fire calibers. Bad habits are hard to break, but easy to develop. If you have your heart set on a center fire caliber, I'd consider a used .38 Special revolver to start with - especially one with a 4.0 inch barrel. They are inherently accurate, and easy to learn on. .38 Special ammo is easy to come by, and should be affordable - more so than .40 S&W ammo. The .38 Special revolver is very versatile and can be used for informal target shooting, self/home defense, and small game hunting. It is my favorite caliber and I own more .38 Special / .357 Magnum revolvers than any other revolver or semi-auto in my collection.

Best of luck,

Dave