It gets better - buy a .357 SIG barrel (.357 SIG = .38 bullet in a necked-down .40 case) and get a third gun, flatter shooting with higher muzzle velocity (but less down-range energy). With the .357 SIG, you can use any of your glock .40 magazines. If you get the 9mm barrel, you will need to use 9mm magazines. Still, pretty cheap way to get three guns in one!
During the great ammo shortage last year I couldnt find much of any handgun ammo other than some 38 special and 9mm, so I decided to stay with the nine.
Load the Glock 19 or 26 with Golden Saber or Corbon Powr Ball ammo and you have guns that are just as peppy as a 357 magnum with ammo a lot easier to find.