Gentlemen, I have come to a dilemma; I'm currently deciding between a Ruger GP100 in either 4 inch, or 6 inch barrel length. I am trying to determine the minimum barrel length required to get the full potential from the .357 Magnum cartridge. What would your recommendations be? This would be a range toy/SHTF Zombie killin' gun , so I am just wanting to get all I can out of what I buy. Is the difference between barrel lengths going to affect the muzzle energy and velocity to the point where it becomes a selling point for me? I.E., if the velocity and muzzle energy are only affected by 50-100 FPS or FT/LBS, then I see myself going for the 4-inch barrel, but if its a significant difference, the 6-inch is the way to go, I suppose. What other factors must I consider when deciding barrel length, when it comes to also keeping the caliber in mind?