Chris, I have a Ruger Super Redhawk in 454 Casull already and the 500Mag is a good step up from the 454 Casull. With the problems they are having with the 460 S&W, I don't think it will be out soon and I really do not want to have problems later down the road if I got one.
Also I did not see the real advantage over the 454 Casull. And if I really wanted something big the 500 Mag would fit the bill.
