The Redhawk was not just a scaled-up version of the Security Six, for a number of reasons. One important reason was that Bill Ruger was a tinkerer who seemed to enjoy changing his designs simply for the sake of change. Another reason was that he wanted this new popper to be mighty strong.
Ruger certainly accomplished the goal of building a strong revolver, but may have been better served by preserving more of the Security-Six's trigger design, because the Redhawk has one of the worst single action trigger pulls around. Double action pull, as with other Ruger DAs, is heavy and inconsistent.
Like the Security Six, the Redhawk can be disassembled with few tools, one of which is a factory-supplied pin secured between the grips. This is a good thing, but I don't recommend taking your Redhawk apart unless you have 1) a good instruction book sitting in front of you and 2) some mechanical skills.
The Redhawk was designed for the 44 Remington Magnum cartridge, but has also been chambered in 357 S&W Magnum, 41 Remington Magnum, and 45 Colt. For what it's worth, some Redhawks chambered for 45 Colt have shown poor accuracy, presumably due to manufacturing problems.
In the photo above is a Ruger Redhawk in 44 mag, with 5.5" barrel. This version is discontinued, and these days the Redhawk is only offered in stainless steel. Stamped on the left side of the barrel is the obligatory Ruger "read the manual" warning.