I have a SS4" 66-1 .357 with CTC grips and LOVE IT. It is as strong as ANYOTHER medium frame revolver in the industry. And yes, the Rugers are cast but Ruger is one of the premier lost foam casting companies in the world. I wouldn't hesitate to own a GP100. They are GREAT guns. (But yes, they are not AWESOMELY advanced over the tried and true S&W!)

Either gun is a fine piece,
RA