Security Six vs GP100?
1)Yes, I have some Security-Sixes and two GP100's!
2)The GP100 is an updated revolver that is based upon the original Security-Six design. However, it is built on a larger frame the size of an S&W L-frame(The Security-Six is approximately the same medium frame size as the S&W k-frames).
3)Although the larger frame of the GP100 is stronger(And because of the front S&W triple lock type, cylinder lock-up!)than the Security Six, both of these revolvers are super strong and are as tough as nails! There were no weaknesses in the Security Six that had necessitated, going to the larger GP100 frame(As was the case with the weaker S&W K-frame-which wasn't nearly as strong as the Ruger Security-Six and therefore needed to be upgraded to the larger(Stronger)L-frame!)as the Security Six was designed to fire the .357 magnum rounds regularly, from day one! Whatever difference in strength(Although better!)that the GP100 has over the Security Six wasn't really needed(Since the Security Six has a long(Proven)history of being a super stong, medium framed revolver(The same is true for all off the "Six series" Ruger revolvers(Security/Service?Speed Sixes!)!
4)Both the Security Six and the GP100 are quality built revolvers! However, I believe that the overall quality of the Security Six is better than the GP100(Afterall, this was Bill Ruger's first double action revolver-and, for him to have succeeded in the market(Against the traditional Colt & S&W revolvers, mean't that he had to put his best effort into building a great revolver-or else, would have failed in this market!)! I also like the strength of the Security Six(For it's lighter, medium weight frame size!)as well as is greater ease in handling! And lastly(Just my humble opinion!)I like the looks of the Security Sixes better than the GP100's(But, I do like both of these revolvers!)! There have been recent reports that Ruger quality control had slipped, since the passing of Bill Ruger !