In my opinion it is the best revolver ever offered by Ruger. I'll start a brief history on the Security Six .357 Magnum. It was introduced in 1968, released in 1971, and in production between 1972-1988. I know that sounds confusing, well it is. That's because there were two major "frame types" released. The early model 150 prefix and below had a "square" butt with a duck's tail on the end of the frame; the idea was to control muzzle flip. The 4" blued model pictured above is a very early 150 prefix model, made in Jan, 19 1972. The end result was that the "duck's tail" stabbed hands upon recoil and it continues to stab my hand when shooting very heavy loads, but not as much as you would think. It takes me about 70 heavy loads before I start to get annoyed. In 1975 they brought out the stainless model. And in short order Ruger followed it with a giant warning message right on the barrel. Early examples without the warning may be worth more to a collector. My stainless 4" above wearing the Kindwood grips is a 151 prefix without the duck's tail but with this warning.
A rare model is the Stainless 2 3/4" Security Six without the warning message, also pictured above. It took me forever to find one in this condition, see not a scratch:
Many more of the shorter barrel models were made of the Speed six and Service Six variants, buts that another review. In 1988 Ruger broke my heart and discontinued the Sixes. The GP100 is a great gun and many people do not understand the differences between them and the Sixes; well, the differences between the Security Six and the GP100, are as follows: First, the Security Six has a full size grip frame compared to the GP100's "stub" grip frame. Also, the GP100 has a locking piece between the yoke and frame (instead of between the ejector rod and barrel) and a fixed (non-rotating) ejector rod. The reason for the change is more theoretical than real with the main advantage of the GP100 being the front lock-up being right at the front of the cylinder, instead of out on the end of the ejector rod, but that is a slight advantage. The real motivation was that the GP100 is less expensive to produce than the Sixes were. Furthermore, the full under-lug on the GP100 is there to reduce muzzle flip, some like it, others don't; I personally prefer the look of the half-lug for aesthetic reasons only. Other than that most differences are cosmetic, such as the barrel profile.
And this is why my beloved Security Six is no longer made....
As for the accuracy of this fine weapon. I do not believe in firing from a bench rest to test a handgun. It should be tested as it should be used. Here is three 6 round groups at 14 yards with the 2 3/4" Security Six using my favorite load: 158 grain Hornady XTP: