Due to the larger capacity of now six instead of five cartridges, the diameter of the cylinder also grows. The next size, the K-frame, is considerably larger than the small J-frame. In addition, the cylinder stop on the left side of the frame is a rib, while on the old model it is a round boss. On the new model, the firing pin sits in the frame. Of course, one always identifies an L-frame revolver by the massive barrel with muzzle-length ejector housing.įor example, if you want to use the oversized Nill wood grip in the Phil Hemphill design in PPC shooting sports, you must first determine if your existing revolver has the old or new J-fame. 357 Magnum, the dimensional differences are already harder to see. In the case of a S&W M19 with K-frame (below) and a S&W M586 with L-frame (above) in. Some were even made with a square grip, otherwise this revolver frame ran and still runs off the line with a "Round Butt" grip. A look at the table reveals that the top strap width of the J-frame is the smallest at 13.6 mm. The original I-frame evolved first into an Improved I-frame with the release of the Model 34, and later into the J-frame of the typical S&W pocket revolvers that is still available today. We measured all six frame sizes currently available and show the differences in the table below. The counterpart to this would be the square grip shape called Square Butt (SB), where in the side view the grip frame appears bell-shaped. If the grip frame is rounded and shorter, this is called a Round Butt (RB). In addition, there are two grip styles for the popular frame sizes. 45 Colt/.410 bore is much smaller than the mighty, steel X-frame of the 500 and 460 models chambered in the. That's because the scandium alloy Z-frame of the Governor model in. But unfortunately, no rule is without exception. The further the letter in the alphabet, the larger the frame. Currently, frames with the letters J, K, L, N, X and Z are still being manufactured. S&W revolvers with these frames can now only be found on the collector's and used guns markets. Historically, as many as eleven different S&W frames exist, but the Top Hinge, Top Break, and M- and I-frames have been phased out, while the C-frame did not make it past prototype status for only the Model 73. To the naked eye, the differences can be seen on the forcing cone area and the barrel. A S&W M60 with J-frame (below) and a S&W M66 with K-frame (above) in.