All 3rd gen Smiths have a steel slide. The 3913 has an alloy frame. The 5906 has a steel frame and is considerably heavier as a result. The 5904 is the same as a 5906 but has an alloy frame, (and black finish). I prefer a 5904 to a 5906 as a result of the lighter weight. The 3913, though a "bright" finish, also has an alloy frame. I have one 5904, two 3913's, and one 908 (same as a 3913, single stack, alloy frame, but black and in the "American Value" series). I think the 3913/908 and the 5904 are great carry guns, a 5906 not so much because of the extra weight. They're all as reliable as the sunrise, and I personally like the S&W 3rd gen's "92 style" decocker/safety.
