But not much else. S&W came up with the L frame when they discovered that the K frame magnums couldn't survive under a steady (read police practice) diet of full powered magnum rounds. They looked around at the 357's that were their main competition (ie: Colt) and decided that a stretched K frame that would fit a larger cylinder was just the ticket. And, as one of the common beefs at the time was the lack of an full length underlug under the barrel (think Python). They decided to add that too. Worked out well. - dan