Thanks for the kind comments, DHart... always very useful suggestions... nearly as nice as your pix! As I stated, the 66's at the pusher's are current stock, complete with MIM parts and a hammer-lock-zit. These are non-issues for me. All of my S&W's, except for an '83 24-3 6.5" and '88 65-3 3", are 2001 or newer. I have had four with the locks, having sold my previous 625-8 4" last spring. I have never taken one of the keys from the poly bag, much less ever tried or experienced any problems with the locks. The MIM parts are more uniform from piece to piece, thus requiring less fitting. They have proven to be at least as durable, but this is an old battle.
I certainly would never fault someone for choosing an older version. In my limited experience, my 24-3 was as near NIB as a twenty year old revolver could be, possessing not even a hint of a cylinder turn line when I bought it. Sadly, it had more QC faults than all of my ten new purchased S&W's have had totalled! If it is an indicator, they certainly don't make them like they once did - and thank goodness!
Back to the K vs L frame.... I have repeated the results of my measuring examples of both frames. The height of the opening is greater, permitting a larger cylinder for my five-shot 296 & 696 .44 Specials and the seven-shot 686+. The topstraps look similar, as are the gripframes, of course. The front strap is some twenty thousandths thicker at the extreme allowing an additional fifteen thousandths extreme diameter for the forcing cone. S&W still rates the K-frames as .357 Magnum capable - and the erosion problem only exists with extremely light and high speed rounds, not normal rounds. The 'little' K-frames, of course, have the same grips - the main difference is weight and it's distribution. The L's are full lugs... except for the 5" h-l 686+ ... where the K's are partially lugged and thus, have less weight 'out front'... the L's stay 'down' under recoil better as a result of their greater forward mass.
I don't know whether I'll make the trek to the pusher today or not... too many sick folks have sneezed at me lately, I seem to be getting a fresh cold. I do think I'll get one of those 66's... my current stable includes a 3" 65 and my hammer-lock-zitted 6" 66-6, and that 5" h-l 686+ (...also sporting a hammer lock!). My 4"-ers are N-frames... and big bores. Choices...
Stainz