The 580/680 guns are the L frames, fixed sight with a 1 at the end and adjustable (like your Combat Magnum) with a 6.

At the small end, there are .357 J frames, smaller than the K; many find these unpleasant to fire with full loads.

For a factory 5" gun, the model 27 (which can be found in nickel) or stainless 627, the J frame model 60, and a limited number of 686s.

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Alan
SWCA LM 2023, SWHF 220