OutWest50 is mostly correct. All K and N frames did originate with right hand threads until changed to LHT in an ~ 1959-60 transition period. Of course all new models introduced since then have LHT.

However, I frames have a different evolutionary history; they also did originate with right hand threads. However they transitioned to LHT when reintroduced in the immediate years following the end of WWII.

The J frame originated with left hand threads in 1950.

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Jim
S&WCA #819