Hello forum, once again I am asking to be educated. I have a model 27, 4 screw made in 1958-1959. that has a red plastic insert in the front ramp sight. Is this original? When did Smith & Wesson first start using red insert sights?

Red Insert front sight is correct for that period. They were first shown in the 1952 Centennial catalog.
Bill

Above is correct. Your gun MAY have come with the red ramp and likely it is original. But not impossible for it to have been added along the way.

I lettered this one because I was curious. The red ramp and white outline letter as original. But the shipping date was later than I thought being 1957.

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Thanks for the answers, helpful as always. Mine has a white outline rear sight as well.