I have a square butt model 19-2 made in 1967. When I bought this gun it had rubber grips on it and I shot it that way for a few years. I then decided I wanted to put on some combat grips on it and I removed the rubber grips to find a square butt. So I am guessing someone changed a 4" barreled gun into the 2.5" gun and probably added the gold wide target trigger and hammer at the same time. I like the target hammer and trigger just not so much the gold. I also like the looks and feel of it of the square butt.

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