The shape/contour of the cam protrusion is different than that found on S&W pieces. Similarly, the surface finish appears much rougher than that produced by S&W---although a combination of wear and the significant magnification provided by the photos could be the culprit here. Finally, we're shown both sides of this piece, and neither shows the slot for what I'll call the sliding bar and spring to be found on S&W's (with this type of mechanism).

Bottom Line: I don't know what it's for, but I know what it isn't for.

Ralph Tremaine