Most L and N frame revolvers with adjustable rear sights (and that's most L and N frame revolvers) have a front sight that's either pinned or dovetailed in place. The dovetailed sights are obviously hammered out sideways with a punch. The pinned sights are trickier. The pin has a domed head, so it must be driven out with a cupped pin punch, and there's some tolerance to the location of the hole, so replacement sights don't come predrilled- they must be installed first, drilled in place
very carefully, and then the pin must be driven through. The pins reportedly bend or break easily if they're not installed with the utmost care. It's technically possible to do this at home with simple hand tools but I've been advised not to try it.
In terms of "acquiring it for a different revolver", most J and K frame Smiths aren't set up for this kind of front sight; the factory sight is usually integral with the barrel. It's possible to cut off the factory sight and refit the barrel for another type of sight, but this requires serious gunsmithing well beyond the skills of most hobbyists.
OTOH if you're talking about the orange-red plastic dot that comes in factory red ramp front sights, it can be repaired with generic casting resin. There's an instructional video on the MidwayUSA website.
