Quoted By:
Here is a Colt Trooper Mk. III, a double-action/single-action hand-ejector revolver, in .357 Magnum
This one is built for a laser sight setup that was absolute top of the line for the time period, customized to accommodate it as best as it can. In the year 1980, this was probably the most compact laser sighting setup available.
The grip is shortened down, and the battery pack for the laser is fitted under there as an extension (noticeably, slightly longer than the normal grip), the laser unit sits on top, with backup iron sights on it, notice the hammer which has its spur widened to allow you a better grip purchase from the sides, as the laser is in the way from above.
I don't remember much of the specifics of their specs, but these kinds of old lasers actually used gasses like helium and neon, and generally required something 10,000 volt to light up. Most laser sights these days are done differently, using a much more compact and energy efficient setup with a diode.