S & W probably make the best double action triggers both in the revolver and autos. Tell your friend if he can't find a good Double action only gun to buy a double/single action like a Beretta M9. Eact time he fires he can simply decock the hammer and use the double action mode. This is also a good drill for holster draw practice. Draw, shoot, decock, reholster. The U.S. Army teached a double tap thing that involves draw, fire, fire, decock, reholster. Finally, a good double action revolver is excellent practice for shooting double action. Ruger is now making thier GP 100 (I think) with a 108mm barrel, handled one Saturday, quite nice and sure seems like a 4" gun.
Scott