A good 6 shot alternative to the 642 for belt carry is the Colt Detective Special, which is all steel and weighs 21 ounces empty. It is easier to shoot well than the 15 ounce 642, gives you one more round, and conceals easily. There are lots of used ones on the market since Colt produced these for many decades.

Here is a picture of mine next to a J frame for size comparison.