There's a ton of good advice on this thread from people with much more revolver experience than I, but, FWIW, here are a couple thoughts.
I have a pair of 642's I bought new about a year ago. They were my first handguns after a lifetime of long gun shooting. Both shoot basically identically, and I have found that 158 grain, standard pressure loads shoot basically point of aim out to beyond where I can clearly see the target. If other 642s are like mine, the gun is totally capable of consistent, accurate 25 yard shots.
Second, both have nice smooth, predictable triggers with a very slight "notch" right before the hammer drops. With this, I can stage the trigger for long, slow shots and it's basically like single action. You're not being timed, so this method could work for you.
Finally, my eyes are the limit at that distance, not my gun or even my ability to hold my sight picture through the trigger press. I'm nearsighted, but with my glasses on I have a hard time seeing the sights. It's not a problem outdoors in daylight, but my local indoor range has poor lighting at the far end and it makes it really hard for me. Hopefully you have better eyes, or a better lit range than I do.
I love shooting my little j frames. A lot of people complain about how they hurt and all, but I just don't get it. I shoot with them every chance I can get, and like the challenge of getting really good with them. It's funny, my wife got an M&P 380 autoloader not long ago. We took it to the range and I ran a few magazines through it. Having shot no handgun other than my J Frames over the past year, that thing felt like shooting a rifle it was so smooth and easy, and so easy to keep on target. It is, however, way too big for me to daily carry, and I love the simplicity and reliability of a revolver, so I'll keep on carrying and shooting my Js. Getting really good with a J will make you a better shot with any gun, for sure, but they're very good guns in their own right. I suppose it's why they've been around for over 70 years now, basically unchanged.