A 3" K frame with a round butt grip is just about the ideal walking around revolver.  Mine is steel and gets a bit heavy by the end of the day but I like it all the same.  I think the last aluminum K frame they made like that was the old model 12 and they haven't made those in years. 

Agreed.  My own experience with aluminum framed revolvers is primarily with the Colt Agent from the 1980's.  Nice little revolver and I have considered bobbing the hammer but am loathe to start cutting on discontinued things with the rampant colt logo on them.  I do have the hammer bobbed and polished on my model 13 and although it is larger and heavier than is common for concealment guns it is pretty unobtrusive and handles well.  I think the weight helps when keeping the sights on target for a full cylinder of defensive ammo.  A set of Craig Spegel boot grips also helps some. 

I seem to recall that S&W had some reliability problems with the aluminum frames on the model 12's early on.  I think the ancient side plate design of the frame created some problems not encountered with steel frames.  Might be a complete non-issue with some of the more exotic alloys available to them these days.      I recall the model 640 being offered with a 3" barrel but apparently it was discontinued as I almost never see them anymore.  A friend had one of the Custom Shop "Scandium" revolvers - a J frame with a three inch barrel and it was light enough to be blown off the shooting table on a windy day.  Ok - maybe not that light - but it was a vicious little beast with .38 special +P ammo and .357 magnum loads.   A K frame in aluminum would weigh a little more and spread out the force of the recoil over a larger grip area and thus be much more comfortable to shoot.  IMO.   

I've been saying that Ruger should scale up their LCR to K-frame size. One version chambered in .38 Special, possibly .357 Mag, and another chambered in .44 Special

44 special is a tragically underrated cartridge. It is just great in shorter barreled revolvers.

44 special is a tragically underrated cartridge. It is just great in shorter barreled revolvers.

Agreed.  I have been eyeing the GP 100 in that caliber since it hit the shelves.  That gun is what I had hoped the old Charter Arms Bulldogs would be but never were.  A friend with a New Model Blackhawk in .45 Colt has been loading it with heavy bullets and a case full of Trail Boss powder and that thing is the most fun you can have with a pair of chaps on.      We were discussing the .44 Special in that context and are both of the opinion that a 260 grain bullet in that caliber with a case full of Trail Boss behind it might be the best all around, big bore six gun round there is. 

I have gotten over my infatuation with the 10mm as a revolver cartridge since it seems overly finicky about moon clips and the bullet selection is in no way as diverse as the .44's and .45's .   Might change my mind if somebody comes up with a 10mm Auto Rim that works in the Ruger revolvers but I'm not holding my breath waiting for that to happen.   

I was wondering about that.  Might work but the rims seem too big around and still not thick enough to function like the old .45 Auto Rim does.     I'd also have to come up with some kind of speed loader unless I just used re-purposed Speed Strips or belt loops.  That would kind of take the shine off of owning one of those spiffy new Ruger 10mm revolvers - IMO.