I've got a couple, chopped from their original barrel length and in both cases to a little over 3".
First is a 624 (not a usual candidate for this sort of thing) that was a 4" but must have suffered some muzzle damage. The barrel and ramp were both shortened to 3-3/8". It was also round butted to accept these K-frame Pachmayr grips.
Second and most recently is this cut down and hard chromed 1917 (shipped April of 1918). It's barrel is about 3-1/4".
Although I generally prefer 5" N-frames these two, since they are in my two favorite calibers, are instant favorites.
Dave