I had TK Custom rechamber three for me into .38 Super/9mm...they run well. 3" 66-2, 3" 60-10 and a 649-1. Found extra cylinders for each rather than modify the originals. The modified ones will still run the original .38 Special and or .357 Magnum but the cases will bulge just slightly.
Accuracy has been as good with 9mm and .38 Super as it was with .38 and .357.
Ruger has also just announced a 9mm Super GP-100..
Ruger(R) Super GP100(R) * Double-Action Revolver Models
Bob