I'v chronographed some loads using a cast Hensley & Gibbs #51 160-grain SWC in a 2" barrel. My notes don't indicate whether these were fired in a Detective Special or a Chief, but I'm pretty sure it was a Chief.

3 Bullseye - 648
3.3 Bullseye - 683
3.5 Bullseye - 730 good accuracy
3.5 Titegroup - 702
4.3 231 - 729 good accuracy

Same loads also chronographed in a 6" K-38. Velocities are approximately 100 - 125 fps greater than in a 2" gun.