I was out shooting today with my Model 57. Loaded with 15.5 grains of IMR-4227 under 215 grain lead SWC and CCI-350 magnum primers. It was 50 degrees and velocity from my 4" barrel was 900 fps on the money. Very accurate and plenty of power for my needs. The same load runs 970 fps from my 4 5/8inch Ruger Blackhawk. I wouldn't reduce this load any more because it's such a slow powder. 16.0 grains even would be good to try.

I also have used 6.7 grains of WW-231 and Winchester std. large pistol primers. It runs 950 fps from my Ruger, I haven't shot it over the chronograph using the S&W yet.

These loads are by far my favorites. I've tried all sorts of bullets and powders and always come back to these. Very controllable, but not anemic in the least. I consider them great self defense loads.