My favorite combination, one I settled on over 20 years ago, is 17 gr/2400, std primer, 215 gr hard cast SWC, firm roll crimp, brass trimmed to same length. Substitute a 210 gr jacketed bullet, add .5 gr, the rest is the same.
These are tremendous loads in all three of my M57-2s. I tried slightly more powder, found I got more pressure than I liked in these guns.
2400 is an agreeable powder to get along with. It lights easier, by far, than ball powders, hence the standard primers. It has always been superb for accuracy.
As others above have noted, mid-range mild charges of Unique produce very accurate loads as well, but as I've gotten older I much prefer one load and learn it well (I count the jacketed and cast bullets as one load, as they print to the same POI at 50 yards). If I want a gun to shoot bullseyes and nothing else, pretty hard to beat a .45 match gun, or a Model 41 .22. These .41 Magnum guns are built for power, however, and that's how I load them.