I finally got to take my Model 57 out to the range today. I had some old handloads lying around, these were some of my very first done on an old Lee balance scale. 220 grain SWC's and 8.5 grains of Unique. All in all not bad for a shooter, I need to have the ejector rod straightened has a slight tweak in it, but otherwise in good shape. There is no flame cutting at all in the topstrap so it wasn't shot alot.
That 4" configuration is a fine one for a .41 Mag. Best of luck with it. My favorite lower-mid power load when I hand loaded was 7.4gr 231 and a ~215gr cast Keith-type. [Unfortunately that bullet supplier out of business]