I cast mine a bit on the hard side. maybe a 50/50 pure lead / Linotype mix. Then add a GC when sizing to 502. I like the vale of lil gun but accuracy is lacking.
I just got home form the range myself.
I shot about 7 different loads for the 500. Most (4) where same as usual. I start with a half way decent group, then an unexplainable flyer....... Until I tried some H4227 powder with a 3000FTX bullet. These shot in a line about 3" long and 3/4" wide. Better!! The next load was the same powder, with a 385Rem HP. This one shot a very nice 2" round group for all ten shots!!!!
The last load was a lite load with Trail Boss powder and my own cast 440WFNGC bullets. This shot about 18" high, so was MUCH lower velocity. Once I found my shots and got a good consistent aiming point, the remaining 6 bullets went onto a nice round 2" group. All shooting was at 50 yards. No chrono this trip.
Good luck with your loads!!!
CW