There are probably some minor differences in these guns. I've only had one 52-2 so am not real knowledgeable. However, I had little trouble in finding a load that fed perfectly and was very accurate. Overall cartridge length using an H&G #50 with a minimal roll crimp was 1.16", but I suspect that acceptable OALs might vary slightly from one gun to the next.
I used .356", .357", and .358" sizing dies and those sized in the .358" die were the most accurate, though actual sized bullet diameter was .3575". Here again, best diameter may vary in some guns. 2.5 grs. Bullseye at app. 750 fps outshot heavier charges, but again, I wouldn't expect this to be the best charge in all guns.