Unfortunately only trail and error will show what regiment is required with your Ml and combo. I don't use pellets but I know many who do andregiments vary(some swab, some don't). I have found that pyrodex is more forgiving in this nature as 777 has some fouling issues that may prevent (ie: crud ring) follow up loading.

I know personally with loose 777 for groups I require swabbing between shots. My regiment is a moisten patch with 50% alky and 50% blue washer fluid, run down the bore in short strokes, flipped and repeated. Then follow up with a dry patch down, flipped and down once more. If i don't hear air escaping the nipple while pushing the dry patches I snap a primer before reloading. However in the field I also know that my gun will shoot/load for 2 additional shots without any swabbing if need be but always carry pre soaked patches, etc to do the above regiment as well.

FWIW if using pelletsI would stick with pyrodex, unless the 777 pellets were noticably more consistent/accurate. The positives seem to be balanced with negatives in pellet form of these two subs.

Good Luck