777 doesn't leave a crud ring in all muzzleloaders in all situations. It happens always in my TC Omega and Encore, but never in my TC Hawkens or Renegades. The crud ring is almost non-existant in my Knight USAK. It also appears to be somewhat dependant on primer selection in some muzzleloaders. Many people have have gotten rid of or reduced the crud ring by using different primers (like the new Winchester triple Seven) or the VariFlame Primer Adapters.
Search the board for past discussion of the infamous crud ring for more information.
I have been using APP with great success in my .50 cal sidelocks with roundball or lighter sabot and conicals (250 gr or less), but I can't hit the side of a barn with it in my .58 cal with heavy conicals (525 grain). 777 is great for that. Go figure.
As 12 Ring said, that's what makes it so much fun.
As always, your mileage may vary,
tooldog