I don't think you can blame the crud ring on any one component . When 777 first came out I was one of the first in my area to shooting it, in fact no one on the muzzleloader league I was on used it but me. I used a 45 caliber GM barrel with 1:18 twist that was fitted to an old H&R break open shotgun and used 209 shotgun primers. I shot hundreds of rounds thru that gun that summer and would probably shoot 20 bullets at a time without wiping and never experienced a crud ring or even heard of it at that time. By Fall I picked up a 45 caliber Omega and that's when I discovered the crud ring but couldn't figure out why.
Looking back now , when I was using my league gun I only used 50gns of 777 with plain old Winchester 209 primers and shot mostly Lyman Whitworth bullets. You might think that because the Whitworth has 7 grease grooves that probably kept fouling down so no crud ring but I actually shot a lot of 200gn pistol bullets with the 50gns and still no crud ring. Any time someone asked me about 777 ,I just couldn't say enough good about it.
When I got the Omega I started shooting the Lyman 457193 and the Gould bullet because they were both shorter and on paper looked to be more suited for the 1:28 twist but I just wasn't getting good accuracy even with different 209 primers so I kept upping the charge until I was at 100gns with livable shot groups but the crud ring was very evident. I shot a lot of deer with load but it kicked like a mule.
My thinking now is that the Omega wasn't giving me accuracy with low charges was probably caused by the QLA and nothing to do with 777, primers or the bullet I was using but since I no longer have it I can't prove otherwise. I'm also thinking that the crud ring wouldn't been an issue had I been able to use low to moderate powder charges.