Never had the "crud ring" problem with my Knight USAK with #11 caps. At worst, my only problem was a sticky breech plug which was cured by the teflon breech plug tape.
777 will be my 1st & 2nd choice in powder unless something newer and BETTER comes along. BM3 is worse in my 22" barrel and while CleanShot (APP) shot well in it, I did have moisture issues with it, while 777 has been 100% reliable since I opened my 1st bottle of it.