I haven't had time to try a lot in my Beartooth Magnum but it shoots 240 & 260 gr Deadcenters with 90 gr of BlackMag3 pretty well. I tried 777 pellets with a variety of bullets & primers, the 'crud ring' was horrible. With Blackmag3 I can keep loading & shooting without any swabbing and at the end of the day one patch and it comes out clean. I haven't tried pyrodex yet but my friend shoots 100 gr of pyrodex pellets and a 223 gr Powerbelt out of his with good results.
Joe