Well I had very poor luck with 777 also. Be aware a tight sabot one that takes both hands to push down gives the best results with Blackhorn. also that There are good and poor places and ways to buy it. I buy mine at powder valley for 24 dollars a can + Hazmat which is not to bad as I buy by the case the only exception has been when I caught it on sale and got it cheaper.
My Endeavor Encore and my Triumph both shoot considerably more accurate wit it than with 777.