I also shoot a stainless bighorn. Off hand it depends on how shaky I am that day, always within 3-4 in group at 100 yds, 4in I would not be happy with. At the bench last week I shot through the same bullseye hole at 50 yds everytime, shot a 2 in group at 100yds and a 3 in group at 150yds. Those barnes bullets made a world of difference for me. I personally don't care for pellets. They will misfire much easier in damp weather, and just don't have the punch that loose 777 powder does. In my experience 150 grains is too much and causes in accuracy. I have tried different powder charges and 110 shoots best for me. But every bore is different as is every shooter.