I used to shoot a CVA Buck horn, the best load I found for that rifle was 95 gr. 2F Goex Black powder with 223 gr. Power Belt Areo Tip Bullet. With that load benched off a Cauldwell Lead Sled @ 85 yards would dang near put them in the same hole. My I suggest starting off at 75 grains and working up 5 grain at a time. The key to a good group is having a solid foundation : bags of sand, shot, lead sled, scope adjustment (were you can find that sweet spot every time on the back of stock) what I mean is closing your eyes get in to firing position and then open your eyes and having "FULL" view in your scope. I see more folks creeping up or backing off on the stock to find that sweet spot. Basicly it equals to slipping into position on that stock and gun right everytime. This will make our ability on that gun go upwards. I sold that CVA to a buddy for his son. All my Whites like diiferent loads, all will shoot less than 1 1/4" group @ 85 yards all shoot different loads & weight in slugs. All have that magic sweet spot on that stock when I shoulder it it's there everytime on the 1st time I shoulder that gun.
Sometimes less powder is best. Good Luck