hey
Now i'm not a long time muzzleloader and don't pretend to have all the answers but go back and read your own post. You have a brand new gun, with a brand new scope, 3 or 4 different bullets, all of different weights, shot at two different distances, by two shooters and none of the bullets were shot more than three times. The 300 grain deadcenter shot well at 50 yards( two touching and one 1inch away)and at 100 yards two touching and one 3 inches away. Sounds pretty good to me. I'd keep shooting the 300 grain dead center and see if it was the gun or maybe the shooter. ( we all can't shoot perfect groups at 100 yds all the time.)
If i could shoot my first six shots, from my brand new gun, as good as you did with the 300 grain dead centers, i'd be a happy shooter.
My two cents worth of advise would be, go to the range with 100 rounds of 300 grain dead centers and shoot them all, spit patch after every shot, stay with the same powder that you were using and shoot between 100 and 120 grains. Try to get those groups tighter by makeing little changes, not big ones and i almost forgot, leave your buddy at home!!!
little red