ORIGINAL: outdoorslover
I would honestly blame it on your shooting above everything else. I could probably only get like 6 inch groups at 150 yards. Are you shooting with open sights??? It could be a hundred different things but I would say it's the shooter.
I've got no reason to believe its the shooter. I am reminded of a 164 yard target recently posted here. The guy seemed apologetic about his wide but very narrow in elevation 5 or 6 shot grouping. It was immediately clear to me, though, that he was a remarkable marksman. Less than .75 MOA in elevation which describes accurately his aiming precision which was sharpshooter quality. He described the range conditions as windy and as little as 4 mph fluctuation would have accounted for all of the windage distribution of the grouping.
It was also clear to me that his sights were WAY off. And he did say that he adjusted his sight's windage to keep the shot on the bull. Wind is very important in muzzleloading at the extreme ranges.