Wabi might have the reason for your situation. And that is, many of the old T/C Rifles were set up to shoot roundball or maxiball with what we now consider moderate powder charges. You remember when they came out.. a heavy load was 100 grains. And NO ONE shot that much powder it seemed. We killed our deer shooting 60-80 grains of powder and never knew you had to push the bullet any harder. Also other then the military rifles that shot 60 grains of powder, 99% of us shot roundball it seemed.

I remember when Knight came out with their MK85 and I was reading a magazine article about the rifle. And Tony Knight also talked about shooting 100 grains of powder and a pistol bullet in a plastic sleeve. My muzzleloading shooting buddy and I howled laughing about someone doing something so silly. I guess we laughed too soon.

It might be the recoil causing the rise. But even that, the amount seems rather extreme. Also the manner or sight picture you use can make a difference. But again, no two rifles are the same. But I am glad to hear you have it all figured out. My buddy used to remove the front sight off his rifles and solder half a silver dime as the front sight on all his rifles. Then he could trim that dime and he claimed that silver made them stick out like a sore thumb.