Limbsaver makes buttpads for most of common muzzleloaders. That will help the recoil.
You may find a difference in trajectory in shooting a muzzleloader at 800 vs. a 30/30. I would look at shooting at a more ethical range of 200 yards and enjoy the hunt.
ddj
Many men go fishing all their lives without knowing that it is not fish they are after. - Henry David Thoreau
The best part of hunting and fishing was the thinking about going and the talking about it after you got back. - Robert Ruark
