i know teachers are always right ... this is why i am asking how far do you think a muzzleloader can shoot... he says his neighbor shoots 600 yds

Much farther.

1000 yard matches are still held. http://www.lrml.org/news/2006/0610_OakRidge.pdf

http://www.lrml.org/news/2006/butnerusimlt2006.htm

http://www.lrml.org/technical/technique/backposition.htm I would be screaming in pain.

Realistically, a normal shooter can rarely shoot over 200 yards. I guess some people have the ability for that long distance stuff but not me. I limit my shots to 100 yards with open sights.

Depends on high a "normal shooter" raises his barrel. Don't ever think there is some brick wall that stops muzzleloader rounds at short range - they can and do travel somesubstantial distances.