76chevy - 150 Yds is about all I can get out of my TC also, and I've played around with a bunch of different kinds of bullets and loads.

I've got a slug gun that is about as good as you can get; Savage bolt action 12ga, fully rifled, sporting a Leupold 3x9 scope and shooting Federal saboted Barnes copper loads. Zeroed at 100 yards, it drops 6" at 150 yards and 18" at 200 yards. Have worked with it extensively.