If the conical is flat bottom, the rule is put a wad. Although it does not hurt to try them both ways. For instance, I shoot 70 gr of T-7 3f all the time in the White with a conical and no wad.
My hunting load last season was a 410 gr. great plains hollow based conical and 90 gr. of 2f 777. It turned out to be a very accurate and consistant load. Off sand bags, groups averaged 1.75" with several groups running 1.5" at 100 yards out of my inline. It did quite a number on a doe and a hog last season.