Hevi-13 shells

[mossyoak]

First off Hi to everyone as I am new to the board. Second I have been shooting federal flight control wad #6 for two years now and I keep hearing how hevi-shot are so much better. Well I bought a box of 5 3 1/2 #6 and they shoot about 6 inch higher than my old ones. Does anyone else have this problem? Also I was using a xtra full choke in a win sx2. Any info is appreciated. Thanks