Hevi shot jams my mossberg 930

[drywallerdave]

After about 5 shots my barrel gets so dirty with residue that my shotgun begins to jam.  I then have to clean my gun down to cleaning the piston out because it will be full of gunk. I love these rounds but I am going to switch to Winchester long beards this year. Hopefully they will be a cleaner round...anybody else have problems like this with hevi shot?

[penna shooter]