Of course a quartering shot will give the most mass to penetrate and limit the chance of pass-throughs, but try one of the Barnes options. Since you are close range, the 110 gr TSX should open quickly but retain ~100% of its weight. The Accubond that you have already been using is about the strongest construction of any of the 6.8 bullets that will still allow good expansion. More choices are surely to come, but it is hard to beat a monolithic like Barnes for expansion and weight retention. If you reload, the 95 TTSX may be even better.