Do you have reliable access to longer distances? I've never even fired mine at under 300. Like someone mentioned it seems the bigger bullets take some distance to settle in. I've actually never shot mine for groups but I have gone 10 for 10 on an 8.5" steel gong at 700 yards more than once and average 8 for 10 on a 20 inch gong at 1500 yards using around 101 grains of US869 (I forget the exact number and don't have my notebook with me).

I'd suggest before you write it off take it someplace and let it stretch it's legs. I know it's common belief is that groups don't get better as distance increases, but if the bullets are still in nutation, they won't print like you'd expect.