I've only shot two pounds of Black Horn 209 off, so I am no expert with it. I did find that a good hot primer is important. Also a tight fitting sabot seems important. As for why it will not group with the 240 grains XTP's? Perhaps try some 250 grain Shockwaves. The additional 10 grains should not make a large recoil difference, and it might be more accurate. All you can do is try at this point.