I was sighting in my 14 yo daughter's CZ 572 (for the second time - she did it once, but I wanted to be sure). I was using cheap 55-grain 'American Eagle' FMJ and the shots were OK, but not really as precise as I like. Since this is for a deer, once I was close, I started sighting in with the actual hunting ammunition - 64 grain Winchester 'Super-X Powerpoint'. The groups literally shrank to a third the size of the 55-grain groups. This was kind of eye-opening. I had just had assumed the 55-grain ammo would group just as well; in fact the 'PowerPoint' tip is exposed lead, and not as regular as the FMJ, so I thought it might not spin as evenly. In the event, that was definitely NOT the case. Anyway, lesson learned.