Up until a year ago I was shooting with ACC arrows and was consistently shooting tight groups out to 50 meters. After that the group opened up a bit. On advice, I upgraded to the Nano XR, but ever since I have struggled with shooting tight groups on a consistent basis. I find them extraordinarily sensitive to a smooth release, with even the slightest variance resulting in large changes down range – even at 30, 40, and 50 meters. Any thoughts? The arrows have 120 grain points, spin wings, and have been tuned to the bow. Would a heavier arrow be better? I'm hunting for answers here. Thanks!!