I had used Nosler ballistic tip bullets for many years, and now love the terminal performance of the accubonds. I especially like that my rifles shoot the same with both bullets so I can practice & coyote hunt with the cheaper BT bullets and load the AB's when heading out for bigger game. I have always noticed that the ballistics programs show that my trajectory should be flatter than it actually is. I chronograph all my loads so the BC should be the only variable. I purchased "Applied ballistics for Long Range Shooting" the book last winter, and found that their BC tests had the 7mm bullets nearly .05 lower than Noslers posted BC. Other calibers varied in their results but all were lower than Nosler's version. Anyone else seen this or have a system for finding a more accurate BC to predict trajectory/wind drift with?