Ok I have been punching some numbers here. JBM - Calculations - Trajectory and I'm struggling to work out why I should use anything heavier than a 150 grainer. I'm not a physicist but I'll try anything once. Due the fact that as the bullet gets heavier the speed gets lower I end up with less energy. Since the barnes TSX retains most if not all of its weight as it passes through the target animal. Doesn't this mean all the energy will be transfered to the target until the bullet eventually stops. I understand that I heavier bullet penitrate more but concidering that the surface area of the bullet is .3". The only resistance is the frontal area of the bullet. To calculate how far anything will travel I would have thought the formula would be something like energy minus resistance irrelivant of weight. Anyway. 130 grain, muzzle vel 3700 ft/sec = 1000 meters vel 1205 ft/sec = 419 ft/lbs 150 grain, muzzle vel 3450 ft/sec = 1000 meters vel 1395 ft/sec = 648 ft/lbs 168 grain, muzzle vel 3350 ft/sec = 1000 meters vel 1249 ft/sec = 582 ft/lbs 200 grain, muzzle vel 2950 ft/sec = 1000 meters vel 1136 ft/sec = 573 ft/lbs And as far as I can tell it's all down hill from there. The 150 grainer also has the shortest flight time. I have had a little experience with formulas for vehicle accidents and skid distances calculating speed. The formulas used for this don't consider the weight of the vehicle but the friction increases in line with weight due to gravity but this obviously isn't a consideration in bullet penitration. Anyway thoughts please.