I don't remember the exact velocity loss with the .17 Remington but am pretty sure it went from about 4,000 fps to around 3,600 fps. So the energy loss would have been from 892 ft-lbs to 723 ft-lbs. The energy the bullet attains should be the energy calculated from the area under the pressure curve minus losses for friction and the energy the gases attain in achieving their barrel exit velocity. Anyway, assuming the same pressure curve, the bullet achieves 169 ft-lbs less energy. It would seem that that loss would be atrubutable to friction from the rough throat. And in addition the pressure curve may have more area under it after the throat got rough. I assume this given that it appears the pressure with the rough thoat because the primers cratered after the throat got rough versus primers which did not crater when the barrel was new. So there was probably much more than another 169 ft-lbs of energy lost to friction given more area under the pressure curve unless somehow the pressure dropped more on down the barrel compared to when the barrel was new. This makes me wonder how long it took my .17 Remington to basically start giving .17 Hornet performance?