Mike, I think they follow that line over some safty issues. My chrony and the trajectory at 250 yds says other wise. Also if they were true why would it shoot a lot tighter groups with 140 grins of BH. I believe that 110 to 120 is the max efficient load with most powders not trure with blackhorn, the pressure readings bear that out to.
The point od diminising returns is between 90 and 100grains the point where the velocity starts backing up is over 135.