Oh really? Well half the bolded statement is fact taken from Hodgdon.
Look at the data you posted in its entirety, not just what you think supports your opinion. Unique and Titegroup usually yield similar velocities at similar pressures. Unique pushes the 300gr to near 1300fps at only 38,600CUP. Even Bullseye gets the damned thing over 1000fps with only 33,000CUP.
FA260JFP UNIQUE 12.0 1220 33,600 15.0 1452 46,600
FA300JFP UNIQUE 10.0 1049 30,600 14.0 1275 38,600
Here's another from Lyman (43,000cup). That's a significantly heavier bullet nearing 1200fps at only 43,000CUP.
325 Cast #452651 Alliant Unique 12.6 1181
Even Hodgdon's .45Colt data gets a 300gr to over 1000fps at 28,500CUP. You don't think one can gain another 200-300fps with double the pressure?
Hodgdon Titegroup .451" 1.650" 7.5 851 20,400 CUP 9.0 1,004 28,500 CUP
Speer's
reduced .454 loads get the 270gr RCBS/SAA bullet over 1100fps.
270 Speer SAA Hodgdon Titegroup 9.0 1135
So there's a good reason why I posted what I did. I didn't pull that from my posterior orifice and no, I didn't just fall off the turnip truck.