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45-70 Government (350 Speer SP)            308 Winchester (150 Speer GS)
Propellant   Predict Actual Differ             Propellant Predict Actual   Differ
IMR-4198 2012   1814     -198                 IMR-3031 2733    2725        –8
Re-7          2147     1934   -213                 IMR-4895   2614    2673      +59
IMR-3031 2025   1786     -239                IMR-4064 2862    2727    –135
H322           2130    1927 -203                 AA2520      2641     2748    +107
N133           2087   1995    -92                 W748         2743    2713    –30
IMR-4064   1961   1761 -200                 N140          2658    2744       +86
IMR-4320 1947     1758    -189                 Re-15        2767    2812       +45
H4895      2151    1997     -154              IMR4350   2590    2572      –18
H335          2213    1955    -258                H414        2667    2699      +32
Average Predictive Error -194                Average Predictive Error      +15

Hence, I contend that in long cylindrical cartridges QuickLOAD predicts more pressure and velocity than are actually produced specifically because such calculations are based upon the assumption that primer plume and secondary ignition ignites essentially 100% of granules before significant bullet movement occurs; hence, because this assumption is erroneous, QuickLOAD dramatically overestimates pressure and velocity. Conversely, in the bottlenecked cartridges, the shoulder does two things; first, it delays plug movement so that additional pressure builds before the unignited propellant begins to push the bullet down the bore; second, it disrupts the plug so that much of the initially unignited material ignites before the bullet can move far into the bore.