Quote:
Originally Posted by Salavee
Physics .. equal pressure and equal resistance results in equal velocity ..Various charge weights, various burn rates, various load densities equals various pressures, which equals various velocities. Have you actually tried loading different powders in the same case, for the same firearm with the same resistance and realized equal pressures /velocities ?
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Have you actually looked in a loading manual where they list the actual peak pressure of each load? Why do you suppose two loads can produce the same peak pressure, and yet produce different velocities with the same bullet? This happens because although the peak pressure is the same, the pressure curve is different. One powder produces pressures closer to peak pressure for a longer duration, which results in more total energy being used to accelerate the bullet.
Here is a chart from my Hodgdon manual which shows the actual pressures of some loads, notice that some powders produce more velocity with less peak pressure. H4831 actually produces 338fps more than h322, while producing 1800cup less. That is a difference of around 14% velocity wise, while producing over 3% less pressure. If you doubt the numbers, take it up with Hodgdon, they produce the powders, as well as the manual, so they should know what they are talking about. I used 30-06 data, because they didn't list the pressures for the 6.5x55.
