.45 Colt mostly because it does the same thing as a .44 Magnum at less pressure, about 10kpsi less when both are loaded to the max.
One of the gun world's oft repeated old wives' tales. Newton's 3rd Law also has an issue with it.
Perhaps you don't understand Newton's third law. The 45 has 10% more area over which that pressure is acting, and hence at the same pressure as the 44, the 45 is going to have a greater reaction. Conversely, the 45 requires less pressure than the 44 to achieve the same velocity, a proper application of physics not some old wives tale.
You almost had it. Stick to the part about the .45's greater area multiplied by the lower PSI equaling the total pressure of the .44 Mag. Compare the bolt thrust and hoop stress between the two cartridges.
PSI alone is a single variable and only tells part of the story.
Forgive me my nonsense, as I also forgive the nonsense of those that think they talk sense. Robert Frost
