Pressure/velocity/distance diagram
The pressure/velocity/distance diagram also illustrates quite neatly that, with a 25" barrel, the Swiss cartridge is going to produce approximately the same muzzle velocity as the 308 cartridge with 20" barrel.
The work done on the bullet is the integral of (force x distance), i.e. proportional to the area under the pressure curve. The area under the pressure curve section from 20" to 25" for the Swiss cartridge is roughly the same as the difference between the 308 and the Swiss curves at the start of the curves. But the peak pressure is considerably lower, for the same amount of energy imparted to the bullet.
Which is the simple reason why those old, long rifles can achieve a trajectory that is nearly as flat as more modern "carbine" length rifles, but with a slower powder, lower peak pressure, and a generally more "shoulder-friendly" behavior. Something which I favor more and more with every year! (My Swiss is one of the last G96/11s)
Patrick
:wave: