I'm trying to understand som basic rifle bullet physics regarding pressure inside the gun barrel. For no particular reason I'm comparing the .308 and 30-06 cartridge. When reading specs on the two I get confused. They both have maximum pressure levels around 415 MPa, but how can that be when the 30-06 case is more than a centimeter longer than the 308? If they are both filled with propelant, won't the 30-06 produce higher pressure just from having a longer case? And if they both produce the same pressure - does that mean that bullets with identical mass go the same speed and have the same energy?