We all know that reloading manuals are to be used as a guide only. Each gun is different, and the variables are endless. Most reloaders are primarily concerned with muzzle velocity and are only concerned about pressure when indications start to show up on the primers or the case itself. Because we can’t measure barrel pressure, my question is this: As long as the powder type, bullet, and muzzle velocity is the same as what’s published, is it reasonable to think that the barrel pressure will correspond to the published value, regardless of what our powder charge weight is? For example, say I’m loading for my 30-06. The IMR manual says that with 165 grain Sierra SPBT and charge of 51.2 grains of IMR 4320, they get 2869 feet/sec, which will result in 58,600 psi. Now lets say, if for me to get 2869 ft/sec in my gun, I must use 53 grains with IMR 4320 and the same bullet, will the barrel pressure still be about 58,600 psi ? Also, if so, now because we are talking about muzzle velocity, would a different bullet of the same weight, say a Hornady 165 grain SST at the same velocity (2869 ft/sec) and using the same type powder (IMR 4320), produce about the same pressure (58,600 psi) ?