ItalianSxS, I think the statement you heard was misconstrued a bit. As a generalization,(which means it generally isn't accurate enough to be reliable)the highest pressures occur WITHIN the first 10 -14 inches - meaning after that first 10 -14 inches the pressures have diminished to much lower levels as 2-Piper said above. If the trend to create slower burning powders like Longshot continues, that 10 -14 inch generalization will increase. This type powder generates lower peak pressures but gains velocity by sustaining higher pressure than other powders further down the barrel. If you look at Rabbit's pressure curves above, the area under the curve represents work performed in moving the shot down bore. An optimum powder would raise pressure to some reasonably high pressure without a peak and sustain that pressure pretty much throughout the length of the bore. The area under the curve would increase quite a bit as would velocity. Of course all our guns would then be obsolete and the new ones would have much thicker barrels further forward (or metalurgy would have to improve immeasurably.)
