Well Larry, the point is "IF" the same ballistics are met, if the max pressure is lowered it "Will" be made up somewhere else. The laws of physics have not been changed. As max pressure is reached inside the chamber the "Make-Up" occurs over the rest of the barrel's length, so the difference in pressure is much slighter than is the Max.
Bottom line is though that shooting a "Low Pressure" (IE low max chamber pressure) load ii no way makes t Easier on the barrel at a point some 18" down the bore. The pressure there will in fact be very sightly higher, though mostly insignificant. Just don't be fooled into thinking that shooting low pressure loads are of benefit anywhere other than in the chamber itself for they are not.
With all due respect to Drew, the problem is the pics he posted are simply not detailed enough to show that slight cross over. It is simply impossible to get the same ballistics & have that much difference in max pressure & it not be compensated for else where.
What you say is true, Miller. But we know for a fact that we can have loads that differ by a few thousand psi PEAK pressure. It'd be interesting to chart loads with those very significant differences vs those that only differ by 1,000 psi or so peak pressure. But what the old Dupont charts show--like Drew's, and like the 1933 chart I'm looking at--is that by the time you reach 6" from the breech, the difference is already insignificant--in the range of 500 psi.
So it seems to me that it depends on where you're worried about pressure, because from 6" or so on, the curves merge together even closer. As far as pressure is concerned, beyond that point there's no reason to concern yourself at all--at least as far as the difference between loads is concerned. If your barrel is going to fail due to pressure at that traditional 9" measuring point, I doubt that the lowest pressure load at about 3,600 psi would save it from happening with the highest pressure one at 4,000.
