I wish I felt comfortable paraphrasing what MD was kind enough to explain to me with respect to pressure & velocity, but it's counterintuitive and I don't want to screw it up.
Well... in general (and John, feel free to b!tch-slap me if I screw this up): the effects of things like a rougher bore or looser chamber in our factory rifles, compared to the near-perfect pressure barrels the ballisticians use, are actually negligible. Therefore, pressure = velocity; a given pressure will make a given velocity, and the effects of the above won't matter much.
More non-intuitive yet, velocity = pressure. Therefore in most cases, pressure can be directly derived from an accurate chrono reading.
Finally some of the classic pressure signs are actually not. Such as sticky bolt lift; that can simply be lugs that are out of square and binding. So- say you are at max powder charge (says the book) and are experiencing sticky lift, but are 150 fps below the speed the book says with equal barrel length. Absent "real" pressure signs, like head expansion, you can add more powder until you hit that book speed, at which point your pressure will be very similar to the book pressure.
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This is basically a refutation of the notion of "fast" and "slow" bores by the way.
Please take the above as MY retard-version of what MD might be saying. Do not attribute my words to him; any serious questions should be directed his way as I am still trying to wrap a brain around the implications of what I think he was telling me.
