If your basic rules of internal ballistics say that the "capabilty" of the 8x57 yields 200 fps more velocity, so be it. My old chrono did not measure capability.
They are not exactly "my" rules, though I did come up with the basic formula after analyzing published, pressure-tested data. Instead they're a basic reflection of internal-ballistic physics, analyzed by crunching the numbers published in dozens of sources of pressure-tested handloading data.
That said, one of the nifty things about handloading is we can put together cartridges that result in whatever velocity we want. And chronographs are useful in that quest, as part of the big picture--if you know how to use them in that role. Which I have also explained (and demonstrated) in a lot of my published writing.
If bullet/bore diameter didn't matter in rifle cartridges of the same size, then the .243 Winchester would be capable of getting the same velocities as the 7mm-08 with the same bullet weights, when loaded to the same pressure. It isn't--and the difference in bore area (not diameter) between the .243 and 7mm-08 is similar to the difference in bore area between the 7x57 and 8x57.
