Sir, a few reasons, mainly having to do with too many variables.

Bullets of a given weight in a given caliber can still have very different shapes, as well as different crimp groove locations, which affects seating depth and working case volume.

Jacketed bullets also have a higher coefficient of friction than lead, which means they're harder to push down the bore, and which raises pressures, all else being equal.

And if you're talking about loads that have to fit in a box magazine, that also affects permissible overall length.

There's just too many different variables to make a useful universal graph.

Hope this helps, and Semper Fi.

Ron H.

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