If you had an arbitrary set of specifications, such as "One inch expansion and a total of 13" Penetration through calibrated ballistics gel" Is there a formula to calculate the ratios of diameters, masses, weights, and velocities that would work to achieve that performance, assuming the metallurgy knowledge was there to tune the HP to expand predictably and consistently? Obviously the more the round expands the more it experiences drag (like a parachute) and the more quickly it loses velocity in tissue which can lead to less penetration... increasing overall velocity may compensate somewhat assuming the bullet doesn't over expand or tear itself apart, so maybe increased mass (and therefore momentum / inertia) would be superior in achieving the depth of penetration with that kind of expansion. The bullet would have to be designed and tuned to those tolerances and particular velocity ranges. Basically if you were to come up with a novel cartridge design from a clean sheet (not just a wildcat unless that would meet your criteria) just as a thought exercise, how would one go about calculating it so that it's in the ballpark? Wanna kill these ads? We can help!