I didn't plan on doing any work on this, but then my fountain pen pal decided to go all technical on the topic. It will take a bit of time to provide my data answer due to work obligations, but I've already started and will provide a preview of the "ground rules" I mentioned earlier in the thread:
- @Alistair the difficulty with your data is you have no dependent variable; this is why your calculated efficiency is increasing with increasing bullet weight, which invalidates the output. You are holding the powder type constant, but it is not a variable in the equation. The variables are: bullet weight, powder charge, and velocity. One of these has to be held constant. Given the tabulated data we have to work with, the only one that can be held constant is the bullet weight.
- A secondary difficulty is the Hornady load book which gives rough velocity ranges with no indication of pressure. The best thing it provides is technical data of it's own bullets. I have found that the powder companies, especially Hodgdon, provides the best comparative data.
- Varget is a good powder type to span the entire caliber range without restricting bullet weight, but we have to select powder types that are typical of the largest range of hunting cartridges of interest.
- This means we have to constrain the cartridge selection such that the powder type AND bullet weight spans a cartridge range of interest.
- Example preview #1: Using Hodgdon load data, select 300gr bullet as the dependent variable and compare cartridges using constant powder types H4350 and H4831 which gives a four-caliber cartridge range of 338 Win Mag to 416 Rigby. Calculate the energy and divide by the powder charge to get a relative efficiency calculation sorted in descending order.
- Example preview #2: Repeat Ep#1 with 150gr bullet as the dependent variable with the same constant powder types which gives a cartridge range of 6.5CM to 8mm Rem Mag. Mix these in with the 300gr bullet results to get an overall efficiency ranking.
- Repeat this process with several other bullet weights of hunting interest and compile two lists: one list dependent on powder type; the other list independent of powder type.
- What you find from the preliminary results are the following (preview):
- At equal bullet weight, smaller calibers tend to be more energy efficient than larger calibers (nearly the opposite of @Alistair conclusion, which says that if bullet energy is the most important thing, choose the smallest caliber that provides the bullet weight and energy needed for the task.
- The following example will illustrate this point: In my tabulated calculations SO FAR from 150gr 6.5CM to 300gr 416 Rigby, a 300gr 33 Nosler is the most energy efficient cartridge with H4350 and the third most efficient with H4831. But change the bullet weight to 180gr and it becomes equally efficient to the 300 Weatherby and... the 30-40 Krag! BUT at almost double the energy of the Krag! This is why efficiency across caliber classes is near to completely meaningless.
That's all the preview commentary for now. I've completed a large chunk of cartridge calculations and will share when I can get to it, along with more detailed ground rules. Goodnight all!
PS Edit: My parting shot is that there are other variables that are changing that aren't in the equation... (1) case design + case volume + caliber is what we are comparing; (2) bullet design/MOC, seating depth/OAL, and barrel length we have to account for OR assume we can ignore differences in these. This is where the powder data is better than the bullet data in most cases. Finally, because we are using static tabulated data, we have to assume we can compare maximum charge and velocity shown is at maximum safe pressure at all times (or at least that the maximum charge and velocity can be compared across all loadings). Again, it's an academic exercise for fun, but I think it will verify things people already know logically or from experience (or apathy haha).
